operator in assignment statement

Python Enhancement Proposals

• Python »
• PEP Index »

PEP 572 – Assignment Expressions

The importance of real code, exceptional cases, scope of the target, relative precedence of :=, change to evaluation order, differences between assignment expressions and assignment statements, specification changes during implementation, _pydecimal.py, datetime.py, sysconfig.py, simplifying list comprehensions, capturing condition values, changing the scope rules for comprehensions, alternative spellings, special-casing conditional statements, special-casing comprehensions, lowering operator precedence, allowing commas to the right, always requiring parentheses, why not just turn existing assignment into an expression, with assignment expressions, why bother with assignment statements, why not use a sublocal scope and prevent namespace pollution, style guide recommendations, acknowledgements, a numeric example, appendix b: rough code translations for comprehensions, appendix c: no changes to scope semantics.

This is a proposal for creating a way to assign to variables within an expression using the notation NAME := expr .

As part of this change, there is also an update to dictionary comprehension evaluation order to ensure key expressions are executed before value expressions (allowing the key to be bound to a name and then re-used as part of calculating the corresponding value).

During discussion of this PEP, the operator became informally known as “the walrus operator”. The construct’s formal name is “Assignment Expressions” (as per the PEP title), but they may also be referred to as “Named Expressions” (e.g. the CPython reference implementation uses that name internally).

Naming the result of an expression is an important part of programming, allowing a descriptive name to be used in place of a longer expression, and permitting reuse. Currently, this feature is available only in statement form, making it unavailable in list comprehensions and other expression contexts.

Additionally, naming sub-parts of a large expression can assist an interactive debugger, providing useful display hooks and partial results. Without a way to capture sub-expressions inline, this would require refactoring of the original code; with assignment expressions, this merely requires the insertion of a few name := markers. Removing the need to refactor reduces the likelihood that the code be inadvertently changed as part of debugging (a common cause of Heisenbugs), and is easier to dictate to another programmer.

During the development of this PEP many people (supporters and critics both) have had a tendency to focus on toy examples on the one hand, and on overly complex examples on the other.

The danger of toy examples is twofold: they are often too abstract to make anyone go “ooh, that’s compelling”, and they are easily refuted with “I would never write it that way anyway”.

The danger of overly complex examples is that they provide a convenient strawman for critics of the proposal to shoot down (“that’s obfuscated”).

Yet there is some use for both extremely simple and extremely complex examples: they are helpful to clarify the intended semantics. Therefore, there will be some of each below.

However, in order to be compelling , examples should be rooted in real code, i.e. code that was written without any thought of this PEP, as part of a useful application, however large or small. Tim Peters has been extremely helpful by going over his own personal code repository and picking examples of code he had written that (in his view) would have been clearer if rewritten with (sparing) use of assignment expressions. His conclusion: the current proposal would have allowed a modest but clear improvement in quite a few bits of code.

Another use of real code is to observe indirectly how much value programmers place on compactness. Guido van Rossum searched through a Dropbox code base and discovered some evidence that programmers value writing fewer lines over shorter lines.

Case in point: Guido found several examples where a programmer repeated a subexpression, slowing down the program, in order to save one line of code, e.g. instead of writing:

they would write:

Another example illustrates that programmers sometimes do more work to save an extra level of indentation:

This code tries to match pattern2 even if pattern1 has a match (in which case the match on pattern2 is never used). The more efficient rewrite would have been:

Syntax and semantics

In most contexts where arbitrary Python expressions can be used, a named expression can appear. This is of the form NAME := expr where expr is any valid Python expression other than an unparenthesized tuple, and NAME is an identifier.

The value of such a named expression is the same as the incorporated expression, with the additional side-effect that the target is assigned that value:

There are a few places where assignment expressions are not allowed, in order to avoid ambiguities or user confusion:

This rule is included to simplify the choice for the user between an assignment statement and an assignment expression – there is no syntactic position where both are valid.

Again, this rule is included to avoid two visually similar ways of saying the same thing.

This rule is included to disallow excessively confusing code, and because parsing keyword arguments is complex enough already.

This rule is included to discourage side effects in a position whose exact semantics are already confusing to many users (cf. the common style recommendation against mutable default values), and also to echo the similar prohibition in calls (the previous bullet).

The reasoning here is similar to the two previous cases; this ungrouped assortment of symbols and operators composed of : and = is hard to read correctly.

This allows lambda to always bind less tightly than := ; having a name binding at the top level inside a lambda function is unlikely to be of value, as there is no way to make use of it. In cases where the name will be used more than once, the expression is likely to need parenthesizing anyway, so this prohibition will rarely affect code.

This shows that what looks like an assignment operator in an f-string is not always an assignment operator. The f-string parser uses : to indicate formatting options. To preserve backwards compatibility, assignment operator usage inside of f-strings must be parenthesized. As noted above, this usage of the assignment operator is not recommended.

An assignment expression does not introduce a new scope. In most cases the scope in which the target will be bound is self-explanatory: it is the current scope. If this scope contains a nonlocal or global declaration for the target, the assignment expression honors that. A lambda (being an explicit, if anonymous, function definition) counts as a scope for this purpose.

There is one special case: an assignment expression occurring in a list, set or dict comprehension or in a generator expression (below collectively referred to as “comprehensions”) binds the target in the containing scope, honoring a nonlocal or global declaration for the target in that scope, if one exists. For the purpose of this rule the containing scope of a nested comprehension is the scope that contains the outermost comprehension. A lambda counts as a containing scope.

The motivation for this special case is twofold. First, it allows us to conveniently capture a “witness” for an any() expression, or a counterexample for all() , for example:

Second, it allows a compact way of updating mutable state from a comprehension, for example:

However, an assignment expression target name cannot be the same as a for -target name appearing in any comprehension containing the assignment expression. The latter names are local to the comprehension in which they appear, so it would be contradictory for a contained use of the same name to refer to the scope containing the outermost comprehension instead.

For example, [i := i+1 for i in range(5)] is invalid: the for i part establishes that i is local to the comprehension, but the i := part insists that i is not local to the comprehension. The same reason makes these examples invalid too:

While it’s technically possible to assign consistent semantics to these cases, it’s difficult to determine whether those semantics actually make sense in the absence of real use cases. Accordingly, the reference implementation [1] will ensure that such cases raise SyntaxError , rather than executing with implementation defined behaviour.

This restriction applies even if the assignment expression is never executed:

For the comprehension body (the part before the first “for” keyword) and the filter expression (the part after “if” and before any nested “for”), this restriction applies solely to target names that are also used as iteration variables in the comprehension. Lambda expressions appearing in these positions introduce a new explicit function scope, and hence may use assignment expressions with no additional restrictions.

Due to design constraints in the reference implementation (the symbol table analyser cannot easily detect when names are re-used between the leftmost comprehension iterable expression and the rest of the comprehension), named expressions are disallowed entirely as part of comprehension iterable expressions (the part after each “in”, and before any subsequent “if” or “for” keyword):

A further exception applies when an assignment expression occurs in a comprehension whose containing scope is a class scope. If the rules above were to result in the target being assigned in that class’s scope, the assignment expression is expressly invalid. This case also raises SyntaxError :

(The reason for the latter exception is the implicit function scope created for comprehensions – there is currently no runtime mechanism for a function to refer to a variable in the containing class scope, and we do not want to add such a mechanism. If this issue ever gets resolved this special case may be removed from the specification of assignment expressions. Note that the problem already exists for using a variable defined in the class scope from a comprehension.)

See Appendix B for some examples of how the rules for targets in comprehensions translate to equivalent code.

The := operator groups more tightly than a comma in all syntactic positions where it is legal, but less tightly than all other operators, including or , and , not , and conditional expressions ( A if C else B ). As follows from section “Exceptional cases” above, it is never allowed at the same level as = . In case a different grouping is desired, parentheses should be used.

The := operator may be used directly in a positional function call argument; however it is invalid directly in a keyword argument.

Some examples to clarify what’s technically valid or invalid:

Most of the “valid” examples above are not recommended, since human readers of Python source code who are quickly glancing at some code may miss the distinction. But simple cases are not objectionable:

This PEP recommends always putting spaces around := , similar to PEP 8 ’s recommendation for = when used for assignment, whereas the latter disallows spaces around = used for keyword arguments.)

In order to have precisely defined semantics, the proposal requires evaluation order to be well-defined. This is technically not a new requirement, as function calls may already have side effects. Python already has a rule that subexpressions are generally evaluated from left to right. However, assignment expressions make these side effects more visible, and we propose a single change to the current evaluation order:

• In a dict comprehension {X: Y for ...} , Y is currently evaluated before X . We propose to change this so that X is evaluated before Y . (In a dict display like {X: Y} this is already the case, and also in dict((X, Y) for ...) which should clearly be equivalent to the dict comprehension.)

Most importantly, since := is an expression, it can be used in contexts where statements are illegal, including lambda functions and comprehensions.

Conversely, assignment expressions don’t support the advanced features found in assignment statements:

• Multiple targets are not directly supported: x = y = z = 0 # Equivalent: (z := (y := (x := 0)))
• Single assignment targets other than a single NAME are not supported: # No equivalent a [ i ] = x self . rest = []
• Priority around commas is different: x = 1 , 2 # Sets x to (1, 2) ( x := 1 , 2 ) # Sets x to 1
• Iterable packing and unpacking (both regular or extended forms) are not supported: # Equivalent needs extra parentheses loc = x , y # Use (loc := (x, y)) info = name , phone , * rest # Use (info := (name, phone, *rest)) # No equivalent px , py , pz = position name , phone , email , * other_info = contact
• Inline type annotations are not supported: # Closest equivalent is "p: Optional[int]" as a separate declaration p : Optional [ int ] = None
• Augmented assignment is not supported: total += tax # Equivalent: (total := total + tax)

The following changes have been made based on implementation experience and additional review after the PEP was first accepted and before Python 3.8 was released:

• for consistency with other similar exceptions, and to avoid locking in an exception name that is not necessarily going to improve clarity for end users, the originally proposed TargetScopeError subclass of SyntaxError was dropped in favour of just raising SyntaxError directly. [3]
• due to a limitation in CPython’s symbol table analysis process, the reference implementation raises SyntaxError for all uses of named expressions inside comprehension iterable expressions, rather than only raising them when the named expression target conflicts with one of the iteration variables in the comprehension. This could be revisited given sufficiently compelling examples, but the extra complexity needed to implement the more selective restriction doesn’t seem worthwhile for purely hypothetical use cases.

Examples from the Python standard library

env_base is only used on these lines, putting its assignment on the if moves it as the “header” of the block.

• Current: env_base = os . environ . get ( "PYTHONUSERBASE" , None ) if env_base : return env_base
• Improved: if env_base := os . environ . get ( "PYTHONUSERBASE" , None ): return env_base

Avoid nested if and remove one indentation level.

• Current: if self . _is_special : ans = self . _check_nans ( context = context ) if ans : return ans
• Improved: if self . _is_special and ( ans := self . _check_nans ( context = context )): return ans

Code looks more regular and avoid multiple nested if. (See Appendix A for the origin of this example.)

• Current: reductor = dispatch_table . get ( cls ) if reductor : rv = reductor ( x ) else : reductor = getattr ( x , "__reduce_ex__" , None ) if reductor : rv = reductor ( 4 ) else : reductor = getattr ( x , "__reduce__" , None ) if reductor : rv = reductor () else : raise Error ( "un(deep)copyable object of type %s " % cls )
• Improved: if reductor := dispatch_table . get ( cls ): rv = reductor ( x ) elif reductor := getattr ( x , "__reduce_ex__" , None ): rv = reductor ( 4 ) elif reductor := getattr ( x , "__reduce__" , None ): rv = reductor () else : raise Error ( "un(deep)copyable object of type %s " % cls )

tz is only used for s += tz , moving its assignment inside the if helps to show its scope.

• Current: s = _format_time ( self . _hour , self . _minute , self . _second , self . _microsecond , timespec ) tz = self . _tzstr () if tz : s += tz return s
• Improved: s = _format_time ( self . _hour , self . _minute , self . _second , self . _microsecond , timespec ) if tz := self . _tzstr (): s += tz return s

Calling fp.readline() in the while condition and calling .match() on the if lines make the code more compact without making it harder to understand.

• Current: while True : line = fp . readline () if not line : break m = define_rx . match ( line ) if m : n , v = m . group ( 1 , 2 ) try : v = int ( v ) except ValueError : pass vars [ n ] = v else : m = undef_rx . match ( line ) if m : vars [ m . group ( 1 )] = 0
• Improved: while line := fp . readline (): if m := define_rx . match ( line ): n , v = m . group ( 1 , 2 ) try : v = int ( v ) except ValueError : pass vars [ n ] = v elif m := undef_rx . match ( line ): vars [ m . group ( 1 )] = 0

A list comprehension can map and filter efficiently by capturing the condition:

Similarly, a subexpression can be reused within the main expression, by giving it a name on first use:

Note that in both cases the variable y is bound in the containing scope (i.e. at the same level as results or stuff ).

Assignment expressions can be used to good effect in the header of an if or while statement:

Particularly with the while loop, this can remove the need to have an infinite loop, an assignment, and a condition. It also creates a smooth parallel between a loop which simply uses a function call as its condition, and one which uses that as its condition but also uses the actual value.

An example from the low-level UNIX world:

Rejected alternative proposals

Proposals broadly similar to this one have come up frequently on python-ideas. Below are a number of alternative syntaxes, some of them specific to comprehensions, which have been rejected in favour of the one given above.

A previous version of this PEP proposed subtle changes to the scope rules for comprehensions, to make them more usable in class scope and to unify the scope of the “outermost iterable” and the rest of the comprehension. However, this part of the proposal would have caused backwards incompatibilities, and has been withdrawn so the PEP can focus on assignment expressions.

Broadly the same semantics as the current proposal, but spelled differently.

Since EXPR as NAME already has meaning in import , except and with statements (with different semantics), this would create unnecessary confusion or require special-casing (e.g. to forbid assignment within the headers of these statements).

(Note that with EXPR as VAR does not simply assign the value of EXPR to VAR – it calls EXPR.__enter__() and assigns the result of that to VAR .)

Additional reasons to prefer := over this spelling include:

• In if f(x) as y the assignment target doesn’t jump out at you – it just reads like if f x blah blah and it is too similar visually to if f(x) and y .
• import foo as bar
• except Exc as var
• with ctxmgr() as var

To the contrary, the assignment expression does not belong to the if or while that starts the line, and we intentionally allow assignment expressions in other contexts as well.

• NAME = EXPR
• if NAME := EXPR

reinforces the visual recognition of assignment expressions.

This syntax is inspired by languages such as R and Haskell, and some programmable calculators. (Note that a left-facing arrow y <- f(x) is not possible in Python, as it would be interpreted as less-than and unary minus.) This syntax has a slight advantage over ‘as’ in that it does not conflict with with , except and import , but otherwise is equivalent. But it is entirely unrelated to Python’s other use of -> (function return type annotations), and compared to := (which dates back to Algol-58) it has a much weaker tradition.

This has the advantage that leaked usage can be readily detected, removing some forms of syntactic ambiguity. However, this would be the only place in Python where a variable’s scope is encoded into its name, making refactoring harder.

Execution order is inverted (the indented body is performed first, followed by the “header”). This requires a new keyword, unless an existing keyword is repurposed (most likely with: ). See PEP 3150 for prior discussion on this subject (with the proposed keyword being given: ).

This syntax has fewer conflicts than as does (conflicting only with the raise Exc from Exc notation), but is otherwise comparable to it. Instead of paralleling with expr as target: (which can be useful but can also be confusing), this has no parallels, but is evocative.

One of the most popular use-cases is if and while statements. Instead of a more general solution, this proposal enhances the syntax of these two statements to add a means of capturing the compared value:

This works beautifully if and ONLY if the desired condition is based on the truthiness of the captured value. It is thus effective for specific use-cases (regex matches, socket reads that return '' when done), and completely useless in more complicated cases (e.g. where the condition is f(x) < 0 and you want to capture the value of f(x) ). It also has no benefit to list comprehensions.

Advantages: No syntactic ambiguities. Disadvantages: Answers only a fraction of possible use-cases, even in if / while statements.

Another common use-case is comprehensions (list/set/dict, and genexps). As above, proposals have been made for comprehension-specific solutions.

This brings the subexpression to a location in between the ‘for’ loop and the expression. It introduces an additional language keyword, which creates conflicts. Of the three, where reads the most cleanly, but also has the greatest potential for conflict (e.g. SQLAlchemy and numpy have where methods, as does tkinter.dnd.Icon in the standard library).

As above, but reusing the with keyword. Doesn’t read too badly, and needs no additional language keyword. Is restricted to comprehensions, though, and cannot as easily be transformed into “longhand” for-loop syntax. Has the C problem that an equals sign in an expression can now create a name binding, rather than performing a comparison. Would raise the question of why “with NAME = EXPR:” cannot be used as a statement on its own.

As per option 2, but using as rather than an equals sign. Aligns syntactically with other uses of as for name binding, but a simple transformation to for-loop longhand would create drastically different semantics; the meaning of with inside a comprehension would be completely different from the meaning as a stand-alone statement, while retaining identical syntax.

Regardless of the spelling chosen, this introduces a stark difference between comprehensions and the equivalent unrolled long-hand form of the loop. It is no longer possible to unwrap the loop into statement form without reworking any name bindings. The only keyword that can be repurposed to this task is with , thus giving it sneakily different semantics in a comprehension than in a statement; alternatively, a new keyword is needed, with all the costs therein.

There are two logical precedences for the := operator. Either it should bind as loosely as possible, as does statement-assignment; or it should bind more tightly than comparison operators. Placing its precedence between the comparison and arithmetic operators (to be precise: just lower than bitwise OR) allows most uses inside while and if conditions to be spelled without parentheses, as it is most likely that you wish to capture the value of something, then perform a comparison on it:

Once find() returns -1, the loop terminates. If := binds as loosely as = does, this would capture the result of the comparison (generally either True or False ), which is less useful.

While this behaviour would be convenient in many situations, it is also harder to explain than “the := operator behaves just like the assignment statement”, and as such, the precedence for := has been made as close as possible to that of = (with the exception that it binds tighter than comma).

Some critics have claimed that the assignment expressions should allow unparenthesized tuples on the right, so that these two would be equivalent:

(With the current version of the proposal, the latter would be equivalent to ((point := x), y) .)

However, adopting this stance would logically lead to the conclusion that when used in a function call, assignment expressions also bind less tight than comma, so we’d have the following confusing equivalence:

The less confusing option is to make := bind more tightly than comma.

It’s been proposed to just always require parentheses around an assignment expression. This would resolve many ambiguities, and indeed parentheses will frequently be needed to extract the desired subexpression. But in the following cases the extra parentheses feel redundant:

Frequently Raised Objections

C and its derivatives define the = operator as an expression, rather than a statement as is Python’s way. This allows assignments in more contexts, including contexts where comparisons are more common. The syntactic similarity between if (x == y) and if (x = y) belies their drastically different semantics. Thus this proposal uses := to clarify the distinction.

The two forms have different flexibilities. The := operator can be used inside a larger expression; the = statement can be augmented to += and its friends, can be chained, and can assign to attributes and subscripts.

Previous revisions of this proposal involved sublocal scope (restricted to a single statement), preventing name leakage and namespace pollution. While a definite advantage in a number of situations, this increases complexity in many others, and the costs are not justified by the benefits. In the interests of language simplicity, the name bindings created here are exactly equivalent to any other name bindings, including that usage at class or module scope will create externally-visible names. This is no different from for loops or other constructs, and can be solved the same way: del the name once it is no longer needed, or prefix it with an underscore.

(The author wishes to thank Guido van Rossum and Christoph Groth for their suggestions to move the proposal in this direction. [2] )

As expression assignments can sometimes be used equivalently to statement assignments, the question of which should be preferred will arise. For the benefit of style guides such as PEP 8 , two recommendations are suggested.

• If either assignment statements or assignment expressions can be used, prefer statements; they are a clear declaration of intent.
• If using assignment expressions would lead to ambiguity about execution order, restructure it to use statements instead.

The authors wish to thank Alyssa Coghlan and Steven D’Aprano for their considerable contributions to this proposal, and members of the core-mentorship mailing list for assistance with implementation.

Appendix A: Tim Peters’s findings

Here’s a brief essay Tim Peters wrote on the topic.

I dislike “busy” lines of code, and also dislike putting conceptually unrelated logic on a single line. So, for example, instead of:

instead. So I suspected I’d find few places I’d want to use assignment expressions. I didn’t even consider them for lines already stretching halfway across the screen. In other cases, “unrelated” ruled:

is a vast improvement over the briefer:

The original two statements are doing entirely different conceptual things, and slamming them together is conceptually insane.

In other cases, combining related logic made it harder to understand, such as rewriting:

as the briefer:

The while test there is too subtle, crucially relying on strict left-to-right evaluation in a non-short-circuiting or method-chaining context. My brain isn’t wired that way.

But cases like that were rare. Name binding is very frequent, and “sparse is better than dense” does not mean “almost empty is better than sparse”. For example, I have many functions that return None or 0 to communicate “I have nothing useful to return in this case, but since that’s expected often I’m not going to annoy you with an exception”. This is essentially the same as regular expression search functions returning None when there is no match. So there was lots of code of the form:

I find that clearer, and certainly a bit less typing and pattern-matching reading, as:

It’s also nice to trade away a small amount of horizontal whitespace to get another _line_ of surrounding code on screen. I didn’t give much weight to this at first, but it was so very frequent it added up, and I soon enough became annoyed that I couldn’t actually run the briefer code. That surprised me!

There are other cases where assignment expressions really shine. Rather than pick another from my code, Kirill Balunov gave a lovely example from the standard library’s copy() function in copy.py :

The ever-increasing indentation is semantically misleading: the logic is conceptually flat, “the first test that succeeds wins”:

Using easy assignment expressions allows the visual structure of the code to emphasize the conceptual flatness of the logic; ever-increasing indentation obscured it.

A smaller example from my code delighted me, both allowing to put inherently related logic in a single line, and allowing to remove an annoying “artificial” indentation level:

That if is about as long as I want my lines to get, but remains easy to follow.

So, in all, in most lines binding a name, I wouldn’t use assignment expressions, but because that construct is so very frequent, that leaves many places I would. In most of the latter, I found a small win that adds up due to how often it occurs, and in the rest I found a moderate to major win. I’d certainly use it more often than ternary if , but significantly less often than augmented assignment.

I have another example that quite impressed me at the time.

Where all variables are positive integers, and a is at least as large as the n’th root of x, this algorithm returns the floor of the n’th root of x (and roughly doubling the number of accurate bits per iteration):

It’s not obvious why that works, but is no more obvious in the “loop and a half” form. It’s hard to prove correctness without building on the right insight (the “arithmetic mean - geometric mean inequality”), and knowing some non-trivial things about how nested floor functions behave. That is, the challenges are in the math, not really in the coding.

If you do know all that, then the assignment-expression form is easily read as “while the current guess is too large, get a smaller guess”, where the “too large?” test and the new guess share an expensive sub-expression.

To my eyes, the original form is harder to understand:

This appendix attempts to clarify (though not specify) the rules when a target occurs in a comprehension or in a generator expression. For a number of illustrative examples we show the original code, containing a comprehension, and the translation, where the comprehension has been replaced by an equivalent generator function plus some scaffolding.

Since [x for ...] is equivalent to list(x for ...) these examples all use list comprehensions without loss of generality. And since these examples are meant to clarify edge cases of the rules, they aren’t trying to look like real code.

Note: comprehensions are already implemented via synthesizing nested generator functions like those in this appendix. The new part is adding appropriate declarations to establish the intended scope of assignment expression targets (the same scope they resolve to as if the assignment were performed in the block containing the outermost comprehension). For type inference purposes, these illustrative expansions do not imply that assignment expression targets are always Optional (but they do indicate the target binding scope).

Let’s start with a reminder of what code is generated for a generator expression without assignment expression.

• Original code (EXPR usually references VAR): def f (): a = [ EXPR for VAR in ITERABLE ]
• Translation (let’s not worry about name conflicts): def f (): def genexpr ( iterator ): for VAR in iterator : yield EXPR a = list ( genexpr ( iter ( ITERABLE )))

Let’s add a simple assignment expression.

• Original code: def f (): a = [ TARGET := EXPR for VAR in ITERABLE ]
• Translation: def f (): if False : TARGET = None # Dead code to ensure TARGET is a local variable def genexpr ( iterator ): nonlocal TARGET for VAR in iterator : TARGET = EXPR yield TARGET a = list ( genexpr ( iter ( ITERABLE )))

Let’s add a global TARGET declaration in f() .

• Original code: def f (): global TARGET a = [ TARGET := EXPR for VAR in ITERABLE ]
• Translation: def f (): global TARGET def genexpr ( iterator ): global TARGET for VAR in iterator : TARGET = EXPR yield TARGET a = list ( genexpr ( iter ( ITERABLE )))

Or instead let’s add a nonlocal TARGET declaration in f() .

• Original code: def g (): TARGET = ... def f (): nonlocal TARGET a = [ TARGET := EXPR for VAR in ITERABLE ]
• Translation: def g (): TARGET = ... def f (): nonlocal TARGET def genexpr ( iterator ): nonlocal TARGET for VAR in iterator : TARGET = EXPR yield TARGET a = list ( genexpr ( iter ( ITERABLE )))

Finally, let’s nest two comprehensions.

• Original code: def f (): a = [[ TARGET := i for i in range ( 3 )] for j in range ( 2 )] # I.e., a = [[0, 1, 2], [0, 1, 2]] print ( TARGET ) # prints 2
• Translation: def f (): if False : TARGET = None def outer_genexpr ( outer_iterator ): nonlocal TARGET def inner_generator ( inner_iterator ): nonlocal TARGET for i in inner_iterator : TARGET = i yield i for j in outer_iterator : yield list ( inner_generator ( range ( 3 ))) a = list ( outer_genexpr ( range ( 2 ))) print ( TARGET )

Because it has been a point of confusion, note that nothing about Python’s scoping semantics is changed. Function-local scopes continue to be resolved at compile time, and to have indefinite temporal extent at run time (“full closures”). Example:

This document has been placed in the public domain.

Source: https://github.com/python/peps/blob/main/peps/pep-0572.rst

Last modified: 2023-10-11 12:05:51 GMT

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons
• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

2.3: Arithmetic Operations and Assignment Statements

• Last updated
• Save as PDF
• Page ID 206261

• Robert Belford
• University of Arkansas at Little Rock

hypothes.is tag:  s20iostpy03ualr Download Assignment:  S2020py03

Learning Objectives

Students will be able to:

• Explain each Python arithmetic operator
• Explain the meaning and use of an  assignment statement
• Explain the use of "+"  and "*" with strings and numbers
• Use the  int()   and  float()  functions to convert string input to numbers for computation
• Incorporate numeric formatting into print statements
• Recognize the four main operations of a computer within a simple Python program
• Create  input  statements in Python
• Create  Python  code that performs mathematical and string operations
• Create  Python  code that uses assignment statements
• Create  Python   code that formats numeric output

Prior Knowledge

• Understanding of Python print and input statements
• Understanding of mathematical operations
• Understanding of flowchart input symbols

Further Reading

• https://en.wikibooks.org/wiki/Non-Programmer%27s_Tutorial_for_Python_3/Hello,_World
• https://en.wikibooks.org/wiki/Non-Programmer%27s_Tutorial_for_Python_3/Who_Goes_There%3F

Model 1: Arithmetic Operators in  Python

Python includes several arithmetic operators: addition, subtraction, multiplication, two types of division, exponentiation and  mod .

Critical Thinking Questions:

1.  Draw a line between each flowchart symbol and its corresponding line of Python code. Make note of any problems.

2. Execute the print statements in the previous Python program

    a.  Next to each print statement above, write the output.     b.  What is the value of the following line of code?

    c.  Predict the values of 17%3 and 18%3 without using your computer.

3.  Explain the purpose of each arithmetic operation:

a.               +          ____________________________

b.               -           ____________________________

c.               *          ____________________________

d.               **        ____________________________

e.               /           ____________________________

f.                //          ____________________________

g.                %         ____________________________

An  assignment statement  is a line of code that uses a "=" sign. The statement stores the result of an operation performed on the right-hand side of the sign into the variable memory location on the left-hand side.

4.         Enter and execute the following lines of Python code in the editor window of your IDE (e.g. Thonny):

 a.  What are the variables in the above python program?    b.  What does the  assignment statement :  MethaneMolMs = 16  do?    c.  What happens if you replace the comma (,) in the print statements with a plus sign (+) and execute the code again?  Why does this happen?

5.    What is stored in memory after each assignment statement is executed?

Note: Concatenating Strings in python

The "+"  concatenates  the two strings stored in the variables into one string.    "+" can only be used when both operators are strings.

6.         Run the following program in the editor window of your IDE (e.g. Thonny) to see what happens if you try to use the "+" with strings instead of numbers?

   a.  The third line of code contains an assignment statement. What is stored in  fullName   when the line is executed?    b.  What is the difference between the two output lines?    c.  How could you alter your assignment statements so that  print(fullName)  gives the same output as  print(firstName,lastName)    d. Only one of the following programs will work. Which one will work, and why doesn’t the other work? Try doing this without running the programs!

   e.  Run the programs above and see if you were correct.    f.  The program that worked above results in no space between the number and the street name. How can you alter the code so that it prints properly while using a concatenation operator?

7.  Before entering the following code into the Python interpreter (Thonny IDE editor window), predict the output of this program.

Now execute it.  What is the actual output?  Is this what you thought it would do?  Explain.

8.   Let’s take a look at a python program that prompts the user for two numbers and subtracts them. 

            Execute the following code by entering it in the editor window of Thonny.

      a.   What output do you expect?       b.   What is the actual output       c.   Revise the program in the following manner:

• Between lines two and three add the following lines of code:       num1 = int(firstNumber)      num2 = int(secondNumber)
• Next, replace the statement:     difference = firstNumber – secondNumber with the statement:     difference = num1 – num2
• Execute the program again. What output did you get?

     d.  Explain the purpose of the function  int().      e.  Explain how the changes in the program produced the desired output.

Model 3: Formatting Output in  Python

There are multiple ways to format output in python. The old way is to use the string modulo %, and the new way is with a format method function.

9.  Look closely at the output for python program 7.

    a. How do you indicate the number of decimals to display using

the string modulo (%) ______________________________________________________

the format function ________________________________________________________

     b. What happens to the number if you tell it to display less decimals than are in the number, regardless of formatting method used?

     c. What type of code allows you to right justify your numbers?

10.       Execute the following code by entering it in the editor window of Thonny.

a.  Does the output look like standard output for something that has dollars and cents associated with it?

b.  Replace the last line of code with the following:

print("Total cost of laptops: $%.2f" % price)   

print("Total cost of laptops:" ,format(price, '.2f.))

                Discuss the change in the output.

c.  Replace the last line of code with the following:

print("Total cost of laptops: $",   format(price,'.2f') print("Total cost of laptops: $" ,format(price, '.2f.))

              Discuss the change in the output.

d.  Experiment with the number ".2" in the ‘0.2f’ of the print above statement by substituting the following numbers and explain the results.

                     .4         ___________________________________________________

                     .0         ___________________________________________________

                     .1         ___________________________________________________

                     .8         ___________________________________________________

e.  Now try the following numbers in the same print statement. These numbers contain a whole number and a decimal. Explain the output for each number.

                     02.5     ___________________________________________________

                     08.2     ___________________________________________________

                     03.1     ___________________________________________________

f.  Explain what each part of the format function:  format(variable,  "%n.nf")  does in a print statement where n.n represents a number.

variable ____________________________           First n _________________________

Second n_______________________                      f    _________________________

g.          Revise the print statement by changing the "f" to "d" and  laptopCost = 600 . Execute the statements and explain the output format.

            print("Total cost of laptops: %2d" % price)             print("Total cost of laptops: %10d" % price)

h.         Explain how the function  format(var,'10d')  formats numeric data.  var  represents a whole number.

11.    Use the following program and output to answer the questions below.

a.   From the code and comments in the previous program, explain how the four main operations are implemented in this program. b.  There is one new function in this sample program.  What is it? From the corresponding output, determine what it does.

Application Questions: Use the Python Interpreter to check your work

• 8 to the 4 th  power
• The sum of 5 and 6 multiplied by the quotient of 34 and 7 using floating point arithmetic  
• Write an assignment statement that stores the remainder obtained from dividing 87 and 8 in the variable  leftover  
• Assume:  

courseLabel = "CHEM" courseNumber = "3350"

Write a line of Python code that concatenates the label with the number and stores the result in the variable  courseName . Be sure that there is a space between the course label and the course number when they are concatenated.

• Write one line of Python code that will print the word "Happy!" one hundred times.  
• Write one line of code that calculates the cost of 15 items and stores the result in the variable  totalCost
• Write one line of code that prints the total cost with a label, a dollar sign, and exactly two decimal places.  Sample output:  Total cost: $22.5  
• Assume: 

height1 = 67850 height2 = 456

Use Python formatting to write two print statements that will produce the following output exactly at it appears below:

Homework Assignment: s2020py03

Download the assignment from the website, fill out the word document, and upload to your Google Drive folder the completed assignment along with the two python files.

1. (5 pts)  Write a Python program that prompts the user for two numbers, and then gives the sum and product of those two numbers. Your sample output should look like this:

Enter your first number:10 Enter your second number:2 The sum of these numbers is: 12 The product of these two numbers is: 20

• Your program must contain documentation lines that include your name, the date, a line that states "Py03 Homework question 1" and a description line that indicates what the program is supposed to do. 
• Paste the code this word document and upload to your Google drive when the assignment is completed, with file name [your last name]_py03_HWQ1
• Save the program as a python file (ends with .py), with file name [your last name]_py03Q1_program and upload that to the Google Drive.

2. (10 pts) Write a program that calculates the molarity of a solution. Molarity is defined as numbers of moles per liter solvent. Your program will calculate molarity and must ask for the substance name, its molecular weight, how many grams of substance you are putting in solution, and the total volume of the solution. Report your calculated value of molarity to 3 decimal places. Your output should also be separated from the input with a line containing 80 asterixis.

Assuming you are using sodium chloride, your input and output should look like:

• Your program must contain documentation lines that include your name, the date, a line that states "Py03 Homework question 2" and a description line that indicates what the program is supposed to do. 
• Paste the code to question two below
• Save the program as a python file (ends with .py), with file name [your last name]_py03Q2_program and upload that to the Google Drive.

3. (4 pts) Make two hypothes.is annotations dealing with external open access resources on formatting with the format function method of formatting.  These need the tag of s20iostpy03ualr .

Copyright Statement

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons
• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

4.6: Assignment Operator

• Last updated
• Save as PDF
• Page ID 29038

• Patrick McClanahan
• San Joaquin Delta College

Assignment Operator

The assignment operator allows us to change the value of a modifiable data object (for beginning programmers this typically means a variable). It is associated with the concept of moving a value into the storage location (again usually a variable). Within C++ programming language the symbol used is the equal symbol. But bite your tongue, when you see the = symbol you need to start thinking: assignment. The assignment operator has two operands. The one to the left of the operator is usually an identifier name for a variable. The one to the right of the operator is a value.

The value 21 is moved to the memory location for the variable named: age. Another way to say it: age is assigned the value 21.

The item to the right of the assignment operator is an expression. The expression will be evaluated and the answer is 14. The value 14 would assigned to the variable named: total_cousins.

The expression to the right of the assignment operator contains some identifier names. The program would fetch the values stored in those variables; add them together and get a value of 44; then assign the 44 to the total_students variable.

As we have seen, assignment operators are used to assigning value to a variable. The left side operand of the assignment operator is a variable and right side operand of the assignment operator is a value. The value on the right side must be of the same data-type of the variable on the left side otherwise the compiler will raise an error. Different types of assignment operators are shown below:

• “=” : This is the simplest assignment operator, which was discussed above. This operator is used to assign the value on the right to the variable on the left. For example: a = 10; b = 20; ch = 'y';

If initially the value 5 is stored in the variable a,  then:  (a += 6) is equal to 11.  (the same as: a = a + 6)

If initially value 8 is stored in the variable a, then (a -= 6) is equal to  2. (the same as a = a - 6)

If initially value 5 is stored in the variable a,, then (a *= 6) is equal to 30. (the same as a = a * 6)

If initially value 6 is stored in the variable a, then (a /= 2) is equal to 3. (the same as a = a / 2)

Below example illustrates the various Assignment Operators:

Definitions

 Adapted from:  "Assignment Operator"  by  Kenneth Leroy Busbee , (Download for free at http://cnx.org/contents/[email protected] ) is licensed under  CC BY 4.0

• C Programming Tutorial
• C - Overview
• C - Features
• C - History
• C - Environment Setup
• C - Program Structure
• C - Hello World
• C - Compilation Process
• C - Comments
• C - Keywords
• C - Identifiers
• C - User Input
• C - Basic Syntax
• C - Data Types
• C - Variables
• C - Integer Promotions
• C - Type Conversion
• C - Constants
• C - Literals
• C - Escape sequences
• C - Format Specifiers
• C - Storage Classes
• C - Operators
• C - Decision Making
• C - if statement
• C - if...else statement
• C - nested if statements
• C - switch statement
• C - nested switch statements
• C - While loop
• C - For loop
• C - Do...while loop
• C - Nested loop
• C - Infinite loop
• C - Break Statement
• C - Continue Statement
• C - goto Statement
• C - Functions
• C - Main Functions
• C - Return Statement
• C - Recursion
• C - Scope Rules
• C - Properties of Array
• C - Multi-Dimensional Arrays
• C - Passing Arrays to Function
• C - Return Array from Function
• C - Variable Length Arrays
• C - Pointers
• C - Pointer Arithmetics
• C - Passing Pointers to Functions
• C - Strings
• C - Array of Strings
• C - Structures
• C - Structures and Functions
• C - Arrays of Structures
• C - Pointers to Structures
• C - Self-Referential Structures
• C - Nested Structures
• C - Bit Fields
• C - Typedef
• C - Input & Output
• C - File I/O
• C - Preprocessors
• C - Header Files
• C - Type Casting
• C - Error Handling
• C - Variable Arguments
• C - Memory Management
• C - Command Line Arguments
• C Programming Resources
• C - Questions & Answers
• C - Quick Guide
• C - Useful Resources
• C - Discussion
• Selected Reading
• UPSC IAS Exams Notes
• Developer's Best Practices
• Questions and Answers
• Effective Resume Writing
• HR Interview Questions
• Computer Glossary

Assignment Operators in C

In C, the assignment operator stores a certain value in an already declared variable. A variable in C can be assigned the value in the form of a literal, another variable or an expression. The value to be assigned forms the right hand operand, whereas the variable to be assigned should be the operand to the left of = symbol, which is defined as a simple assignment operator in C. In addition, C has several augmented assignment operators.

The following table lists the assignment operators supported by the C language −

Simple assignment operator (=)

The = operator is the most frequently used operator in C. As per ANSI C standard, all the variables must be declared in the beginning. Variable declaration after the first processing statement is not allowed. You can declare a variable to be assigned a value later in the code, or you can initialize it at the time of declaration.

You can use a literal, another variable or an expression in the assignment statement.

Once a variable of a certain type is declared, it cannot be assigned a value of any other type. In such a case the C compiler reports a type mismatch error.

In C, the expressions that refer to a memory location are called "lvalue" expressions. A lvalue may appear as either the left-hand or right-hand side of an assignment.

On the other hand, the term rvalue refers to a data value that is stored at some address in memory. A rvalue is an expression that cannot have a value assigned to it which means an rvalue may appear on the right-hand side but not on the left-hand side of an assignment.

Variables are lvalues and so they may appear on the left-hand side of an assignment. Numeric literals are rvalues and so they may not be assigned and cannot appear on the left-hand side. Take a look at the following valid and invalid statements −

Augmented assignment operators

In addition to the = operator, C allows you to combine arithmetic and bitwise operators with the = symbol to form augmented or compound assignment operator. The augmented operators offer a convenient shortcut for combining arithmetic or bitwise operation with assignment.

For example, the expression a+=b has the same effect of performing a+b first and then assigning the result back to the variable a.

Similarly, the expression a<<=b has the same effect of performing a<<b first and then assigning the result back to the variable a.

Here is a C program that demonstrates the use of assignment operators in C:

When you compile and execute the above program, it produces the following result −

This browser is no longer supported.

Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.

Assignment operators (C# reference)

• 11 contributors

The assignment operator = assigns the value of its right-hand operand to a variable, a property , or an indexer element given by its left-hand operand. The result of an assignment expression is the value assigned to the left-hand operand. The type of the right-hand operand must be the same as the type of the left-hand operand or implicitly convertible to it.

The assignment operator = is right-associative, that is, an expression of the form

is evaluated as

The following example demonstrates the usage of the assignment operator with a local variable, a property, and an indexer element as its left-hand operand:

The left-hand operand of an assignment receives the value of the right-hand operand. When the operands are of value types , assignment copies the contents of the right-hand operand. When the operands are of reference types , assignment copies the reference to the object.

This is called value assignment : the value is assigned.

ref assignment

Ref assignment = ref makes its left-hand operand an alias to the right-hand operand, as the following example demonstrates:

In the preceding example, the local reference variable arrayElement is initialized as an alias to the first array element. Then, it's ref reassigned to refer to the last array element. As it's an alias, when you update its value with an ordinary assignment operator = , the corresponding array element is also updated.

The left-hand operand of ref assignment can be a local reference variable , a ref field , and a ref , out , or in method parameter. Both operands must be of the same type.

Compound assignment

For a binary operator op , a compound assignment expression of the form

is equivalent to

except that x is only evaluated once.

Compound assignment is supported by arithmetic , Boolean logical , and bitwise logical and shift operators.

Null-coalescing assignment

You can use the null-coalescing assignment operator ??= to assign the value of its right-hand operand to its left-hand operand only if the left-hand operand evaluates to null . For more information, see the ?? and ??= operators article.

Operator overloadability

A user-defined type can't overload the assignment operator. However, a user-defined type can define an implicit conversion to another type. That way, the value of a user-defined type can be assigned to a variable, a property, or an indexer element of another type. For more information, see User-defined conversion operators .

A user-defined type can't explicitly overload a compound assignment operator. However, if a user-defined type overloads a binary operator op , the op= operator, if it exists, is also implicitly overloaded.

C# language specification

For more information, see the Assignment operators section of the C# language specification .

• C# operators and expressions
• ref keyword
• Use compound assignment (style rules IDE0054 and IDE0074)

Coming soon: Throughout 2024 we will be phasing out GitHub Issues as the feedback mechanism for content and replacing it with a new feedback system. For more information see: https://aka.ms/ContentUserFeedback .

Submit and view feedback for

Additional resources

cppreference.com

Assignment operators.

Assignment and compound assignment operators are binary operators that modify the variable to their left using the value to their right.

[ edit ] Simple assignment

The simple assignment operator expressions have the form

Assignment performs implicit conversion from the value of rhs to the type of lhs and then replaces the value in the object designated by lhs with the converted value of rhs .

Assignment also returns the same value as what was stored in lhs (so that expressions such as a = b = c are possible). The value category of the assignment operator is non-lvalue (so that expressions such as ( a = b ) = c are invalid).

rhs and lhs must satisfy one of the following:

• both lhs and rhs have compatible struct or union type, or..
• rhs must be implicitly convertible to lhs , which implies
• both lhs and rhs have arithmetic types , in which case lhs may be volatile -qualified or atomic (since C11)
• both lhs and rhs have pointer to compatible (ignoring qualifiers) types, or one of the pointers is a pointer to void, and the conversion would not add qualifiers to the pointed-to type. lhs may be volatile or restrict (since C99) -qualified or atomic (since C11) .
• lhs is a (possibly qualified or atomic (since C11) ) pointer and rhs is a null pointer constant such as NULL or a nullptr_t value (since C23)

[ edit ] Notes

If rhs and lhs overlap in memory (e.g. they are members of the same union), the behavior is undefined unless the overlap is exact and the types are compatible .

Although arrays are not assignable, an array wrapped in a struct is assignable to another object of the same (or compatible) struct type.

The side effect of updating lhs is sequenced after the value computations, but not the side effects of lhs and rhs themselves and the evaluations of the operands are, as usual, unsequenced relative to each other (so the expressions such as i = ++ i ; are undefined)

Assignment strips extra range and precision from floating-point expressions (see FLT_EVAL_METHOD ).

In C++, assignment operators are lvalue expressions, not so in C.

[ edit ] Compound assignment

The compound assignment operator expressions have the form

The expression lhs @= rhs is exactly the same as lhs = lhs @ ( rhs ) , except that lhs is evaluated only once.

[ edit ] References

• C17 standard (ISO/IEC 9899:2018):
• 6.5.16 Assignment operators (p: 72-73)
• C11 standard (ISO/IEC 9899:2011):
• 6.5.16 Assignment operators (p: 101-104)
• C99 standard (ISO/IEC 9899:1999):
• 6.5.16 Assignment operators (p: 91-93)
• C89/C90 standard (ISO/IEC 9899:1990):
• 3.3.16 Assignment operators

[ edit ] See Also

Operator precedence

[ edit ] See also

• Recent changes
• Offline version
• What links here
• Related changes
• Upload file
• Special pages
• Printable version
• Permanent link
• Page information
• In other languages
• This page was last modified on 19 August 2022, at 08:36.
• This page has been accessed 54,567 times.
• Privacy policy
• About cppreference.com
• Disclaimers

• Assignment Statement

An Assignment statement is a statement that is used to set a value to the variable name in a program .

Assignment statement allows a variable to hold different types of values during its program lifespan. Another way of understanding an assignment statement is, it stores a value in the memory location which is denoted by a variable name.

The symbol used in an assignment statement is called as an operator . The symbol is ‘=’ .

Note: The Assignment Operator should never be used for Equality purpose which is double equal sign ‘==’.

The Basic Syntax of Assignment Statement in a programming language is :

variable = expression ;

variable = variable name

expression = it could be either a direct value or a math expression/formula or a function call

Few programming languages such as Java, C, C++ require data type to be specified for the variable, so that it is easy to allocate memory space and store those values during program execution.

data_type variable_name = value ;

In the above-given examples, Variable ‘a’ is assigned a value in the same statement as per its defined data type. A data type is only declared for Variable ‘b’. In the 3 rd line of code, Variable ‘a’ is reassigned the value 25. The 4 th line of code assigns the value for Variable ‘b’.

Assignment Statement Forms

This is one of the most common forms of Assignment Statements. Here the Variable name is defined, initialized, and assigned a value in the same statement. This form is generally used when we want to use the Variable quite a few times and we do not want to change its value very frequently.

Tuple Assignment

Generally, we use this form when we want to define and assign values for more than 1 variable at the same time. This saves time and is an easy method. Note that here every individual variable has a different value assigned to it.

(Code In Python)

Sequence Assignment

(Code in Python)

Multiple-target Assignment or Chain Assignment

In this format, a single value is assigned to two or more variables.

Augmented Assignment

In this format, we use the combination of mathematical expressions and values for the Variable. Other augmented Assignment forms are: &=, -=, **=, etc.

Browse more Topics Under Data Types, Variables and Constants

• Concept of Data types
• Built-in Data Types
• Constants in Programing Language 
• Access Modifier
• Variables of Built-in-Datatypes
• Declaration/Initialization of Variables
• Type Modifier

Few Rules for Assignment Statement

Few Rules to be followed while writing the Assignment Statements are:

• Variable names must begin with a letter, underscore, non-number character. Each language has its own conventions.
• The Data type defined and the variable value must match.
• A variable name once defined can only be used once in the program. You cannot define it again to store other types of value.
• If you assign a new value to an existing variable, it will overwrite the previous value and assign the new value.

FAQs on Assignment Statement

Q1. Which of the following shows the syntax of an  assignment statement ?

• variablename = expression ;
• expression = variable ;
• datatype = variablename ;
• expression = datatype variable ;

Answer – Option A.

Q2. What is an expression ?

• Same as statement
• List of statements that make up a program
• Combination of literals, operators, variables, math formulas used to calculate a value
• Numbers expressed in digits

Answer – Option C.

Q3. What are the two steps that take place when an  assignment statement  is executed?

• Evaluate the expression, store the value in the variable
• Reserve memory, fill it with value
• Evaluate variable, store the result
• Store the value in the variable, evaluate the expression.

Customize your course in 30 seconds

Which class are you in.

Data Types, Variables and Constants

• Variables in Programming Language
• Concept of Data Types
• Declaration of Variables
• Type Modifiers
• Access Modifiers
• Constants in Programming Language

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Download the App

Statements, Expressions and Operators

If the embed above does not work here is a link to the full version of the video

We need to write code that does something

• create a variable
• assign a value to a variable
• run a separate piece of code elsewhere
• print something out to the screen
• pass some value on to another piece of code

statements are the building blocks for our code that do these things. Any piece of code we write that has an effect is a statement.

An assignment statement will assign a value to a variable

A more complex assignment statement will evaluate an expression to assign a value to a variable

Multiple statements combine to create more complex functionality

Statements follow each other, and are carried out in order

Later, we’ll look at complex statements that contain other statements and have their own functionality

• loop statements that repeat code, or iterate (for, while)
• branching statements that allow code to make decisions (if, if-else)

the names of these complex statements (for, while, if, if-else) are often reserved. This means that they cannot be used for other purposes in our code - for example we usally cannot use ‘for’ as a variable name.

Expressions

Expressions are pieces of code that will be evaluated to determine their value

• a mathematical operation
• that applies operators to the values stored in variables
• and provides a result

Expressions do not have effects, they merely produce a value. Statements can contain expressions, which means that the results of expressions can be used in our statements.

The operators that we can use in expressions will depend on the programming language we are using, but will typically include:

• basic mathematical operators, for example +, -, *, /
• other mathematical operators, for example ^, %
• logical operators, for example |, &, !
• comparison operators, for example ==, <, >

Operators can be classified by how many things they operate on. Most (but not all) operators are binary, they operate on two values (or ‘operands’). Unary operators only operate on a single value. Ternary operators operate on 3 operands.

Operators can be described by where they are placed. Prefix operators appear before their operand(s). Infix operators appear between their operands. Postfix operators appear after their operands.

The mathematical operators (addition, subtraction, multiplication and division) are all binary operators and are typically (though not always) infix:

It is possible sometimes to use mathematical operators as unary operators, for example, a unary prefix ‘-’ operator

^ is sometimes used to raise a number to a higher power

though this also might be done using ‘**’, depending on the language

‘%’ is the modulus operator, it gives the result from integer division

E will contain the value 1, since 2 divides 5 twice, with 1 as a remainder.

The binary logical operators ‘and’ and ‘or’ allow you to combine boolean values (more on this later), while the unary logical operator ‘not’ allows you to negate a binary value (true becomes false, and vice versa).

Comparison operators allow you to compare values. We can test for equality (is A equal to B?) or whether a value is less than or greater than (or less than or equal to or greater than or equal to) another value.

You may occasionally see a ternary operator ‘?’, though this is not present in all languages. This has three operands, a boolean expression, a value if the expression is true and a value if the expression is false

Do not worry too much about this one at the moment, we’ll see it again later.

Some languages (but not all!) include additional operators that can shorthand some operations, for example ‘++’ or ‘–’ as increment and decrement operators. These can typically be used postfix or prefix, and are shortcuts for ‘this value +1’ or ‘this value -1’

in many languages is the same as:

Whether these operators are used as prefix or postfix determines whether they perform their function before or after expression evaluation. For example:

The prefix ‘++’ operator will be applied to A (increasing the value by 1 to 2) and then the result of that expression stored in B, so both A and B will contain the value ‘2’.

The postfix ‘++’ operator will be applied to A after the value of A has been read and stored in B, so in this example A will have the value 2, but B will contain the original value of A before the postfix increment operator was applied, so will contain ‘1’.

If an operator sits between two values, we call it ...

No, sorry, that's incorrect. A postfix operator comes *after* its operand(s), not between them.

No, sorry, that's incorrect. A prefix operator comes *before* its operand(s), not between them.

No, sorry, that's incorrect. I just made that word up. Do you like it?

Yes, correct! An operator that operates on two operands while sitting in between them is called an 'infix' operator

Any code we write that has some __effect__ is a ...

Yes, well done, that's correct.

No, sorry, that's incorrect. Expressions are evaluated to produce a result.

Next: Conditions and Branching

Previous: Variables

JS Tutorial

Js versions, js functions, js html dom, js browser bom, js web apis, js vs jquery, js graphics, js examples, js references, javascript assignment, javascript assignment operators.

Assignment operators assign values to JavaScript variables.

Shift Assignment Operators

Bitwise assignment operators, logical assignment operators, the = operator.

The Simple Assignment Operator assigns a value to a variable.

Simple Assignment Examples

The += operator.

The Addition Assignment Operator adds a value to a variable.

Addition Assignment Examples

The -= operator.

The Subtraction Assignment Operator subtracts a value from a variable.

Subtraction Assignment Example

The *= operator.

The Multiplication Assignment Operator multiplies a variable.

Multiplication Assignment Example

The **= operator.

The Exponentiation Assignment Operator raises a variable to the power of the operand.

Exponentiation Assignment Example

The /= operator.

The Division Assignment Operator divides a variable.

Division Assignment Example

The %= operator.

The Remainder Assignment Operator assigns a remainder to a variable.

Remainder Assignment Example

Advertisement

The <<= Operator

The Left Shift Assignment Operator left shifts a variable.

Left Shift Assignment Example

The >>= operator.

The Right Shift Assignment Operator right shifts a variable (signed).

Right Shift Assignment Example

The >>>= operator.

The Unsigned Right Shift Assignment Operator right shifts a variable (unsigned).

Unsigned Right Shift Assignment Example

The &= operator.

The Bitwise AND Assignment Operator does a bitwise AND operation on two operands and assigns the result to the the variable.

Bitwise AND Assignment Example

The |= operator.

The Bitwise OR Assignment Operator does a bitwise OR operation on two operands and assigns the result to the variable.

Bitwise OR Assignment Example

The ^= operator.

The Bitwise XOR Assignment Operator does a bitwise XOR operation on two operands and assigns the result to the variable.

Bitwise XOR Assignment Example

The &&= operator.

The Logical AND assignment operator is used between two values.

If the first value is true, the second value is assigned.

Logical AND Assignment Example

The &&= operator is an ES2020 feature .

The ||= Operator

The Logical OR assignment operator is used between two values.

If the first value is false, the second value is assigned.

Logical OR Assignment Example

The ||= operator is an ES2020 feature .

The ??= Operator

The Nullish coalescing assignment operator is used between two values.

If the first value is undefined or null, the second value is assigned.

Nullish Coalescing Assignment Example

The ??= operator is an ES2020 feature .

Test Yourself With Exercises

Use the correct assignment operator that will result in x being 15 (same as x = x + y ).

Start the Exercise

COLOR PICKER

Report Error

If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:

[email protected]

Top Tutorials

Top references, top examples, get certified.

• Skip to main content
• Skip to search
• Skip to select language
• Sign up for free
• English (US)

Assignment (=)

The assignment ( = ) operator is used to assign a value to a variable or property. The assignment expression itself has a value, which is the assigned value. This allows multiple assignments to be chained in order to assign a single value to multiple variables.

A valid assignment target, including an identifier or a property accessor . It can also be a destructuring assignment pattern .

An expression specifying the value to be assigned to x .

Return value

The value of y .

Thrown in strict mode if assigning to an identifier that is not declared in the scope.

Thrown in strict mode if assigning to a property that is not modifiable .

Description

The assignment operator is completely different from the equals ( = ) sign used as syntactic separators in other locations, which include:

• Initializers of var , let , and const declarations
• Default values of destructuring
• Default parameters
• Initializers of class fields

All these places accept an assignment expression on the right-hand side of the = , so if you have multiple equals signs chained together:

This is equivalent to:

Which means y must be a pre-existing variable, and x is a newly declared const variable. y is assigned the value 5 , and x is initialized with the value of the y = 5 expression, which is also 5 . If y is not a pre-existing variable, a global variable y is implicitly created in non-strict mode , or a ReferenceError is thrown in strict mode. To declare two variables within the same declaration, use:

Simple assignment and chaining

Value of assignment expressions.

The assignment expression itself evaluates to the value of the right-hand side, so you can log the value and assign to a variable at the same time.

Unqualified identifier assignment

The global object sits at the top of the scope chain. When attempting to resolve a name to a value, the scope chain is searched. This means that properties on the global object are conveniently visible from every scope, without having to qualify the names with globalThis. or window. or global. .

Because the global object has a String property ( Object.hasOwn(globalThis, "String") ), you can use the following code:

So the global object will ultimately be searched for unqualified identifiers. You don't have to type globalThis.String ; you can just type the unqualified String . To make this feature more conceptually consistent, assignment to unqualified identifiers will assume you want to create a property with that name on the global object (with globalThis. omitted), if there is no variable of the same name declared in the scope chain.

In strict mode , assignment to an unqualified identifier in strict mode will result in a ReferenceError , to avoid the accidental creation of properties on the global object.

Note that the implication of the above is that, contrary to popular misinformation, JavaScript does not have implicit or undeclared variables. It just conflates the global object with the global scope and allows omitting the global object qualifier during property creation.

Assignment with destructuring

The left-hand side of can also be an assignment pattern. This allows assigning to multiple variables at once.

For more information, see Destructuring assignment .

Specifications

Browser compatibility.

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

• Assignment operators in the JS guide
• Destructuring assignment

• Design Pattern
• Interview Q

C Control Statements

C functions, c dynamic memory, c structure union, c file handling, c preprocessor, c command line, c programming test, c interview.

• Send your Feedback to [email protected]

Help Others, Please Share

Learn Latest Tutorials

Transact-SQL

Reinforcement Learning

R Programming

React Native

Python Design Patterns

Python Pillow

Python Turtle

Preparation

Verbal Ability

Interview Questions

Company Questions

Trending Technologies

Artificial Intelligence

Cloud Computing

Data Science

Machine Learning

B.Tech / MCA

Data Structures

Operating System

Computer Network

Compiler Design

Computer Organization

Discrete Mathematics

Ethical Hacking

Computer Graphics

Software Engineering

Web Technology

Cyber Security

C Programming

Control System

Data Mining

Data Warehouse

Table of Contents

Getting started, submitting your project, using your compiler, debugging your compiler, code generation rules.

In this project, implement support for pointer variables and for control-flow constructs.

This project only needs to implement a subset of the simplec language:

• there is only one level of indirection for pointers, no need for pointers to pointers.
• there is no need to support type casting.
• no need to support arrays
• only need to support and && , or || , not ! , equality == , and less than <

It is left as a challenge for bonus points to implement more features of the language, such as multiple levels of pointers, array allocation and indexing, etc.

Project 3 and 4 can be done separately, except for the assignment statement, which is supports both assignment to variables (project 3) and assignment to dereferenced variables (project 4).

• Submission will be via GitHub by committed and pushing all of your changes to your repository to the course GitHub assignment, which graders will use for grading.

In your virtual machine, clone your repository as described in lecture , replacing USERNAME with your GitHub username.

• If the build fails, double-check that you are in the repository directory and on a correctly-configured virtual machine.
• Running ./simplec without providing input will cause the program to stop and wait for input to stdin . Use Ctrl-D to end the input (or Ctrl-C to terminate the program).
• If ./simplec is not found, be sure to prefix the program with ./ , and be sure the make step above succeeded.

Submit your project by commiting your changes and pushing them to your GitHub repository.

• Narrow down the problem by crafting a smaller version of the test case
• Go to the part of the your code that is related to the problem
• Trace step-by-step what your code really does (not what you think/hope/feel/guess/divine/intuit/reckon it does)

Be sure to unit test as you go.

Use gdb to step through your simplec output program. First, install it with

Clone and install this useful gdb assistant called peda . Make sure you have already compiled your simplec program as shown in "Using your compiler" above. Then step through the program like so:

If you've downloaded and installed peda, you will see the assembly code, registers, and stack displayed after each step.

Examples of these constructs are available in the tests/ folder of the project repo .

• pointer.simplec
• pointer2.simplec
• pointer_arithmetic.simplec
• pointer_arithmetic.s

Control-flow

• ifelse.simplec
• while.simplec
• while2.simplec

For this project, just pass through any value on the stack, i.e., just do codegen_expr(expr->castexpr.expr); .

It is left as a bonus challenge to implement different bitwidths for different types and do the appropriate conversion for the type cast.

Unary reference operator &

this operation gets the address of the variable, rather than its contents. to do so, we need to get the offset and subtract that from the base pointer and save that result in another register.

• only allow an identexpr to be referenced, i.e., make sure that the expr->unaryexpr.expr->kind is an E_identexpr
• save the base pointer to another register, e.g., rax
• like codegen_identexpr, lookup the identifier's offset in scope
• compute the address by subtracting the offset from the base pointer copy in rax
• save the result by pushing it onto the stack

Reading from dereferenced pointer with a unary dereference operator

• generate code for the expression in the derefernce expression expr->unaryexpr.expr
• retrieve the value by popping it from the stack
• use memory indirection addressing to mov the contents of the memory address computed in the dereference expression to a register, e.g., mov (%rax), %rbx
• save the result onto the stack

Assigning to dereferenced pointer in an assignment statement

• generate code for the deref on the left side of an expression
• generate code for the right-hand side of the assignment
• pop the result of the right-hand side
• pop the result of the left-hand side
• move the right-hand side's value into the address pointed to by the left-hand size using memory indirect addressing, e.g., mov %rax, (%rbx)

Control-flow constructs and Boolean operators

See Lecture 12

Relational operators

These work just like Boolean operators, except using different jump instructions.

See the reference to pick the right one. Note that the code may be easier to write by testing for the opposite case, e.g., test for >= for < to jump when the condition does not hold (just like for if statements).

https://www.felixcloutier.com/x86/jcc

• https://www.felixcloutier.com/x86/
• https://eli.thegreenplace.net/2011/09/06/stack-frame-layout-on-x86-64
• https://keleshev.com/eax-x86-register-meaning-and-history/

Author: Paul Gazzillo

Created: 2024-04-04 Thu 10:34

Golang := Vs = Exploring Assignment Operators In Go

Explore the nuances of Go's := and = operators. This article breaks down their uses, scope considerations, and best practices, helping you write clearer, more efficient Go code.

In Go, understanding the distinction between the ':=' and '=' operators is crucial for efficient coding. The ':=' operator is used for declaring and initializing a new variable, while '=' is for assigning a value to an existing variable. This nuanced difference can significantly impact the functionality and efficiency of your Go programs.

Understanding := (Short Variable Declaration)

Understanding = (assignment operator), when to use := vs =, scope considerations, type inference with :=, common pitfalls and how to avoid them, best practices, frequently asked questions.

Short variable declaration , designated by := , is a concise way to declare and initialize a variable in Go. This operator allows you to create a variable with a type inferred from the right-hand side of the expression.

For instance, consider the following code snippet:

Here, name and age are declared and initialized without explicitly stating their types ( string and int , respectively).

When To Use Short Variable Declaration

Limitations and scope.

The := operator is particularly useful in local scopes , such as within functions or blocks, where brevity and efficiency are key. It's a go-to choice for assigning initial values to variables that will be used within a limited scope .

Consider a function:

count is declared and initialized within the function's scope, making the code cleaner and more readable.

While := is convenient, it has limitations. It cannot be used for global variable declarations. Also, it's designed for declaring new variables . If you try to redeclare an already declared variable in the same scope using := , the compiler will throw an error.

For example:

In summary, := is a powerful feature in Go for efficient variable declaration and initialization, with a focus on type inference and local scope usage. Use it to write cleaner, more concise code in functions and blocks.

The assignment operator , = , in Go, is used to assign values to already declared variables. Unlike := , it does not declare a new variable but modifies the value of an existing one.

Here, age is first declared as an integer, and then 30 is assigned to it using = .

Reassignment And Existing Variables

Global and local scope.

One of the key uses of = is to reassign values to variables. This is crucial in scenarios where the value of a variable changes over time within the same scope.

In this case, count is initially 10, but is later changed to 20.

The = operator works in both global and local scopes . It is versatile and can be used anywhere in your code, provided the variable it's being assigned to has been declared.

In this snippet, globalVar is assigned a value within a function, while localVar is assigned within its local scope.

Remember, = does not infer type. The variable's type must be clear either from its declaration or context. This operator is essential for variable value management throughout your Go programs, offering flexibility in variable usage and value updates.

Understanding the Problem:

Here is the relevant code snippet:

Here's the modified code:

Choosing between := and = in Go depends on the context and the specific requirements of the code. It's crucial to understand their appropriate use cases to write efficient and error-free programs.

New Variable Declaration

Existing variable assignment, reassigning and declaring variables.

Use := when you need to declare and initialize a new variable within a local scope. This operator is a shorthand that infers the variable's type based on the value assigned.

In this example, name is a new variable declared and initialized within the function.

Use = when you are working with already declared variables . This operator is used to update or change the value of the variable.

Here, count is an existing variable, and its value is being updated.

:= is limited to local scopes , such as inside functions or blocks. It cannot be used for global variable declarations. Conversely, = can be used in both local and global scopes.

It's important to distinguish situations where you are reassigning a value to an existing variable and when you are declaring a new one. Misusing := and = can lead to compile-time errors.

In summary, := is for declaring new variables with type inference, primarily in local scopes, while = is for assigning or updating values in both local and global scopes. Proper usage of these operators is key to writing clean and efficient Go code.

Understanding the scope of variables in Go is critical when deciding between := and = . The scope determines where a variable can be accessed or modified within the program.

Local Scope And :=

Global scope and =, redeclaration and shadowing, choosing the right scope.

The := operator is restricted to local scope . It's typically used within functions or blocks to declare and initialize variables that are not needed outside of that specific context.

Here, localVariable is accessible only within the example function.

Variables declared outside of any function, in the global scope , can be accessed and modified using the = operator from anywhere in the program.

globalVariable can be accessed and modified in any function.

In Go, shadowing can occur if a local variable is declared with the same name as a global variable. This is a common issue when using := in a local scope.

In the function example , num is a new local variable, different from the global num .

It's important to choose the right scope for your variables. Use global variables sparingly, as they can lead to code that is harder to debug and maintain. Prefer local scope with := for variables that don't need to be accessed globally.

Understanding and managing scope effectively ensures that your Go programs are more maintainable, less prone to errors, and easier to understand. Proper scope management using := and = is a key aspect of effective Go programming.

Type inference is a powerful feature of Go's := operator. It allows the compiler to automatically determine the type of the variable based on the value assigned to it.

Automatic Type Deduction

Mixed type declarations, limitations of type inference, practical use in functions.

When you use := , you do not need to explicitly declare the data type of the variable. This makes the code more concise and easier to write, especially in complex functions or when dealing with multiple variables.

In these examples, the types ( string for name and int for age ) are inferred automatically.

Type inference with := also works when declaring multiple variables in a single line, each possibly having a different type.

Here, name and age are declared in one line with different inferred types.

While type inference is convenient, it is important to be aware of its limitations . The type is inferred at the time of declaration and cannot be changed later.

In this case, attempting to assign a string to balance , initially inferred as float64 , results in an error.

Type inference is particularly useful in functions, especially when dealing with return values of different types or working with complex data structures.

Here, value 's type is inferred from the return type of someCalculation .

Type inference with := simplifies variable declaration and makes Go code more readable and easier to maintain. It's a feature that, when used appropriately, can greatly enhance the efficiency of your coding process in Go.

When using := and = , there are several common pitfalls that Go programmers may encounter. Being aware of these and knowing how to avoid them is crucial for writing effective code.

Re-declaration In The Same Scope

Shadowing global variables, incorrect type inference, accidental global declarations, using = without prior declaration.

One common mistake is attempting to re-declare a variable in the same scope using := . This results in a compilation error.

To avoid this, use = for reassignment within the same scope.

Shadowing occurs when a local variable with the same name as a global variable is declared. This can lead to unexpected behavior.

To avoid shadowing, choose distinct names for local variables or explicitly use the global variable.

Another pitfall is incorrect type inference , where the inferred type is not what the programmer expected.

Always ensure the initial value accurately represents the desired type.

Using := outside of a function accidentally creates a new local variable in the global scope, which may lead to unused variables or compilation errors.

To modify a global variable, use = within functions.

Trying to use = without a prior declaration of the variable will result in an error. Ensure that the variable is declared before using = for assignment.

Declare the variable first or use := if declaring a new variable.

Avoiding these pitfalls involves careful consideration of the scope, understanding the nuances of := and = , and ensuring proper variable declarations. By being mindful of these aspects, programmers can effectively utilize both operators in Go.

Adopting best practices when using := and = in Go can significantly enhance the readability and maintainability of your code.

Clear And Concise Declarations

Minimizing global variables, consistent use of operators, avoiding unnecessary shadowing, type checking and initialization.

Use := for local variable declarations where type inference makes the code more concise. This not only saves space but also enhances readability.

This approach makes the function more readable and straightforward.

Limit the use of global variables . When necessary, use = to assign values to them and be cautious of accidental shadowing in local scopes.

Careful management of global variables helps in maintaining a clear code structure.

Be consistent in your use of := and = . Consistency aids in understanding the flow of variable declarations and assignments throughout your code.

Avoid shadowing unless intentionally used as part of the program logic. Use distinct names for local variables to prevent confusion.

Using distinct names enhances the clarity of the code.

Use := when you want to declare and initialize a variable in one line, and when the type is clear from the context. Ensure the initial value represents the desired type accurately.

This practice ensures that the type and intent of the variable are clear.

By following these best practices, you can effectively leverage the strengths of both := and = in Go, leading to code that is efficient, clear, and easy to maintain.

What distinguishes the capacity and length of a slice in Go?

In Go, a slice's capacity (cap) refers to the total number of elements the underlying array can hold, while its length (len) indicates the current number of elements in the slice. Slices are dynamic, resizing the array automatically when needed. The capacity increases as elements are appended beyond its initial limit, leading to a new, larger underlying array.

How can I stop VS Code from showing a warning about needing comments for my exported 'Agent' struct in Go?

To resolve the linter warning for your exported 'Agent' type in Go, add a comment starting with the type's name. For instance:

go // Agent represents... type Agent struct { name string categoryId int }

This warning occurs because Go's documentation generator, godoc, uses comments for auto-generating documentation. If you prefer not to export the type, declare it in lowercase:

go type agent struct { name string categoryId int }

You can find examples of documented Go projects on pkg.go.dev. If you upload your Go project to GitHub, pkg.go.dev can automatically generate its documentation using these comments. You can also include runnable code examples and more, as seen in go-doc tricks.

What is the difference between using *float64 and sql.NullFloat64 in Golang ORM for fields like latitude and longitude in a struct?

Russ Cox explains that there's no significant difference between using float64 and sql.NullFloat64. Both work fine, but sql.Null structs might express the intent more clearly. Using a pointer could give the garbage collector more to track. In debugging, sql.Null* structs display more readable values compared to pointers. Therefore, he recommends using sql.Null* structs.

Why doesn't auto-completion work for GO in VS Code with WSL terminal, despite having GO-related extensions installed?

Try enabling Go's Language Server (gopls) in VS Code settings. After enabling, restart VS Code. You may need to install or update gopls and other tools. Be aware that gopls is still in beta, so it may crash or use excessive CPU, but improvements are ongoing.

Let's see what you learned!

In Go, when should you use the := operator instead of the = operator?

Subscribe to our newsletter, subscribe to be notified of new content on marketsplash..

Charging elephant kills an American woman on 'bucket list trip' in Zambia

An American woman who was on what she had called her "last big trip" was killed when a charging elephant flipped over the car she was traveling in at a national park in Zambia .

The “aggressive” creature buffeted the vehicle carrying six tourists and a guide, tour operator Wilderness said in a statement Tuesday. It said the 79-year-old victim died after Saturday's incident on a game drive at the Kafue National Park in western Zambia.

The company did not name the victim but Rona Wells, her daughter, identified her as Gail Mattson in a post on Facebook. She said her mother died in a “tragic accident while on her dream adventure.”

A video circulating on social media apparently showing the incident shows a large elephant running toward a car, which slows down as the animal approaches its left side. The elephant then flips the vehicle over and the passengers can be heard gasping as the car rolls over.

NBC News does not know the condition or identity of the person who filmed the video.

Photos shared online of the car, which is emblazoned with the logo of the tour operator, show it tipped onto its side after the incident, with a deep dent in two of its side doors.

Wilderness, which describes itself as a “leading conservation and hospitality company” operating in eight African countries, including Zambia, did not respond to NBC News when asked to confirm the authenticity of the video and the photos.

But the tour operator’s CEO, Keith Vincent, said in the statement that the company’s “guides are all extremely well trained and experienced.”

"Sadly in this instance the terrain and vegetation was such that the guide’s route became blocked and he could not move the vehicle out of harm’s way quickly enough,” he added.

Another woman was also injured in the incident and taken to a medical facility in South Africa, the Wilderness statement said, adding that four others were treated for minor injuries.

“It’s extremely rare to see an elephant that irate,” Marlon du Toit, a wildlife photographer and safari guide, told the “TODAY” show Thursday. “Across Africa, there are thousands and thousands of guests on safari on a daily basis with no negative consequences.”

The exact cause of Mattson’s death was unclear, but the company said her body would be repatriated to her family in the United States with the support of local Zambian authorities and the U.S. Embassy in the capital, Lusaka.

“This is a tragic event and we extend our deepest condolences to the family of the guest who died,” the statement added.

NBC News has reached out to Mattson's family for further comment.

Kafue National Park is Zambia’s largest and oldest national park, according to its website, and spans an area of more than 8,000 square miles. Vast regions of the park remain unexplored and the website says it is home to a variety of untamed wildlife.

A 'bucket list trip'

Mattson spent her winters in Sun City West, Arizona, playing bridge and cards, but during the rest of the year, she "travels all over the world," her friend Brenda Biggs told NBC News. Biggs and her husband, John Longabauth, became friends with Mattson when they moved to the area 6 ½ years ago.

Longabauth said Mattson spoke to the couple about her upcoming safari trip about two weeks ago, and called it "one of her bucket list trips." He said she was very excited for the adventure.

Before she left, she gave the couple concert tickets for a show that would happen while she was traveling, telling them to enjoy the concert and "I'll see you when I get back," Longabauth recalled of the conversation.

Biggs said Mattson, who was almost 80 years old, told her that the African safari was her "my last big trip." She said Mattson was "super excited because it was like the culmination of all the trips that she had gone on."

An avid traveler, Mattson took to trips to Europe and Asia, Longabauth recalled, noting that she might have been to South America, too.

Biggs called her friend "flamboyant," "friendly" and "fabulous" and said she loved bright colors. Mattson had taken over Biggs’ job as the event planner for their 200-member bridge club, she said.

"Gail was one of the more up people you'd ever want to meet," Longabauth said. "She was always up. She was always optimistic. She was always seeing the good side of everybody."

Yuliya Talmazan is a reporter for NBC News Digital, based in London.

Rebecca Cohen is a breaking news reporter for NBC News.

Explainer-How Monday's Total Solar Eclipse Affects U.S. Grid Operators

Explainer-How Monday's Total Solar Eclipse Affects U.S. Grid Operators

FILE PHOTO: A woman jogs by power lines in Mountain View, California, U.S., August 17, 2022. REUTERS/Carlos Barria/File Photo

By Harshit Verma

(Reuters) - Electric grids across the U.S. are anticipating a rapid decline in solar generation during Monday's total solar eclipse, which will span multiple states.

NASA estimates the path of totality - when the sun is fully blocked by the moon - will last from 1:30 pm CDT (1830 GMT) to 2:35 pm CDT in the U.S.

Here's how the eclipse will affect grid operators across the country:

ERCOT (TEXAS)

The eclipse is forecast to pass Texas from 12:10 p.m. to 3:10 p.m. CDT and cause solar power generation to dip to roughly 8% of it maximum output at its peak, the Electric Reliability Council of Texas said.

ERCOT expects solar generation to drop from more than 10,000 MW to about 1300 MW over two hours, when demand will hover between 48,899 MW and 51,539 MW. Solar can account for 15% to over 20% of ERCOT's total electricity.

ERCOT does not expect to face any grid reliability issues, but said it has analyzed challenges with ramping - essentially, the process of increasing or decreasing electricity generation to match demand -- posed by the eclipse.

If it does detect reliability issues, it may decide to commit additional resources or turn to ancillary services in real time, an ERCOT spokesperson said.

Ancillary services are additional resources purchased by ERCOT a day before to balance the next day's supply and demand.

MISO (PARTS OF MIDWEST, SOUTH AND WEST)

The Midcontinent Independent System Operator, which operates the grid in all or part of 15 states in the West, Midwest and the South, would normally see 5,500 MW of solar capacity on a sunny day.

The eclipse could shrink that by 4,000 MW over 90 minutes, followed by a 3,000 MW rebound, it said. However, the grid operator doesn't anticipate reliability issues as a result.

"Solar generation will rapidly decrease then increase, resulting in a need for ramp and may cause congestion management challenges," MISO said in an operations report.

MISO plans to increase reserve requirements and will also line up extra generation that can come online quickly if needed, it said.

ISO NEW ENGLAND

ISO New England, which spans six New England states, said the eclipse's path of totality includes northern areas in its footprint. On a clear day, approximately 6,000 MW of solar power may go offline during the eclipse, it said.

Assuming a clear, sunny day, "this could represent a 92% loss of overall solar generation," the grid operator added.

Solar will be replaced by other power resources that can come online quickly such as batteries, pumped storage, or natural gas to meet demand.

NYISO (NEW YORK)

Assuming clear skies Monday, the New York Independent System Operator expects to generate 3,500 MW of solar production as the eclipse begins, which will drop to 300 MW over an hour and then rise to about 2,000 MW after it ends.

"The loss of nearly 3,000 MW of generation is significant, even when it can be anticipated, and requires additional resources to be available for the system to account for the loss," the NYISO said.

PJM (PARTS OF NORTHEAST, MIDWEST AND SOUTH)

PJM, which covers all or part of 13 states in the Midwest, Northeast and South plus Washington, D.C., expects a temporary reduction of at least 85% to 100% of production from its solar fleet. It is preparing for a reduction of 4,800 MW of grid-connected solar that would have been otherwise available, it said on Thursday.

PJM is preparing for the eclipse by deferring planned maintenance and keeping hydropower resources on standby, it said in a statement.

CAISO (CALIFORNIA)

California is farther away from the eclipse's central path of totality. Grid-scale solar generation there is expected to drop by 6,349 MW to 7,123 MW in nearly one and a half hours.

The California Independent System Operator plans to meet this challenge by ensuring sufficient natural gas and hydropower resources are available and by potentially restricting routine maintenance.

(Editing by Kavya Balaraman in Bengaluru; Editing by Liz Hampton and Costas Pitas)

Copyright 2024 Thomson Reuters .

Join the Conversation

Tags: United States , natural gas , Texas , California

America 2024

Health News Bulletin

Stay informed on the latest news on health and COVID-19 from the editors at U.S. News & World Report.

Sign in to manage your newsletters »

Sign up to receive the latest updates from U.S News & World Report and our trusted partners and sponsors. By clicking submit, you are agreeing to our Terms and Conditions & Privacy Policy .

You May Also Like

The 10 worst presidents.

U.S. News Staff Feb. 23, 2024

Cartoons on President Donald Trump

Feb. 1, 2017, at 1:24 p.m.

Photos: Obama Behind the Scenes

April 8, 2022

Photos: Who Supports Joe Biden?

March 11, 2020

RFK Jr.’s Mixed-Up Messaging on Jan. 6

Susan Milligan April 5, 2024

EXPLAINER: Rare Human Case of Bird Flu

Cecelia Smith-Schoenwalder April 5, 2024

Friday’s Northeast Earthquake, Explained

Steven Ross Johnson April 5, 2024

The Dark Clouds Looming Over the Eclipse

Blowout: Jobs Gains Defy Expectations

Tim Smart April 5, 2024

‘Unity Ticket’ a No-Go for No Labels

Cecelia Smith-Schoenwalder April 4, 2024

• Java Arrays
• Java Strings
• Java Collection
• Java 8 Tutorial
• Java Multithreading
• Java Exception Handling
• Java Programs
• Java Project
• Java Collections Interview
• Java Interview Questions
• Spring Boot
• Java Tutorial

Overview of Java

• Introduction to Java
• The Complete History of Java Programming Language
• C++ vs Java vs Python
• How to Download and Install Java for 64 bit machine?
• Setting up the environment in Java
• How to Download and Install Eclipse on Windows?
• JDK in Java
• How JVM Works - JVM Architecture?
• Differences between JDK, JRE and JVM
• Just In Time Compiler
• Difference between JIT and JVM in Java
• Difference between Byte Code and Machine Code
• How is Java platform independent?

Basics of Java

• Java Basic Syntax
• Java Hello World Program
• Java Data Types
• Primitive data type vs. Object data type in Java with Examples
• Java Identifiers

Operators in Java

• Java Variables
• Scope of Variables In Java

Wrapper Classes in Java

Input/output in java.

• How to Take Input From User in Java?
• Scanner Class in Java
• Java.io.BufferedReader Class in Java
• Difference Between Scanner and BufferedReader Class in Java
• Ways to read input from console in Java
• System.out.println in Java
• Difference between print() and println() in Java
• Formatted Output in Java using printf()
• Fast I/O in Java in Competitive Programming

Flow Control in Java

• Decision Making in Java (if, if-else, switch, break, continue, jump)
• Java if statement with Examples
• Java if-else
• Java if-else-if ladder with Examples
• Loops in Java
• For Loop in Java
• Java while loop with Examples
• Java do-while loop with Examples
• For-each loop in Java
• Continue Statement in Java
• Break statement in Java
• Usage of Break keyword in Java
• return keyword in Java
• Java Arithmetic Operators with Examples
• Java Unary Operator with Examples

Java Assignment Operators with Examples

• Java Relational Operators with Examples
• Java Logical Operators with Examples
• Java Ternary Operator with Examples
• Bitwise Operators in Java
• Strings in Java
• String class in Java
• Java.lang.String class in Java | Set 2
• Why Java Strings are Immutable?
• StringBuffer class in Java
• StringBuilder Class in Java with Examples
• String vs StringBuilder vs StringBuffer in Java
• StringTokenizer Class in Java
• StringTokenizer Methods in Java with Examples | Set 2
• StringJoiner Class in Java
• Arrays in Java
• Arrays class in Java
• Multidimensional Arrays in Java
• Different Ways To Declare And Initialize 2-D Array in Java
• Jagged Array in Java
• Final Arrays in Java
• Reflection Array Class in Java
• util.Arrays vs reflect.Array in Java with Examples

OOPS in Java

• Object Oriented Programming (OOPs) Concept in Java
• Why Java is not a purely Object-Oriented Language?
• Classes and Objects in Java
• Naming Conventions in Java
• Java Methods

Access Modifiers in Java

• Java Constructors
• Four Main Object Oriented Programming Concepts of Java

Inheritance in Java

Abstraction in java, encapsulation in java, polymorphism in java, interfaces in java.

• 'this' reference in Java
• Inheritance and Constructors in Java
• Java and Multiple Inheritance
• Interfaces and Inheritance in Java
• Association, Composition and Aggregation in Java
• Comparison of Inheritance in C++ and Java
• abstract keyword in java
• Abstract Class in Java
• Difference between Abstract Class and Interface in Java
• Control Abstraction in Java with Examples
• Difference Between Data Hiding and Abstraction in Java
• Difference between Abstraction and Encapsulation in Java with Examples
• Difference between Inheritance and Polymorphism
• Dynamic Method Dispatch or Runtime Polymorphism in Java
• Difference between Compile-time and Run-time Polymorphism in Java

Constructors in Java

• Copy Constructor in Java
• Constructor Overloading in Java
• Constructor Chaining In Java with Examples
• Private Constructors and Singleton Classes in Java

Methods in Java

• Static methods vs Instance methods in Java
• Abstract Method in Java with Examples
• Overriding in Java
• Method Overloading in Java
• Difference Between Method Overloading and Method Overriding in Java
• Differences between Interface and Class in Java
• Functional Interfaces in Java
• Nested Interface in Java
• Marker interface in Java
• Comparator Interface in Java with Examples
• Need of Wrapper Classes in Java
• Different Ways to Create the Instances of Wrapper Classes in Java
• Character Class in Java
• Java.Lang.Byte class in Java
• Java.Lang.Short class in Java
• Java.lang.Integer class in Java
• Java.Lang.Long class in Java
• Java.Lang.Float class in Java
• Java.Lang.Double Class in Java
• Java.lang.Boolean Class in Java
• Autoboxing and Unboxing in Java
• Type conversion in Java with Examples

Keywords in Java

• Java Keywords
• Important Keywords in Java
• Super Keyword in Java
• final Keyword in Java
• static Keyword in Java
• enum in Java
• transient keyword in Java
• volatile Keyword in Java
• final, finally and finalize in Java
• Public vs Protected vs Package vs Private Access Modifier in Java
• Access and Non Access Modifiers in Java

Memory Allocation in Java

• Java Memory Management
• How are Java objects stored in memory?
• Stack vs Heap Memory Allocation
• How many types of memory areas are allocated by JVM?
• Garbage Collection in Java
• Types of JVM Garbage Collectors in Java with implementation details
• Memory leaks in Java
• Java Virtual Machine (JVM) Stack Area

Classes of Java

• Understanding Classes and Objects in Java
• Singleton Method Design Pattern in Java
• Object Class in Java
• Inner Class in Java
• Throwable Class in Java with Examples

Packages in Java

• Packages In Java
• How to Create a Package in Java?
• Java.util Package in Java
• Java.lang package in Java
• Java.io Package in Java
• Java Collection Tutorial

Exception Handling in Java

• Exceptions in Java
• Types of Exception in Java with Examples
• Checked vs Unchecked Exceptions in Java
• Java Try Catch Block
• Flow control in try catch finally in Java
• throw and throws in Java
• User-defined Custom Exception in Java
• Chained Exceptions in Java
• Null Pointer Exception In Java
• Exception Handling with Method Overriding in Java
• Multithreading in Java
• Lifecycle and States of a Thread in Java
• Java Thread Priority in Multithreading
• Main thread in Java
• Java.lang.Thread Class in Java
• Runnable interface in Java
• Naming a thread and fetching name of current thread in Java
• What does start() function do in multithreading in Java?
• Difference between Thread.start() and Thread.run() in Java
• Thread.sleep() Method in Java With Examples
• Synchronization in Java
• Importance of Thread Synchronization in Java
• Method and Block Synchronization in Java
• Lock framework vs Thread synchronization in Java
• Difference Between Atomic, Volatile and Synchronized in Java
• Deadlock in Java Multithreading
• Deadlock Prevention And Avoidance
• Difference Between Lock and Monitor in Java Concurrency
• Reentrant Lock in Java

File Handling in Java

• Java.io.File Class in Java
• Java Program to Create a New File
• Different ways of Reading a text file in Java
• Java Program to Write into a File
• Delete a File Using Java
• File Permissions in Java
• FileWriter Class in Java
• Java.io.FileDescriptor in Java
• Java.io.RandomAccessFile Class Method | Set 1
• Regular Expressions in Java
• Regex Tutorial - How to write Regular Expressions?
• Matcher pattern() method in Java with Examples
• Pattern pattern() method in Java with Examples
• Quantifiers in Java
• java.lang.Character class methods | Set 1
• Java IO : Input-output in Java with Examples
• Java.io.Reader class in Java
• Java.io.Writer Class in Java
• Java.io.FileInputStream Class in Java
• FileOutputStream in Java
• Java.io.BufferedOutputStream class in Java
• Java Networking
• TCP/IP Model
• User Datagram Protocol (UDP)
• Differences between IPv4 and IPv6
• Difference between Connection-oriented and Connection-less Services
• Socket Programming in Java
• java.net.ServerSocket Class in Java
• URL Class in Java with Examples

JDBC - Java Database Connectivity

• Introduction to JDBC (Java Database Connectivity)
• JDBC Drivers
• Establishing JDBC Connection in Java
• Types of Statements in JDBC
• JDBC Tutorial
• Java 8 Features - Complete Tutorial

Operators constitute the basic building block of any programming language. Java too provides many types of operators which can be used according to the need to perform various calculations and functions, be it logical, arithmetic, relational, etc. They are classified based on the functionality they provide.

Types of Operators: 

• Arithmetic Operators
• Unary Operators
• Assignment Operator
• Relational Operators
• Logical Operators
• Ternary Operator
• Bitwise Operators
• Shift Operators

This article explains all that one needs to know regarding Assignment Operators. 

Assignment Operators

These operators are used to assign values to a variable. The left side operand of the assignment operator is a variable, and the right side operand of the assignment operator is a value. The value on the right side must be of the same data type of the operand on the left side. Otherwise, the compiler will raise an error. This means that the assignment operators have right to left associativity, i.e., the value given on the right-hand side of the operator is assigned to the variable on the left. Therefore, the right-hand side value must be declared before using it or should be a constant. The general format of the assignment operator is, 

Types of Assignment Operators in Java

The Assignment Operator is generally of two types. They are:

1. Simple Assignment Operator: The Simple Assignment Operator is used with the “=” sign where the left side consists of the operand and the right side consists of a value. The value of the right side must be of the same data type that has been defined on the left side.

2. Compound Assignment Operator: The Compound Operator is used where +,-,*, and / is used along with the = operator.

Let’s look at each of the assignment operators and how they operate: 

1. (=) operator: 

This is the most straightforward assignment operator, which is used to assign the value on the right to the variable on the left. This is the basic definition of an assignment operator and how it functions. 

Syntax:  

Example:  

2. (+=) operator: 

This operator is a compound of ‘+’ and ‘=’ operators. It operates by adding the current value of the variable on the left to the value on the right and then assigning the result to the operand on the left. 

Note: The compound assignment operator in Java performs implicit type casting. Let’s consider a scenario where x is an int variable with a value of 5. int x = 5; If you want to add the double value 4.5 to the integer variable x and print its value, there are two methods to achieve this: Method 1: x = x + 4.5 Method 2: x += 4.5 As per the previous example, you might think both of them are equal. But in reality, Method 1 will throw a runtime error stating the “i ncompatible types: possible lossy conversion from double to int “, Method 2 will run without any error and prints 9 as output.

Reason for the Above Calculation

Method 1 will result in a runtime error stating “incompatible types: possible lossy conversion from double to int.” The reason is that the addition of an int and a double results in a double value. Assigning this double value back to the int variable x requires an explicit type casting because it may result in a loss of precision. Without the explicit cast, the compiler throws an error. Method 2 will run without any error and print the value 9 as output. The compound assignment operator += performs an implicit type conversion, also known as an automatic narrowing primitive conversion from double to int . It is equivalent to x = (int) (x + 4.5) , where the result of the addition is explicitly cast to an int . The fractional part of the double value is truncated, and the resulting int value is assigned back to x . It is advisable to use Method 2 ( x += 4.5 ) to avoid runtime errors and to obtain the desired output.

Same automatic narrowing primitive conversion is applicable for other compound assignment operators as well, including -= , *= , /= , and %= .

3. (-=) operator: 

This operator is a compound of ‘-‘ and ‘=’ operators. It operates by subtracting the variable’s value on the right from the current value of the variable on the left and then assigning the result to the operand on the left. 

4. (*=) operator:

 This operator is a compound of ‘*’ and ‘=’ operators. It operates by multiplying the current value of the variable on the left to the value on the right and then assigning the result to the operand on the left. 

5. (/=) operator: 

This operator is a compound of ‘/’ and ‘=’ operators. It operates by dividing the current value of the variable on the left by the value on the right and then assigning the quotient to the operand on the left. 

6. (%=) operator: 

This operator is a compound of ‘%’ and ‘=’ operators. It operates by dividing the current value of the variable on the left by the value on the right and then assigning the remainder to the operand on the left. 

Please Login to comment...

Similar reads.

• Java-Operators
• CBSE Exam Format Changed for Class 11-12: Focus On Concept Application Questions
• 10 Best Waze Alternatives in 2024 (Free)
• 10 Best Squarespace Alternatives in 2024 (Free)
• Top 10 Owler Alternatives & Competitors in 2024
• 30 OOPs Interview Questions and Answers (2024)

Improve your Coding Skills with Practice

What kind of Experience do you want to share?

• Share full article

Advertisement

Supported by

U.S. Finalizes Rule Requiring Two-Person Crews on Freight Trains

The regulation ensures that the nation’s largest freight railroads will not be able to reduce the number of workers aboard their trains from today’s status quo.

By Mark Walker

Reporting from Washington

The Biden administration announced on Tuesday that it had finalized a new rule that will require the nation’s largest freight railroads to maintain their current staffing of two crew members per train, settling a contentious issue between organized labor and the industry.

Federal regulations had not previously specified a minimum crew size, but the nation’s largest freight railroads typically have two workers on each train, an engineer and a conductor. The industry’s adoption of efficiency measures known as precision scheduled railroading had stoked fears among workers that freight rail companies would move to reduce their crews to one person per train as a way of further cutting costs.

The Federal Railroad Administration proposed requiring two-person crews in 2022, arguing that doing so would improve safety. The issue received further attention after a Norfolk Southern freight train derailed last year in East Palestine, Ohio, putting the issue of railroad safety in the spotlight. A bipartisan rail safety bill introduced in Congress in response to the derailment included a requirement for two-person crews, though the legislation has stalled .

The Norfolk Southern train, which investigators believe derailed because of an overheated wheel bearing , had three crew members on board: an engineer, a conductor and a conductor trainee.

“Common sense tells us that large freight trains, some of which can be over three miles long, should have at least two crew members on board — and now there’s a federal regulation in place to ensure trains are safely staffed,” Transportation Secretary Pete Buttigieg said in a statement. “This rule requiring safe train crew sizes is long overdue, and we are proud to deliver this change that will make workers, passengers and communities safer.”

In a statement, Edward A. Hall, the national president of the Brotherhood of Locomotive Engineers and Trainmen, said 11 states already required two-person crews. He called the administration’s action “an important step in making railroading safer in every state, rather than a piecemeal approach.”

The Association of American Railroads, a trade group that represents the major freight railroads, has long opposed mandating two-person crews, saying the federal government and unions have not provided evidence connecting crew size to safety.

In a statement, the group noted that in 2019, when President Donald J. Trump was in office, the Federal Railroad Administration abandoned a similar effort to require two-person crews, saying it could not justify the safety need for such a rule.

“F.R.A. is doubling down on an unfounded and unnecessary regulation that has no proven connection to rail safety,” said Ian Jefferies, the chief executive of the Association of American Railroads. “Instead of prioritizing data-backed solutions to build a safer future for rail, F.R.A. is looking to the past and upending the collective bargaining process.”

Mark Walker is an investigative reporter focused on transportation. He is based in Washington. More about Mark Walker

An official website of the United States government Here's how you know

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS A lock ( Lock A locked padlock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Biden-Harris Administration Approves Grant Funding to Expedite Capacity Expansion for Port of Baltimore Terminal Operator

Revised port infrastructure grant builds on Biden-Harris Administration’s ongoing work to mitigate supply chain disruptions and economic impact from the suspension of vessel traffic at the Port of Baltimore 

WASHINGTON – As part of the Biden-Harris Administration’s whole-of-government effort to tackle supply chain disruptions caused by the collapse of the Francis Scott Key Bridge, the U.S. Department of Transportation (DOT) and Baltimore County signed a revised grant agreement to enable Tradepoint Atlantic (TPA), a facility in the county, to use a previously awarded $8.26 million DOT grant to accommodate more cargo at TPA’s terminal on Sparrows Point at the Port of Baltimore. The TPA terminal is located outside the area affected by last week’s deadly collapse of Baltimore’s Francis Scott Key Bridge and continues to move cargo.    The adjustments to the previously awarded Port Infrastructure Development Program grant will enable Baltimore County and TPA to expedite paving at least 10 acres that will be used for additional cargo laydown area. In addition to facilitating the movement of roll-on/roll-off and bulk cargo, the increase in laydown area will more than double their prior capacity of 10,000 autos per month to be able to handle over 20,000 autos per month, helping to ensure continued automobile imports and exports in and out of the Port of Baltimore. Until last week’s bridge collapse that suspended normal vessel traffic, the Port of Baltimore was the top port in the country for automobile imports and exports. TPA has already begun grading work at the site and expects it will be ready to take additional cargo by the end of April.    “The Biden-Harris Administration has taken quick action finding every way to help Baltimore and the entire region get back on their feet – including last week’s release of $60 million to help Maryland begin urgent work,” said U.S. Transportation Secretary Pete Buttigieg. “We signed a revised grant agreement to allow one of the operators at the Port of Baltimore to use previously awarded federal funds to quickly expand cargo capacity at an area of the port that sits outside of the channel blocked by the collapse of Key Bridge.”

The Biden-Harris Administration continues to communicate with port, labor, and industry partners to advance collaboration at all levels.  This week DOT staff met with FLOW participants to provide an update on changes in East Coast inbound container traffic to the Port of Savannah and the Port of New York and New Jersey. In addition, the National Economic Council and the Department convened a meeting of East Coast ports to discuss cargo capacity concerns. Last Thursday, Secretary Pete Buttigieg and other Administration officials held a meeting with over 100 leaders from across the supply chain following the suspension of Port of Baltimore vessel traffic. The National Economic Council has also repeatedly convened the Supply Chain Disruptions Task Force to continue coordination of the Biden-Harris Administration’s response to supply chain impacts.

In response to the collapse, the Federal Highway Administration (FHWA) has been actively coordinating with federal, state, and local officials in the region, including the Maryland Department of Transportation, the Maryland Transportation Authority, the City of Baltimore, the U.S. Coast Guard and others. On March 28, FHWA announced the immediate availability of $60 million in “quick release” Emergency Relief (ER) funds for the Maryland Department of Transportation to rebuild the Francis Scott Key Bridge, within hours of receiving the request. These funds serve as a down payment toward initial costs, and additional Emergency Relief program funding will be made available as work continues. FHWA has remained on the ground, consulting with state and local officials, supporting the debris removal effort and providing technical assistance related to the reconstruction process.

Read more about the actions the Biden-Harris Administration is taking following the devastating collapse of the Francis Scott Key Bridge to reopen the port, rebuild the bridge, and support the people of Baltimore here .