/* Figure 6.5  Program That Calls a Function with Output Arguments */
/*
 * Demonstrates the use of a function with input and output parameters.
 */

#include <stdio.h>
#include <math.h>

void separate(double num, char *signp, int *wholep, double *fracp); 

int
main(void)
{
      double value; /* input - number to analyze 	*/
      char   sn;    /* output - sign of value 	*/
      int    whl;   /* output - whole number magnitude of value 	*/
      double fr;    /* output - fractional part of value 	*/

      /* Gets data 	*/
      printf("Enter a value to analyze> ");
      scanf("%lf", &value);

      /* Separates data value into three parts 	*/
      separate(value, &sn, &whl, &fr);

      /* Prints results 	*/
      printf("Parts of %.4f\n  sign: %c\n", value, sn);
      printf("  whole number magnitude: %d\n", whl);
      printf("  fractional part:  %.4f\n", fr);

      return (0);
}

/*
 * Separates a number into three parts: a sign (+, -, or blank), 
 * a whole number magnitude, and a fractional part.
 * Pre:  num is defined; signp, wholep, and fracp contain addresses of memory 
 *       cells where results are to be stored
 * Post: function results are stored in cells pointed to by signp wholep, and 
 *       fracp
 */
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;  /* local variable - 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;
}


/*
Enter a value to analyze> 35.817
Parts of 35.8170
  sign: +
  whole number magnitude: 35
  fractional part: 0.8170
*/