C14. C Keywords

Keywords

The keywords below have special significance to C compilers and therefore can't be used as identifiers. Note that five keywords were added in C99.

auto	enum	restrict	unsigned
break	extern	return	void
case	float	short	volatile
char	for	signed	while
const	goto	sizeof	Bool
continue	if	static	Complex
default	inline	struct	Imaginary
do	int	switch
double	long	typedef
else	register	union

Because of C's case-sensitivity, keywords must appear in programs exactly as shown in above chart with all letters in lower case. Names of functions in the stan­dard library (such as printf) contain only lower-case letters also. Avoid the plight of the unfortunate programmer who enters an entire program in upper case, only to find that the compiler can't recognize keywords and calls of library func­tions.