modf

Return integral and fractional parts

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Contents

Interface
Description
Special Values
See Also
Standards
Page Comments

Interface

#include <math.h>double  modf (double value, double *iptr)
long  modfl (long double value, long double *iptr)
float  modff (float value, float *iptr)

Description

The modf functions break value into the integral and fractional parts, each of which has the same sign as the argument. They return the fractional part, and store the integral part (as a floating-point number) in the object pointed to by iptr.

Example:

Example - Return integral and fractional parts

Workings

#include <math.h>
#include <stdio.h>
int main()
{
  double x = 31415.9265, fractional, integer;
  fractional = modf(x, &integer);
  printf("%.4lf = %.4lf + %.4lf\n", x, integer, fractional);
  return 0;
}

Solution

Output:

31415.9265 = 31415.0000 + 0.9265

Special Values

modf ( ±∞, iptr) returns ±0 and stores ±∞ in the object pointed to by iptr.

modf ( NaN, iptr) returns a NaN and stores a NaN in the object pointed to by iptr.

Standards

The modf functions conform to ISO/IEC 9899:1999(E).

double	`modf` (double value, double *iptr)
long	`modfl` (long double value, long double *iptr)
float	`modff` (float value, float *iptr)