modf man page

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

Synopsis

#include <math.h>

double modf(double x, double *iptr);

float modff(float x, float *iptr);

long double modfl(long double x, long double *iptr);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

modf(), modfl():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

Description

These functions break the argument x into an integral part and a fractional part, each of which has the same sign as x. The integral part is stored in the location pointed to by iptr.

Return Value

These functions return the fractional part of x.

If x is a NaN, a NaN is returned, and *iptr is set to a NaN.

If x is positive infinity (negative infinity), +0 (-0) is returned, and *iptr is set to positive infinity (negative infinity).

Errors

No errors occur.

Attributes

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
modf(), modff(), modfl()Thread safetyMT-Safe

Conforming to

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

See Also

frexp(3), ldexp(3)

Colophon

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Referenced By

frexp(3), ldexp(3).

modff(3) and modfl(3) are aliases of modf(3).

2016-03-15 Linux Programmer's Manual