C library - modf() function

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The C library modf(double x, double *integer) function of type double returns the fraction component (part after the decimal), and sets integer to the integer component.

Syntax

Following is the syntax of the C library function modf() −

double modf(double x, double *integer)

Parameters

This function accepts two parameters −

• x − This is the floating point value.

• integer − This is the pointer to an object where the integral part is to be stored.

Return Value

This function returns the fractional part of x, with the same sign.

Example 1: Handling postive values

Following is the basic C library function modf() to see its demonstration.

#include<stdio.h>
#include<math.h>

int main () {
   double x, fractpart, intpart;

   x = 8.123456;
   fractpart = modf(x, &intpart);

   printf("Integral part = %lf\n", intpart);
   printf("Fraction Part = %lf \n", fractpart);
   
   return(0);
}

Output

On execution of above code, we get the following result −

Integral part = 8.000000
Fraction Part = 0.123456 

Example 2: Handling negative values

Below the program calculate the integral and fractional parts of the value which is y. Also, we can replace this value with another value i.e. assigned by the users.

#include <stdio.h>
#include <math.h>

int main() {

   // Replace with your desired negative value
   double y = -8.64329; 
   double int_part, frac_part;

   frac_part = modf(y, &int_part);

   printf("Original value: %.6lf\n", y);
   printf("Integer part: %.0lf\n", int_part);
   printf("Fractional part: %.6lf\n", frac_part);

   return 0;
}

Output

After executing the code, we get the following result −

Original value: -8.643290
Integer part: -8
Fractional part: -0.643290