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

#include <iostream>
using namespace std;

int main() {
  int year = 2019;
  if (year % 400 == 0) {
     cout<<year<<" is a leap year.";
  } else if (year % 100 == 0) {
     cout<<year<<" is not a leap year.";
  } else if (year % 4 == 0) {
     cout<<year<<" is a leap year.";
  } else {
     cout<<year<<" is not a leap year.";
  }
  return 0;
}

The above code will give the following output:

2019 is not a leap year.

Method 2: Using function

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

#include <iostream>
using namespace std;

static void leapyear(int);

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

The above code will give the following output:

2019 is not a leap year.