MODF(3) | Library Functions Manual | MODF(3)

# NAME

`modf`, `modff`, `modfl` — extract signed integral and fractional values from floating-point number

# SYNOPSIS

Math Library (libm, -lm)
`#include <math.h>`

double
`modf`(double value, double *iptr);

float
`modff`(float value, float *iptr);

long double
`modfl`(long double value, long double *iptr);

# DESCRIPTION

The `modf`() function breaks the argument value into integral and fractional parts, each of which has the same sign as the argument. It stores the integral part as a double in the object pointed to by iptr. The `modff`() function is a single precision version of `modf`(). The `modfl`() function is an extended precision version of `modf`().

# RETURN VALUES

The `modf`(), `modff`() and `modfl`() functions return the signed fractional part of value.

# SEE ALSO

frexp(3), ldexp(3)

# STANDARDS

The `modf`() function conforms to ANSI X3.159-1989 (“ANSI C89”).

June 6, 2025 | Debian