C - EXPRESSION, IDENTIFIERS, KEYWORDS

 EXPRESSION: -

An expression many consist of a single entity such as a constant, a variable, an array element as a reference to a function. Expressions are evaluated using an assignment statement of the form.

variable=expression;

Example:

            a*b -c,

            (mark1+marks2)/2

 

IDENTIFIERS:-

                An Identifies refer to the name of variable, functions and arrays. There are user-defined names.

Rules for an identifiers:

➢ An identifier consists of sequence of letters and digits with a letter as a first character.

➢ Both uppercase & lowercase letters are permitted, although lowercase letters we commonly used.

➢ The underscore character is also permitted in an identifier.

Example:

Valid identifiers –

roll_no, age, mark1, func1()

 

KEYWORDS:-

Keywords are the words whose meaning has already has been explained to the C compiler. The keywords cannot be used as variable names because if we do so we are trying to assign a new meaning to the keyword, which is not allowed by the computer. The keywords are also known as ‘reserved words.

There are only 32 keywords available in C.

Auto	break	case	char	const	continue	default	do
Double	else	enum	extern	float	for	goto	if
Int	long	register	return	short	signed	sizeof	static
Struct	switch	typedef	union	unsigned	void	volatile	while