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Tokens in C

Tokens in C is the most important element to be used in creating a program in C. We can define the token as the smallest individual element in C. For `example, we cannot create a sentence without using words; similarly, we cannot create a program in C without using tokens in C. Therefore, we can say that tokens in C is the building block or the basic component for creating a program in C language.

Classification of tokens in C

Tokens in C language can be divided into the following categories:

• Keywords in C
• Identifiers in C
• Strings in C
• Operators in C
• Constant in C
• Special Characters in C

Let’s understand each token one by one.

Keywords in C

Keywords in C can be defined as the pre-defined or the reserved words having its own importance, and each keyword has its own functionality. Since keywords are the pre-defined words used by the compiler, so they cannot be used as the variable names. If the keywords are used as the variable names, it means that we are assigning a different meaning to the keyword, which is not allowed. C language supports 32 keywords given below:

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

Identifiers in C

Identifiers in C are used for naming variables, functions, arrays, structures, etc. Identifiers in C are the user-defined words. It can be composed of uppercase letters, lowercase letters, underscore, or digits, but the starting letter should be either an underscore or an alphabet. Identifiers cannot be used as keywords. Rules for constructing identifiers in C are given below:

• The first character of an identifier should be either an alphabet or an underscore, and then it can be followed by any of the character, digit, or underscore.
• It should not begin with any numerical digit.
• In identifiers, both uppercase and lowercase letters are distinct. Therefore, we can say that identifiers are case sensitive.
• Commas or blank spaces cannot be specified within an identifier.
• Keywords cannot be represented as an identifier.
• The length of the identifiers should not be more than 31 characters.
• Identifiers should be written in such a way that it is meaningful, short, and easy to read.

Strings in C

Strings in C are always represented as an array of characters having null character ‘