Constants in C

Constants in C

The Constants in C language is basically a value or variable that can't be changed in the program, here is an example for your understanding: 10, 20, 'a', 3.4, "c programming" etc.

There are various types of constants in the C programming language.

Here are the list of constants present in C along with an example:

Defining the constants in C

There are generally two ways by which a constant can be defined in the C programming:

1. const keyword

2. #define preprocessor

Const keyword

To define a constant in C programming, the const keyword is used.

Here is the syntax for the same:

const float PI=3.14;  

Note :Please note that the value of PI variable cannot be changed.

Here is an example depicting the same:

#include<stdio.h>   
int main()
{    
    const float PI=3.14;    
    printf("The value of PI is: %f",PI);    
    return 0;  
}     

In case, the user try to change the value of PI then a compile time error will be rendered. Here is an example depicting the same:

#include<stdio.h>    
int main()
{    
const float PI=3.14;     
PI=4.5;    
printf("The value of PI is: %f",PI);    
return 0;  
}     

define preprocessor in C programming

The #define preprocessor have the same function as of the const keyword i.e to define constant.