Figure 15.2   Implementing Output Parameters in C and C++

/*
 * Separates a number into three parts:  a sign (+, -, 
 * blank), a whole number magnitude, and a fractional part.
 */
void
separate(double  num,    /* input - value to be split       */
         char   *signp,  /* output - sign of num            */
         int    *wholep, /* output - whole number magnitude
                                     of num                 */
         double *fracp)  /* output - fractional part of num */
{
    double magnitude;    /* magnitude of num                */

    /* Determines sign of num */
    if (num < 0)
         *signp = '-';
    else if (num == 0)
         *signp = ' ';
    else
         *signp = '+';

    /* Finds magnitude of num (its absolute value) and      
       separates it into whole and fractional parts         */
    magnitude = fabs(num);
    *wholep = floor(magnitude);
    *fracp = magnitude - *wholep;
}