Constant in C programming
Constant… as the name suggest that the value of variable will be remain constant throughout the program. When we declare any variable using const keyword then the variable becomes immutable which means we can’t change the value of that variable.
To declare variable as a constant we have to add const keyword before datatype during the initialization.
Syntax and Example
Syntax:
const data_type variable = value;
Example:
const int var1 = 8;
We have to set the value of constant variable during initialization because if we didn’t do it and if we declare the variable with const keyword, then variable will have garbage value through the program because it is not possible to initialize value to that variable.
Example
const int var1; // This will initialized garbage value to variable var1
var1 = 8; // This will generate an error because variable has been initialized with garbage value
Following are the types by which we can create constant variable
We can create constant variables with following keywords.
- With help of #define preprocessor directive
- With help of const keyword.
With help of #define preprocessor directive
We can set an alternate name for variable using #define.
We can also use it to create constant variable.
#define is written in Global Declarations/Definition Section part.
Syntax
#define identifier_name value
Example
#include<stdio.h>
#define var1 8
void main()
{
printf(“Value of var1 is = %d”,var1);
}
Output :
Value of var1 is = 8
With the help of const keyword
We can create constant variable using const keyword.
We have to add const keyword before datatype during initialization.
Syntax
const data_type variable = value;
Example
const int var1 = 8;
CHECKOUT OTHER RELATED TOPICS
PRACTICALS IN C PROGRAM
Programs to understand the basic data types and I/O.
Programs on Operators and Expressions.
Programs on decision statements.
Programs on looping.
Programs to understand the basic data types and I/O.
Programs on arrays.
Programs on functions.
Programs on structures and unions.
Programs on pointers.
Programs on string manipulations.
