Syntax:
#include <cmath> double modf( double num, double *i );
The function modf() splits num into its integer and fraction parts. It returns the fractional part and loads the integer part into i.
C++ also provides the following overloaded forms:
#include <cmath> float modf( float num, float *i ); // same as modff() in C99 long double modf( long double num, long double *i ); // same as modfl() in C99