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====Static semantics====
Static semantics defines restrictions on the structure of valid texts that are hard or impossible to express in standard syntactic formalisms.<ref name="Aaby 2004">{{cite book |last=Aaby |first=Anthony |url=http://www.emu.edu.tr/aelci/Courses/D-318/D-318-Files/plbook/intro.htm |title=Introduction to Programming Languages |year=2004 |access-date=29 September 2012 |archive-url=https://web.archive.org/web/20121108043216/http://www.emu.edu.tr/aelci/Courses/D-318/D-318-Files/plbook/intro.htm |archive-date=8 November 2012 |url-status=dead}}</ref>{{Failed verification|date=January 2023|reason=This site says nothing about "static semantics" or any connection between semantics and "structure" or "restrictions".}} For compiled languages, static semantics essentially include those semantic rules that can be checked at compile time. Examples include checking that every [[identifier]] is declared before it is used (in languages that require such declarations) or that the labels on the arms of a [[case statement]] are distinct.<ref>Michael Lee Scott, ''Programming language pragmatics'', Edition 2, Morgan Kaufmann, 2006, {{ISBN|0-12-633951-1}}, p. 18–19</ref> Many important restrictions of this type, like checking that identifiers are used in the appropriate context (e.g. not adding an integer to a function name), or that [[subroutine]] calls have the appropriate number and type of arguments, can be enforced by defining them as rules in a [[logic]] called a [[type system]]. Other forms of [[static code analysis|static analyses]] like [[data flow analysis]] may also be part of static semantics. Programming languages such as [[Java (programming language)|Java]] and [[C Sharp (programming language)|C#]] have [[definite assignment analysis]], a form of data flow analysis, as part of their respective static semantics.<ref name=":1">{{Cite book |last=Winskel |first=Glynn |url=https://books.google.com/books?id=JzUNn6uUxm0C |title=The Formal Semantics of Programming Languages: An Introduction |date=5 February 1993 |publisher=MIT Press |isbn=978-0-262-73103-4 |language=en}}</ref>
====Dynamic semantics====
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