C Reserved Words

In this tutorial, we will learn about C Reserved words or keywords. C keywords are predefined words that are already defined and have special meanings.

C Reserved Words

C Keywords are words that are part of the C Language. These words have predefined meanings and these words cannot be used as variable names in the C Program.

In the C language, there are 32 keywords defined by the ANSI C (C89/C90) standard. These keywords are reserved and have special meaning in the language. You cannot use them as identifiers (like variable names).

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

 

Some newer versions of C (like C99, C11, C18) introduce additional keywords, but the core C language (C89/C90) has 32 keywords.

The IDE software like Code::Blocks IDE highlights the C keywords with a different color. This is to increase the readability of the source code.

Example

In this example, the programmer is trying to declare and create a variable with the variable name case. However, the case is a C keyword. We cannot have the keyword as the variable name. The compiler throws an error expected identifier. The C compiler expects a valid identifier name.

 

 

Notice that the C keywords int, case, and return words are highlighted with dark blue color in the example.

 

C Tutorials

C Tutorials on this website can be found at:

• https://www.testingdocs.com/c-language-tutorial/