In C, keywords are reserved words that have special meaning to the compiler.
You cannot use them as variable names, function names, or identifiers.
List of C keywords (C89/C90 standard – 32 keywords)
auto double int struct
break else long switch
case enum register typedef
char extern return union
const float short unsigned
continue for signed void
default goto sizeof volatile
do if static while
Notes:
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These keywords are all lowercase in standard C.
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Later standards like C99 and C11 added more keywords (e.g., _Bool, inline, _Complex, _Atomic).
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Some compilers also have non-standard keywords as extensions (e.g., __asm, restrict).
