Difference between revisions of "cpp/keyword"

Revision as of 21:24, 25 January 2023

This is a list of reserved keywords in C++. Since they are used by the language, these keywords are not available for re-definition or overloading.

A – C	D – P	R – Z
`alignas` (C++11) `alignof` (C++11) `and` `and_eq` `asm` `atomic_cancel` (TM TS) `atomic_commit` (TM TS) `atomic_noexcept` (TM TS) `auto` (1) `bitand` `bitor` `bool` `break` `case` `catch` `char` `char8_t` (C++20) `char16_t` (C++11) `char32_t` (C++11) `class` (1) `compl` `concept` (C++20) `const` `consteval` (C++20) `constexpr` (C++11) `constinit` (C++20) `const_cast` `continue` `co_await` (C++20) `co_return` (C++20) `co_yield` (C++20)	`decltype` (C++11) `default` (1) `delete` (1) `do` `double` `dynamic_cast` `else` `enum` `explicit` `export` (1) (3) `extern` (1) `false` `float` `for` `friend` `goto` `if` `inline` (1) `int` `long` `mutable` (1) `namespace` `new` `noexcept` (C++11) `not` `not_eq` `nullptr` (C++11) `operator` `or` `or_eq` `private` `protected` `public`	`reflexpr` (reflection TS) `register` (2) `reinterpret_cast` `requires` (C++20) `return` `short` `signed` `sizeof` (1) `static` `static_assert` (C++11) `static_cast` `struct` (1) `switch` `synchronized` (TM TS) `template` `this` (4) `thread_local` (C++11) `throw` `true` `try` `typedef` `typeid` `typename` `union` `unsigned` `using` (1) `virtual` `void` `volatile` `wchar_t` `while` `xor` `xor_eq`

(1) — meaning changed or new meaning added in C++11.
(2) — meaning changed in C++17.
(3) — meaning changed in C++20.
(4) — new meaning added in C++23.

Note that and, bitor, or, xor, compl, bitand, and_eq, or_eq, xor_eq, not, and not_eq (along with the digraphs <%, %>, <:, :>, %:, and %:%:) provide an alternative way to represent standard tokens.

In addition to keywords, there are identifiers with special meaning, which may be used as names of objects or functions, but have special meaning in certain contexts.

`final` (C++11) `override` (C++11) `transaction_safe` (TM TS) `transaction_safe_dynamic` (TM TS) `import` (C++20) `module` (C++20)

Also, all identifiers that contain a double underscore __ in any position and each identifier that begins with an underscore followed by an uppercase letter is always reserved and all identifiers that begin with an underscore are reserved for use as names in the global namespace. See identifiers for more details.

The namespace std is used to place names of the standard C++ library. See Extending namespace std for the rules about adding names to it.

The name posix is reserved for a future top-level namespace. The behavior is undefined if a program declares or defines anything in that namespace.

(since C++11)

The following tokens are recognized by the preprocessor when in context of a preprocessor directive:

`if` `elif` `else` `endif`	`ifdef` `ifndef` `elifdef` (C++23) `elifndef` (C++23)	`define` `undef` `include` `line`	`error` `warning` (C++23) `pragma`	`defined` `__has_include` (C++17) `__has_cpp_attribute` (C++20)	`export` (C++20) `import` (C++20) `module` (C++20)

The following tokens are recognized by the preprocessor outside the context of a preprocessor directive:

`_Pragma` (C++11)

@@ Line 1: / Line 1: @@
-   <nowiki>______/ \-.   _         _ __ _         _    _
+{{title|C++ keywords}}
-.-/     (    o\_//        / |..| \       / >--< \
+{{cpp/keyword/navbar}}
- |  ___  \_/\---'         \/ || \/       \|  \ |/
- |_||  |_||                |_''_|         |_||_|</nowiki>
+This is a list of reserved keywords in C++. Since they are used by the language, these keywords are not available for re-definition or overloading.
+{|class="wikitable"
+|-
+! A – C !! D – P !! R – Z
+|- style="vertical-align:top;"
+|
+{{rlt|alignas}} {{mark c++11}}<br>
+{{rlt|alignof}} {{mark c++11}}<br>
+{{rlt|and}}<br>
+{{rlt|and_eq}}<br>
+{{rlt|asm}}<br>
+{{ltt|cpp/language/transactional memory|atomic_cancel}} {{mark since tm ts}}<br>
+{{ltt|cpp/language/transactional memory|atomic_commit}} {{mark since tm ts}}<br>
+{{ltt|cpp/language/transactional memory|atomic_noexcept}} {{mark since tm ts}}<br>
+{{rlt|auto}} {{mark|1}}<br>
+{{rlt|bitand}}<br>
+{{rlt|bitor}}<br>
+{{rlt|bool}}<br>
+{{rlt|break}}<br>
+{{rlt|case}}<br>
+{{rlt|catch}}<br>
+{{rlt|char}}<br>
+{{rlt|char8_t}} {{mark c++20}}<br>
+{{rlt|char16_t}} {{mark c++11}}<br>
+{{rlt|char32_t}} {{mark c++11}}<br>
+{{rlt|class}} {{mark|1}}<br>
+{{rlt|compl}}<br>
+{{rlt|concept}} {{mark c++20}}<br>
+{{rlt|const}}<br>
+{{rlt|consteval}} {{mark c++20}}<br>
+{{rlt|constexpr}} {{mark c++11}}<br>
+{{rlt|constinit}} {{mark c++20}}<br>
+{{rlt|const_cast}}<br>
+{{rlt|continue}}<br>
+{{rlt|co_await}} {{mark c++20}}<br>
+{{rlt|co_return}} {{mark c++20}}<br>
+{{rlt|co_yield}} {{mark c++20}}<br>
+|
+{{rlt|decltype}} {{mark c++11}}<br>
+{{rlt|default}} {{mark|1}}<br>
+{{rlt|delete}} {{mark|1}}<br>
+{{rlt|do}}<br>
+{{rlt|double}}<br>
+{{rlt|dynamic_cast}}<br>
+{{rlt|else}}<br>
+{{rlt|enum}}<br>
+{{rlt|explicit}}<br>
+{{rlt|export}} {{mark|1}} {{mark|3}}<br>
+{{rlt|extern}} {{mark|1}}<br>
+{{rlt|false}}<br>
+{{rlt|float}}<br>
+{{rlt|for}}<br>
+{{rlt|friend}}<br>
+{{rlt|goto}}<br>
+{{rlt|if}}<br>
+{{rlt|inline}} {{mark|1}}<br>
+{{rlt|int}}<br>
+{{rlt|long}}<br>
+{{rlt|mutable}} {{mark|1}}<br>
+{{rlt|namespace}}<br>
+{{rlt|new}}<br>
+{{rlt|noexcept}} {{mark c++11}}<br>
+{{rlt|not}}<br>
+{{rlt|not_eq}}<br>
+{{rlt|nullptr}} {{mark c++11}}<br>
+{{rlt|operator}}<br>
+{{rlt|or}}<br>
+{{rlt|or_eq}}<br>
+{{rlt|private}}<br>
+{{rlt|protected}}<br>
+{{rlt|public}}<br>
+|
+{{rlt|reflexpr}} {{mark since reflection ts}}<br>
+{{rlt|register}} {{mark|2}}<br>
+{{rlt|reinterpret_cast}}<br>
+{{rlt|requires}} {{mark c++20}}<br>
+{{rlt|return}}<br>
+{{rlt|short}}<br>
+{{rlt|signed}}<br>
+{{rlt|sizeof}} {{mark|1}}<br>
+{{rlt|static}}<br>
+{{rlt|static_assert}} {{mark c++11}}<br>
+{{rlt|static_cast}}<br>
+{{rlt|struct}} {{mark|1}}<br>
+{{rlt|switch}}<br>
+{{ltt|cpp/language/transactional memory|synchronized}} {{mark since tm ts}}<br>
+{{rlt|template}}<br>
+{{rlt|this}} {{mark|4}}<br>
+{{rlt|thread_local}} {{mark c++11}}<br>
+{{rlt|throw}}<br>
+{{rlt|true}}<br>
+{{rlt|try}}<br>
+{{rlt|typedef}}<br>
+{{rlt|typeid}}<br>
+{{rlt|typename}}<br>
+{{rlt|union}}<br>
+{{rlt|unsigned}}<br>
+{{rlt|using}} {{mark|1}}<br>
+{{rlt|virtual}}<br>
+{{rlt|void}}<br>
+{{rlt|volatile}}<br>
+{{rlt|wchar_t}}<br>
+{{rlt|while}}<br>
+{{rlt|xor}}<br>
+{{rlt|xor_eq}}
+|}
+* {{mark|1}} — meaning changed or new meaning added in C++11.
+* {{mark|2}} — meaning changed in C++17.
+* {{mark|3}} — meaning changed in C++20.
+* {{mark|4}} — new meaning added in C++23.
+Note that {{rlt|and}}, {{rlt|bitor}}, {{rlt|or}}, {{rlt|xor}}, {{rlt|compl}}, {{rlt|bitand}}, {{rlt|and_eq}}, {{rlt|or_eq}}, {{rlt|xor_eq}}, {{rlt|not}}, and {{rlt|not_eq}} (along with the digraphs {{c|<%}}, {{c|%>}}, {{c|<:}}, {{c|:>}}, {{c|%:}}, and {{c|%:%:}}) provide an [[cpp/language/operator alternative|alternative way to represent standard tokens]].
+In addition to keywords, there are ''identifiers with special meaning'', which may be used as names of objects or functions, but have special meaning in certain contexts.
+{|class="wikitable"
+|-
+|
+{{ltt|cpp/language/final}} {{mark c++11}}<br>
+{{ltt|cpp/language/override}} {{mark c++11}}<br>
+{{ltt|cpp/language/transactional memory|transaction_safe}} {{mark since tm ts}}<br>
+{{ltt|cpp/language/transactional memory|transaction_safe_dynamic}} {{mark since tm ts}}<br>
+{{rlt|import}} {{mark c++20}}<br>
+{{rlt|module}} {{mark c++20}}
+|}
+Also, all {{lt|cpp/language/identifiers}} that contain a double underscore {{tt|__}} in any position and each identifier that begins with an underscore followed by an uppercase letter is always reserved and all identifiers that begin with an underscore are reserved for use as names in the global namespace. See {{lt|cpp/language/identifiers}} for more details.
+The namespace {{tt|std}} is used to place names of the standard C++ library. See [[cpp/language/extending std|Extending namespace std]] for the rules about adding names to it.
+{{rrev|since=c++11|The name {{tt|posix}} is reserved for a future top-level namespace. The behavior is undefined if a program declares or defines anything in that namespace.}}
+The following tokens are recognized by the {{rlp|preprocessor}} when in context of a preprocessor directive:
+{|class="wikitable"
+|-
+|
+{{ltt|cpp/preprocessor/conditional|if}}<br>
+{{ltt|cpp/preprocessor/conditional|elif}}<br>
+{{ltt|cpp/preprocessor/conditional|else}}<br>
+{{ltt|cpp/preprocessor/conditional|endif}}<br>
+|
+{{ltt|cpp/preprocessor/conditional|ifdef}}<br>
+{{ltt|cpp/preprocessor/conditional|ifndef}}<br>
+{{ltt|cpp/preprocessor/conditional|elifdef}} {{mark c++23}}<br>
+{{ltt|cpp/preprocessor/conditional|elifndef}} {{mark c++23}}<br>
+|
+{{ltt|cpp/preprocessor/replace|define}}<br>
+{{ltt|cpp/preprocessor/replace|undef}}<br>
+{{ltt|cpp/preprocessor/include|include}}<br>
+{{ltt|cpp/preprocessor/line|line}}<br>
+|
+{{ltt|cpp/preprocessor/error|error}}<br>
+{{ltt|cpp/preprocessor/error|warning}} {{mark c++23}}<br>
+{{ltt|cpp/preprocessor/impl|pragma}}<br>
+|
+{{ltt|cpp/preprocessor/conditional|defined}}<br>
+{{ltt|cpp/feature test|__has_include}} {{mark c++17}}<br>
+{{ltt|cpp/feature test|__has_cpp_attribute}} {{mark c++20}}
+|
+{{rlt|export}} {{mark c++20}}<br>
+{{rlt|import}} {{mark c++20}}<br>
+{{rlt|module}} {{mark c++20}}
+|}
+The following tokens are recognized by the {{rlp|preprocessor}} ''outside'' the context of a preprocessor directive:
+{|class="wikitable"
+|-
+|
+{{ltt|cpp/preprocessor/impl|_Pragma}} {{mark c++11}}
+|}
+===See also===
+{{dsc begin}}
+{{dsc see c|c/keyword|C keywords|nomono=true}}
+{{dsc end}}
+{{langlinks|ar|de|es|fr|it|ja|ko|pl|pt|ru|zh}}

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

cppreference.com

Namespaces

Variants

Views

Actions

Difference between revisions of "cpp/keyword"

Revision as of 21:24, 25 January 2023

See also

Navigation

Toolbox