W3cubDocs

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.

`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).

The most common keywords that begin with an underscore are generally used through their convenience macros:

Also, each name that begins with a double underscore __ or an underscore followed by an uppercase letter is reserved: see identifier for details.

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

The following tokens are recognized by the preprocessor when they are used within the 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 when they are used outside the context of a preprocessor directive:

`_Pragma`(since C99).

The following additional keywords are classified as extensions and conditionally-supported:

`asm` `fortran`.