/*
 * Converts year of century (since 1900) to date.
 */

#include <stdio.h>

void main()
{
   long int century_days;
   int four_year_sets, jul_date, year_quo, year, month, day, year_mod,
   mo_ent[12] = {
      31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31   };

   do {
      printf("Enter day of century -> ");
      fflush(stdout);
      scanf("%ld", &century_days);

      if (century_days < 0)
         printf("Positive values only \a\n");
   } while (century_days < 0);

   four_year_sets = century_days / 1461; /*No days in 4 years*/
   year_mod = century_days % 1461;

   switch (year_mod) {
   case 1154 : 
      {    /*Leap year day*/
         month = 2;
         day = 29;
         year = 1904 + 4 * four_year_sets;
         break;
      }
   case 1460 : 
      { /*Dec 31 of a leap year*/
         month = 12;
         day = 31;
         year = 1904 + 4 * four_year_sets;
         break;
      }
   default: 
      {
         year_quo = year_mod / 365;
         jul_date = year_mod % 365;
         year = 1901 + 4 * four_year_sets + year_quo;
         if (year_mod < 1154)
            jul_date++;
         for (month=1; jul_date > mo_ent[month - 1]; month++)
            jul_date -= mo_ent[month - 1];
         day = jul_date;
      }
   }    /* End of switch */

   printf("Day %ld is the date %d/%d/%d\n", century_days, month, day,
       year);
}