C++ keywords

 

C++

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

 

C++ language

General topics
Preprocessor Comments	Keywords Escape sequences
Flow control
Conditional execution statements
if	switch
Iteration statements (loops)
for range-for (C++11)	while do-while
Jump statements
continue - break	goto - return
Functions
Function declaration
Lambda function expression
inline specifier
Dynamic exception specifications (until C++17*)
noexcept specifier (C++11)
Exceptions
throw-expression try block	handler
Namespaces
Namespace declaration	Namespace aliases
Types
Fundamental types Enumeration types Function types	Class/struct types Union types
Specifiers
const/volatile decltype (C++11) auto (C++11)	constexpr (C++11) consteval (C++20) constinit (C++20)
Storage duration specifiers
Initialization
Default-initialization Value-initialization Zero-initialization Copy-initialization Direct-initialization	Aggregate initialization List-initialization (C++11)   Constant initialization Reference initialization

Expressions
Value categories Order of evaluation	Operators Operator precedence
Alternative representations
Literals
Boolean - Integer - Floating-point
Character - String - nullptr (C++11)
User-defined (C++11)
Utilities
Attributes (C++11)
Types
typedef declaration
Type alias declaration (C++11)
Casts
Implicit conversions static_cast const_cast	Explicit conversions dynamic_cast reinterpret_cast
Memory allocation
new expression	delete expression
Classes
Class declaration Constructors this pointer	Access specifiers friend specifier
Class-specific function properties
Virtual function override specifier (C++11)   final specifier (C++11)	explicit (C++11) static
Special member functions
Default constructor Copy constructor Move constructor (C++11)	Copy assignment Move assignment (C++11) Destructor
Templates
Class template Function template	Template specialization Parameter packs (C++11)
Miscellaneous
Inline assembly	History of C++

 

Keywords

alignas (C++11) alignof (C++11) and and_eq asm auto (*) bitand bitor bool break case catch char char8_t (C++20) char16_t (C++11) char32_t (C++11) class 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 delete	do double dynamic_cast else enum explicit export extern false float for friend goto if inline int long mutable namespace new noexcept (C++11)     not not_eq nullptr (C++11) operator or or_eq private protected public register	reinterpret_cast requires (C++20) return short signed sizeof (*) static static_assert (C++11) static_cast struct switch template this thread_local (C++11) throw true try typedef typeid typename union unsigned using virtual void volatile wchar_t while xor xor_eq
Identifiers with special meaning
final (C++11) import (C++20)	module (C++20) override (C++11)

 

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. As an exception, they are not considered reserved in attribute-tokens.(since C++11)

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) (2) (4) 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 (1) explicit export (1) (3) extern (1) false float for (1) friend goto if (2) (4) inline (1) int long mutable (1) namespace new noexcept (C++11) not not_eq nullptr (C++11) operator (4) or or_eq private (3) 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 or new meaning added in C++17.
• (3) — meaning changed or new meaning added 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. These keywords are also considered reserved in attribute-tokens, but some implementations handle them the same as the others.(since C++11)

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)

See also

C documentation for C keywords