# michaeldperez's solution

## to Leap in the PHP Track

Published at Sep 09 2019 · 0 comments
Instructions
Test suite
Solution

Given a year, report if it is a leap year.

The tricky thing here is that a leap year in the Gregorian calendar occurs:

``````on every year that is evenly divisible by 4
except every year that is evenly divisible by 100
unless the year is also evenly divisible by 400
``````

For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap year, but 2000 is.

If your language provides a method in the standard library that does this look-up, pretend it doesn't exist and implement it yourself.

## Notes

Though our exercise adopts some very simple rules, there is more to learn!

For a delightful, four minute explanation of the whole leap year phenomenon, go watch this youtube video.

## Running the tests

1. Go to the root of your PHP exercise directory, which is `<EXERCISM_WORKSPACE>/php`. To find the Exercism workspace run

`````` % exercism debug | grep Workspace
``````
2. Get PHPUnit if you don't have it already.

`````` % wget --no-check-certificate https://phar.phpunit.de/phpunit.phar
% chmod +x phpunit.phar
``````
3. Execute the tests:

`````` % ./phpunit.phar leap/leap_test.php
``````

## Source

JavaRanch Cattle Drive, exercise 3 http://www.javaranch.com/leap.jsp

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### leap_test.php

``````<?php

class YearTest extends PHPUnit\Framework\TestCase
{
public static function setUpBeforeClass() : void
{
require_once 'leap.php';
}

public function testLeapYear() : void
{
\$this->assertTrue(isLeap(1996));
}

public function testNonLeapYear() : void
{
\$this->assertFalse(isLeap(1997));
}

public function testNonLeapEvenYear() : void
{
\$this->assertFalse(isLeap(1998));
}

public function testCentury() : void
{
\$this->assertFalse(isLeap(1900));
}

public function testFourthCentury() : void
{
\$this->assertTrue(isLeap(2400));
}
}``````
``````<?php

function isLeap(int \$year) : bool
{
\$divisibleBy4      = isDivisibleBy(4)(\$year);
\$notDivisibleBy100 = !isDivisibleBy(100)(\$year);
\$divisibleBy400    = isDivisibleBy(400)(\$year);

return \$divisibleBy4 && (\$notDivisibleBy100 || \$divisibleBy400);
}

function isDivisibleBy(int \$divisor) : callable
{
return function(int \$dividend) use (\$divisor) : bool
{
return \$dividend % \$divisor == 0;
};
}``````