A **leap year** is a year that has 29 days in the month of February. This is done to keep the calendar year the same as the astronomical year because astronomical years have a quarter of a day more than the calendar year. This is why a leap year occurs once every 4 years.

To see if a given year is a leap year, use the algorithm below:

> **If** (*year* is not **divisible** by 4) **then** (it is a *common* year)<br/>
**else if** (year is not divisible by 100) **then** (it is a *leap* year)<br/>
**else if** (year is not divisible by 400) **then** (it is a common year)<br/>
**else** (it is a leap year)

# Code

#include <iostream>
using namespace std;

int main() {
  int year = 2020;

  if (year % 4 != 0)
    cout << year << " is a common year.";
  else if (year % 100 != 0)
    cout << year << " is a leap year.";
  else if (year % 400 != 0)
    cout << year << " is a common year.";
  else
    cout << year << " is a leap year.";
}

How to check if a year is a leap year

Code