program13-1.c

// Program to print the number of days in a month

#include <stdio.h>

int main(void)
{
    enum month { January = 1, February, March,
      April, May, June, July, August, September,
      October, November, December};

    enum month aMonth;
    int days;

  printf("Enter month number: ");
  scanf("%i", &aMonth);

  switch (aMonth) {
      case January:
      case March:
      case May:
      case July:
      case August:
      case October:
      case December:
          days = 31;
          break;
      case April:
      case June:
      case September:
      case November:
          days = 30;
          break;
      case February:
          days = 28;
          break;
      default:
          printf("bad month number\n");
          days = 0;
          break;
  }

  if (days != 0)
      printf("Number of days is %i\n", days);

  if (aMonth == February)
      printf("...or 29 if it's a leap year\n");

  return 0;
}