#include <math.h>double modf(double x, double *iptr);
The modf() and modff() functions break the argument x into integral and fractional parts, each of which has the same sign as the argument. The modf() function stores the integral part as a double in the object pointed to by iptr. The modff() function stores the integral part as a float in the object pointed to by iptr.
Upon successful completion, modf() and modff() return the signed fractional part of x.
If x is NaN, NaN is returned and *iptr is set to NaN.
If the correct value would cause underflow to 0.0, modf() returns 0 and errno may be set to ERANGE.
An application wishing to check for error situations should set errno to 0 before calling modf(). If errno is non-zero on return, or the return value is NaN, an error has occurred.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|