Absolute value in C

Absolute value describes the distance of a number on the number line from 0 without considering the direction. The absolute value of a number is always positive (distance can never be negative). Here we will develop a program to find the absolute value in C. First, we will develop a program without using any pre-defined function, and later we will develop the C program to find absolute value using the pre-defined abs() function.

Example:- The absolute value of -8 is 8. The absolute value of 5 is 5, and the absolute value of 0 is zero. Similarly, the absolute value of -18.5 is 18.5

abs() function

The abs() function returns the absolute value of an integer. This function is defined under stdlib.h header file.

Function prototype of abs():-
int abs(int x);

• Required header file:- "stdlib.h"
• parameter:- int value or int variable
• Return value:- It returns the absolute value of the given integer number.

#include<stdio.h>
#include<stdlib.h>
int main()
{
  int n;

  printf("Enter a number: ");
  scanf("%d",&n);

  n=abs(n);
  printf("Absolute value = %d\n", n);

  return 0;
}

Output for test1:-

Enter a number: -20
Absolute value = 20

Output for test2:-

Enter a number: 36
Absolute value = 36

labs() function to find absolute value in C

The labs() function is defined in the “stdlib.h” header file, and it is used to find out the absolute value of long integer number in C programming.

Function prototype:-
long int labs(long int x);

Required header file:- "stdlib.h"
Parameter:- long int value or variable
Return value:- Absolute value of the given parameter in long int type

#include<stdio.h>
#include<stdlib.h>
int main()
{
  long int n;

  printf("Enter a long integer number: ");
  scanf("%ld", &n);

  n = abs(n);
  printf("Absolute value = %ld\n", n);

  return 0;
}

Output:-

Enter a long integer number: -545514351
Absolute value = 545514351

fabs() function

It is given in “math.h” header file, and it is used to find out the absolute value of the floating-point number in C programming.

The function prototype is:-
double fabs(double x);

Required header file:- "math.h"
Parameter:- double value or variable
Return value:- Absolute value of the given parameter in double type

#include<stdio.h>
#include<math.h>
int main()
{
  double number;
  double result;

  printf("Enter a number: ");
  scanf("%lf", &number);

  result = fabs(number);
  printf("Absolute value = %lf\n", result);

  return 0;
}

Output:-

Enter a number: -51.508
Absolute value = 51.508000

Absolute value in C without using the predefined function

#include<stdio.h>
int main()
{
  double n;

  printf("Enter a number: ");
  scanf("%f",&n);

  if(n<0.0) n = -n ;

  printf("Absolute value = %f\n", n);

  return 0;
}

Output:-

Enter a number: -52.8
Absolute value = 52.800000

Enter a number: 5
Absolute value = 5.000000

In this C program, we use the if block statement. If the number is negative then convert the number into a positive number otherwise it will remain as it is. To convert the number from negative to positive the minus operator (-) can be used. Finally, the result is displayed to the screen using the printf function.

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