/*
 * Adds fractions represented by pairs of integers.
 */

#include <stdlib.h>    /* provide function abs */ 

void
add_fractions(int n1, int d1, int n2, int d2, int *n_ansp, int *d_ansp) 
{
      int denom, numer,  sign_factor; 

      /* Finds a common denominator	*/
      denom = d1 * d2;

      /* Computes numerator	*/
      numer = n1 * d2 + n2 * d1;

      /* Adjusts sign (at most, numerator should be negative)	*/
      if (numer * denom >= 0)
          sign_factor = 1;
      else
          sign_factor = -1;

      numer = sign_factor * abs(numer);
      denom = abs(denom);

      *n_ansp = numer;
      *d_ansp = denom;
}