More functions from the <math.h> or <cmath> header files. Today it’s about the modf function.
This function returns two values. To do that, one part is returned by way of assignment (e.g., R1 = fn). The second part is return by storing the value in the second argument. (e.g., R1 = f(a,R2). It accomplishes this by using pointers.
The modf function takes a floating point number, e.g., a.b, and breaks the two apart such that R1 = b and R2 = a. R2 is the fractional part. R1 is the integral part.
From C11 standard.
// The standard library includes the system function.
// C++ standard I/O library.
// C++ math library.
printf("R1 = modf(a,R2) \n\n");
double R1, R2;
double a = 123.456;
R1 = modf(a, &R2);
printf("a = 123.456 R1 = %6.3f\tR2 = %3.f\n\n", R1, R2);
// Keep console window open.
// Return some value.
} // end main