What are constants in C language? Can you give an example?

Constants are also called variables. Once defined, their values ​​will not change during program execution. Therefore, we can declare a variable as a constant referencing a fixed value. It is also called text. Constants must be defined using the Const keyword.

Grammar

The constant syntax used in C programming language is as follows-

const type VariableName;
(or)
const type *VariableName;

Different types of constants

Different types of constants used in C programming language The constants look like this:

• Integer constants - For example: 1,0,34,4567

• Floating point constants - For example: 0.0, 156.89, 23.456

• Octal and hexadecimal constants - For example: Hexadecimal: 0x2a, 0xaa .. Octal: 033, 024,..

• Character constants - For example: 'a', 'B', 'x'

• String constants - Example: "TutorialsPoint"

The types of constants are also shown in the diagram below:

Example 1

The following is a C program for determining the value of a number:

Demonstration

#include<stdio.h>
int main(){
   const int number=45;
   int value;
   int data;
   printf("enter the data:");
   scanf("%d",&data);
   value=number*data;
   printf("The value is: %d",value);
   return 0;
}

Output

When the above program is executed, the following results are produced -

enter the data:20
The value of number is: 900

In the above program, if we try to change the value of a number declared as a constant, it displays an error.

Example 2

Below is a C program that displays an error if we try to change the const value.

#include<stdio.h>
int main(){
   const int number=45;
   int data;
   printf("enter the data:");
   scanf("%d",&data);
   number=number*data;
   printf("The value of number is: %d",number);
   return 0;
}

Output

When the above program is executed, the following results are produced -

error

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