C Program to Check Leap Year

A leap year is a calendar year in which an additional day is added to February month. In a leap year, the number of days in February month and the year are 29 and 366 respectively. A year that is not a leap year is called a common year. A year is said to be a leap year if

• it is divisible by 4.
• it is divisible by 4 but not divisible by 100.
• it is divisible by 4, 100 and 400.

Method 1: Using conditional statements

In the example below, conditional statements are used to identify a leap year.

#include <stdio.h>

int main() {
  int year = 2019;
  if (year % 400 == 0) {
     printf("%i is a leap year.", year);
  } else if (year % 100 == 0) {
     printf("%i is not a leap year.", year);
  } else if (year % 4 == 0) {
     printf("%i is a leap year.", year);
  } else {
     printf("%i is not a leap year.", year);
  }
}

The above code will give the following output:

2019 is not a leap year.

Method 2: Using function

In the example below, a function called leapyear() is created which takes year as argument and prints whether the passed year is a leap year or not.

#include <stdio.h>

static void leapyear(int);

static void leapyear(int year) {
  if (year % 400 == 0) {
     printf("%i is a leap year.", year);
  } else if (year % 100 == 0) {
     printf("%i is not a leap year.", year);
  } else if (year % 4 == 0) {
     printf("%i is a leap year.", year);
  } else {
     printf("%i is not a leap year.", year);
  }
}
int main() {
  leapyear(2019);
}

The above code will give the following output:

2019 is not a leap year.