C Programs

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Decision Making Programs in C

Find absolute value of a number

Introduction

The absolute value of a number is its distance from zero, regardless of its sign:

• Absolute value of 5 is 5.
• Absolute value of -5 is also 5.

We can use if-else conditions or the abs() function from <stdlib.h> to calculate it.

C Program: Find Absolute Value (Using if-else)

Method 1:

#include <stdio.h>
 
int main() {
    int num, absolute;
 
    // Input number
    printf("Enter a number: ");
    scanf("%d", &num);
 
    // Check and find absolute value
    if (num < 0) {
        absolute = -num;
    } else {
        absolute = num;
    }
 
    // Display result
    printf("Absolute value of %d is %d\n", num, absolute);
 
    return 0;
}

 
OUTPUT 1 :
Enter a number: -15
Absolute value of -15 is 15

Enter a number: 23
Absolute value of 23 is 23
 

Explanation

1. User enters a number.
2. If the number is negative, we multiply by -1 to make it positive.
3. If it’s already positive, we keep it as it is.
4. The result is displayed.

Method 2: Using Built-in Function

You can also use the abs() function from <stdlib.h > :

 
#include <stdio.h>
#include <stdlib.h>  // for abs()
 
int main() {
    int num;
 
    printf("Enter a number: ");
    scanf("%d", &num);
 
    printf("Absolute value of %d is %d\n", num, abs(num));
 
    return 0;
}

 
OUTPUT 1 :
Enter a number: -15
Absolute value of -15 is 15

Enter a number: 23
Absolute value of 23 is 23