C keywords

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

C keywords

auto break case char const continue default do double else enum extern

float for goto if inline int long register restrict return short

signed sizeof static struct switch typedef union unsigned void volatile while

_Alignas _Alignof _Atomic _Bool _Complex _Generic _Imaginary _Noreturn _Static_assert _Thread_local

 

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

auto break case char const continue default do double else enum extern

float for goto if inline (since C99) int long register restrict (since C99) return short

signed sizeof static struct switch typedef union unsigned void volatile while

_Alignas (since C11) _Alignof (since C11) _Atomic (since C11) _Bool (since C99) _Complex (since C99) _Generic (since C11) _Imaginary (since C99) _Noreturn (since C11) _Static_assert (since C11) _Thread_local (since C11)

Also, each name that contains a double underscore __ or begins with an underscore followed by an uppercase letter is always reserved to the implementation and should not be used as an identifier. Each name that begins with an underscore is reserved to the implementation for use as a name of a global entity; such names may be used as names of local variables, names of data members in a structure, etc.

Note that digraphs <%, %>, <:, :>, %:, and %:%: provide an alternative way to represent standard tokens.

See also

C++ documentation for C++ keywords