Editing Assignment (computer science) (section)

==Notation==
{{see also|Comparison of programming languages (variable and constant declarations)}}
The two most common representations for the copying assignment are [[equals sign]] (<code>=</code>) and colon-equals (<code>:=</code>). Both forms may semantically denote either an assignment ''statement'' or an assignment ''[[operator (programming)|operator]]'' (which also has a value), depending on language and/or usage.
:{| class="wikitable"
|-
| <code>''variable'' = ''expression''</code> || [[Fortran]], [[PL/I]], [[C (programming language)|C]] (and [[:Category:C programming language family|descendants]] such as [[C++]], [[Java (programming language)|Java]], etc.), [[Bourne shell]], [[Python (programming language)|Python]], [[Go (programming language)|Go]] (assignment to pre-declared variables), [[R (programming language)|R]], [[PowerShell]], [[Nim (programming language)|Nim]], etc.
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| <code>''variable'' := ''expression''</code> || [[ALGOL]] (and derivatives), [[Simula]], [[CPL (programming language)|CPL]], [[BCPL]], [[Pascal (programming language)|Pascal]]<ref name=pascal>{{cite book |last=Moore |first=Lawrie |year=1980 |title=Foundations of Programming with Pascal |location=New York |publisher=John Wiley & Sons |isbn=0-470-26939-1}}</ref> (and descendants such as [[Modula]]), [[Mary (programming language)|Mary]], [[PL/M]], [[Ada (programming language)|Ada]], [[Smalltalk]], [[Eiffel (programming language)|Eiffel]],<ref name=eiffel1>{{cite book |last=Meyer |first=Bertrand |author-link=Bertrand Meyer |year=1992 |title=Eiffel the Language |location=Hemel Hempstead |publisher=Prentice Hall International(UK) |isbn=0-13-247925-7}}</ref><ref name=eiffel2>{{cite book |last=Wiener |first=Richard |year=1996 |title=An Object-Oriented Introduction to Computer Science Using Eiffel |location=Upper Saddle River, New Jersey |publisher=Prentice Hall |isbn=0-13-183872-5}}</ref> [[Oberon (programming language)|Oberon]], [[Dylan (programming language)|Dylan]],<ref name=dylan>{{cite book |last=Feinberg |first=Neal |author2=Keene, Sonya E.|author3= Mathews, Robert O.|author4= Withington, P. Tucker |year=1997 |title=Dylan Programming |location=Massachusetts |publisher=Addison Wesley |isbn=0-201-47976-1}}</ref> [[Seed7]], [[Python (programming language)|Python]] (an assignment expression),<ref>{{cite web|url=https://www.python.org/dev/peps/pep-0572/|title=PEP 572 &ndash; Assignment Expressions|date=28 February 2018|website=python.org|access-date=4 March 2020}}</ref> [[Go (programming language)|Go]] (shorthand for declaring and defining a variable),<ref>{{cite web|url=http://golang.org/ref/spec#Short_variable_declarations|title=The Go Programming Language Specification - The Go Programming Language|website=golang.org|access-date=20 April 2018}}</ref> [[Io (programming language)|Io]], [[AMPL]], [[ML (programming language)|ML]] (assigning to a reference value),<ref name="ml">{{cite book |last=Ullman |first=Jeffrey D. |year=1998 |title=Elements of ML Programming: ML97 Edition |location=Englewood Cliffs, New Jersey |publisher=Prentice Hall |isbn=0-13-790387-1}}</ref> [[AutoHotkey]] etc. 
|-
|}

Other possibilities include a left arrow or a keyword, though there are other, rarer, variants:

:{| class="wikitable"
|-
| <code>''variable'' << ''expression''</code> || [[Magik (programming language)|Magik]]
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| <code>''variable'' <- ''expression''</code> || [[F Sharp (programming language)|F#]], [[OCaml]], [[R (programming language)|R]], [[S (programming language)|S]]
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| <code>''variable'' <<- ''expression''</code> || [[R (programming language)|R]]
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| <code> assign("''variable''", ''expression'')</code> || [[R (programming language)|R]]
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| <code>''variable'' ← ''expression''</code> || [[APL (programming language)|APL]],<ref name="aplbook">{{cite book |last=Iverson |first=Kenneth E. |author-link=Kenneth E. Iverson |title=A Programming Language |publisher=John Wiley and Sons |year=1962 |isbn=0-471-43014-5 |url=http://www.softwarepreservation.org/projects/apl/book/APROGRAMMING%20LANGUAGE/view |access-date=2010-05-09 |archive-url=https://web.archive.org/web/20090604091725/http://www.softwarepreservation.org/projects/apl/book/APROGRAMMING%20LANGUAGE/view |archive-date=2009-06-04 |url-status=dead }}</ref> [[Smalltalk]], [[BASIC Programming|Atari 2600 BASIC Programming]]
|-
| <code>''variable'' =: ''expression''</code> || [[J (programming language)|J]]
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| <code>LET ''variable'' = ''expression''</code> || [[BASIC]]
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| <code>let ''variable'' := ''expression''</code> || [[XQuery]]
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| <code>set ''variable'' to ''expression''</code> || [[AppleScript]]
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| <code>set ''variable'' = ''expression''</code> || [[C shell]]
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| <code>Set-Variable ''variable'' ''(expression)''</code> || [[PowerShell]]
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| <code>''variable'' : ''expression''</code> || [[Macsyma|Macsyma, Maxima]], [[K (programming language)|K]]
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| <code>''variable'': ''expression''</code> || [[Rebol]]
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| <code>var ''variable'' ''expression''</code> || [[mIRC scripting language]]
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| <code>''reference-variable'' :- ''reference-expression''</code> || [[Simula]]
|}

Mathematical [[pseudocode#Common mathematical symbols|pseudo code]] assignments are generally depicted with a left-arrow.

Some platforms put the expression on the left and the variable on the right:

:{| class="wikitable"
|-
| style="padding-right: 1em" | <code>MOVE ''expression'' TO ''variable''</code> || [[COBOL]]
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| style="padding-right: 1em" | <code>''expression'' → ''variable''</code> || [[TI-BASIC]], [[Casio BASIC]]
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| style="padding-right: 1em" | <code>''expression'' -> ''variable''</code> || [[POP-2]], [[BETA (programming language)|BETA]], [[R (programming language)|R]]
|-
| style="padding-right: 1em" | <code>put ''expression'' into ''variable''</code> || [[HyperTalk]], [[LiveCode]]
|-
| style="padding-right: 1em" | <code>PUT ''expression'' IN ''variable''</code> || [[ABC (programming language)|ABC]]
|}

Some expression-oriented languages, such as [[Lisp (programming language)|Lisp]]<ref name="clisp">{{cite book |last=Graham |first=Paul |author-link=Paul Graham (computer programmer) |year=1996 |title=ANSI Common Lisp |location=New Jersey |publisher=Prentice Hall |isbn=0-13-370875-6 |url=https://archive.org/details/ansicommonlisp00grah }}</ref><ref name="cmlisp">{{cite book |last=Steele |first=Guy L. |author-link= Guy L. Steele, Jr. |year=1990 |title=Common Lisp: The Language |location=Lexington |publisher=Digital Press |isbn=1-55558-041-6}}</ref> and Tcl, uniformly use prefix (or postfix) syntax for all statements, including assignment.

:{| class="wikitable"
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| style="padding-right: 1em" | <code>(setf ''variable'' ''expression'')</code> || [[Common Lisp]]
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| <code>(set! ''variable'' ''expression'')</code> || [[Scheme (programming language)|Scheme]]<ref name="scheme">{{cite book |last=Dybvig |first=R. Kent |year=1996 |title=The Scheme Programming Language: ANSI Scheme |location=New Jersey |publisher=Prentice Hall |isbn=0-13-454646-6}}</ref><ref name="schemeint">{{cite book |last=Smith |first=Jerry D. |year=1988 |title=Introduction to Scheme |location=New Jersey |publisher=Prentice Hall |isbn=0-13-496712-7}}</ref><ref name="sussman">{{cite book |last=Abelson |first=Harold |author2=Sussman, Gerald Jay|author3= Sussman, Julie |year=1996 |title=Structure and Interpretation of Computer Programs |location=New Jersey |publisher=McGraw-Hill |isbn=0-07-000484-6}}</ref>
|-
| <code>set ''variable'' ''expression''</code> || [[Tcl]]
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| style="padding-right: 1em" | <code>''expression'' ''variable'' !</code> || [[Forth (programming language)|Forth]]
|}