C Tutorial/math.h/modf
modf
Item Value Header file math.h Declaratin float modff(float num, float *i);double modf(double num, double *i);long double modfl(long double num, long double *i); Function decomposes num into its integer and fractional parts. Return returns the fractional portion and place the integer part in the variable pointed to by i.
#include <math.h>
#include <stdio.h>
int main(void)
{
double i;
double f;
f = modf(10.123, &i);
printf("%f %f",i , f);
}