/*
 * The behavior of rolling a pair of dice.
 *
 * The total roll can be anywhere from 2 to. We want to count how often each
 * roll comes up. We use an array to keep track of the counts: a[2] will count
 * how many times we've rolled 2, etc.
 *
 * We simulate the roll of a die by calling C's random number generation
 * function, rand(). Each time rand() is called, it returns a different,
 * pseudo-random integer. The values that rand() returns typically span a large
 * range. We use C's modulus (or ``remainder'') operator % to produce random
 * numbers in the range we want. The expression rand() % 6 produces random
 * numbers in the range 0 to 5, and rand() % 6 + 1 produces random numbers in
 * the range 1 to 6.
 */

#include <stdio.h>
#include <stdlib.h>

main ()
{
  int i;
  int d1, d2;
  int a[13];			/* uses [2..12] */

  /* Initialize: */
  for (i = 2; i <= 12; i++)
    a[i] = 0;

  /* Compute: */
  for (i = 0; i < 1000; i++) {
    d1 = rand () % 6 + 1;
    d2 = rand () % 6 + 1;
    a[d1 + d2] = a[d1 + d2] + 1;
  }

  /* Print out: */
  for (i = 2; i <= 12; i++)
    printf ("%2d: %3d\n", i, a[i]);

  return 0;
}