/* Pass by reference */

#include <stdio.h>

void swap(int *x, int *y);

void main(void) {

  int number_1 = 5;
  int number_2 = 10;

  printf("Initially:\n number_1: %i \t number_2: %i\n", number_1, number_2);

  swap(&number_1, &number_2);

  printf("Swapped:\n number_1: %i \t number_2: %i\n", number_1, number_2);
}

void swap(int *x, int *y) {

  int hold;

  hold = *x;

  *x = *y;
  
  *y = hold;
}

/* OUTPUT
 *
 * Initially:
 *  number_1: 5     number_2: 10
 * Swapped:
 *  number_1: 10    number_2: 5
 *
 */