C++ keywords

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.

alignas (since C++11) alignof (since 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 char16_t (since C++11) char32_t (since C++11) class(1) compl concept (concepts TS) const constexpr (since C++11) const_cast continue decltype (since C++11) default(1) delete(1) do double .

dynamic_cast else enum explicit export(1) extern(1) false float for friend goto if import (modules TS) inline(1) int long module (modules TS) mutable(1) namespace new noexcept (since C++11) not not_eq nullptr (since C++11) operator or or_eq private protected public register(2) .

reinterpret_cast requires (concepts TS) return short signed sizeof(1) static static_assert (since C++11) static_cast struct(1) switch synchronized (TM TS) template this thread_local (since 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. Note: the keyword export is also used by Modules TS.
• (2) - meaning changed in C++17.

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.

override (C++11) final (C++11) transaction_safe (TM TS) transaction_safe_dynamic (TM TS).

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 defined.

ifdef ifndef define undef .

include line error pragma .

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

_Pragma(since C++11).

See also

C documentation for C keywords