modf, modff, modfl - extract signed integral and fractional values from floating-point number
#include <math.h> double modf(double x, double *iptr); float modff(float x, float *iptr); long double modfl(long double x, long double *iptr);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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
These functions return the fractional part of
x is a NaN, a NaN is returned, and
*iptr is set to a NaN.
x is positive infinity (negative infinity), +0 (-0) is returned, and
*iptr is set to positive infinity (negative infinity).
No errors occur.
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD, C89.
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