## Check whether a year is a leap year

The following function checks whether a given year is a leap year.

```
```

<?php

function is_leap_year($year) {

return $year%4==0 && ($year%100!=0 || $year%400==0);

}

?>

### Explanation

Per definition, a year is leap year if it can be divided by 4, but not by 100
except it can be divided by 400.

In short: Every 4 years, except centuries, but every 4th century.

So the year 2000 was a leap year for example, because it can be divided by
4, (100) and 400.