Explain the constant type qualifier in C language

Type qualifiers add special attributes to existing datatypes in C programming language.

There are three type qualifiers in C language and constant type qualifier is explained below −

Const

There are three types of constants, which are as follows −

• Literal constants

• Defined constants

• Memory constants

Literal constants − These are the unnamed constants that are used to specify data.

For example,

a=b+7 //Here ‘7’ is literal constant.

Defined constants − These constants use the preprocessor command ‘define" with #

For example, #define PI 3.1415

Memory constants − These constants use ‘C’ qualifier ‘const’, which indicates that the data cannot be changed.

The syntax is as follows −

const type identifier = value

For example,

const float pi = 3.1415

As, you can see that it simply gives a literal name.

Example

Following is the C program for constants type qualifier −

#include<stdio.h> #define PI 3.1415 main ( ){    const float cpi = 3.14    printf ("literal constant = %f",3.14);    printf ("defined constant = %f", PI);    printf ("memory constant = %f",cpi); }

Output

When the above program is executed, it produces the following result −

literal constant = 3.14 defined constant = 3.1415 memory constant = 3.14