Keywords,Constant in C

Keyword is a predefined or reserved word in C library with a fixed meaning and used to perform an internal operation. C Language supports 32 keywords.

Every Keyword exists in lower case latter like auto, break, case, const, continue, int etc.

32 Keywords in C Language

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

Types of Constant in C

It is an identifier whose value can not be changed at the execution time of program. In general constant can be used to represent as fixed values in a C program. Constants are classified into following types.

If any single character (alphabet or numeric or special symbol) is enclosed between single cotes ' ' known as single character constant.

If set of characters are enclosed between double cotes " " known as string character constant.

Declare constant

const keyword are used for declare a constant.

Syntax

const int height = 100;

Example

#include<stdio.h>
#include<conio.h>

void main()
{
const int a=10;
printf("%d",a);
a=20; // gives error you can't modify const
getch();
}