C program to check leap year

/*A leap year (also known as an intercalary year or a bissextile year) is a year containing one additional day (or, in the case of lunisolar calendars, a month) added to keep thecalendar year synchronized with the astronomical or seasonal year.[1] Because seasons and astronomical events do not repeat in a whole number of days, calendars that have the same number of days in each year, drift over time with respect to the event that the year is supposed to track. By inserting (also called intercalating) an additional day or month into the year, the drift can be corrected. A year that is not a leap year is called a common year.

For example, in the Gregorian calendar, each leap year has 366 days instead of the usual 365, by extending February to 29 days rather than the common 28.



Algorithm

if (year is not exactly divisible by 4) then (it is a common year)
else if (year is not exactly divisible by 100) then (it is a leap year)
else if (year is not exactly divisible by 400) then (it is a common year)
else (it is a leap year) */

Program

#include <stdio.h>
void main()
{
  int year;
  printf("Enter a year to check if it is a leap year\n");
  scanf("%d", &year);

  if ( year%400 == 0)
  printf("%d is a leap year.\n", year);
  else if ( year%100 == 0)
  printf("%d is not a leap year.\n", year);
  else if ( year%4 == 0 )
  printf("%d is a leap year.\n", year);
  else
  printf("%d is not a leap year.\n", year);
}

Output

Enter a year to check if it is a leap year
2012
2012 is a leap year.