Checking For Leap Year Using PHP

By  on  

One part of programming that seems pretty static is dealing with dates. The calendar is a set system of rules that doesn't look to change. The only part of the calendar that can be variable is a leap year, which changes every four years (obviously).

Using pure PHP ternary logic, much like the PHP Function - Calculating Days In A Month, I posted a few weeks back, you can check to see if a year is a leap year.

The Code

function is_leap_year($year) {
	return ((($year % 4) == 0) && ((($year % 100) != 0) || (($year % 400) == 0)));
}

Recent Features

Incredible Demos

  • By
    Instagram For MooTools

    If you're still rocking an iPhone and fancy taking a photo every now and then, you'd be crazy not to be using an app called Instagram.  With Instagram you take the photos just as you would with your native iPhone camera app, but Instagram...

  • By
    Create a Download Package Using MooTools Moousture

    Zohaib Sibt-e-Hassan recently released a great mouse gestures library for MooTools called Moousture. Moousture allows you to trigger functionality by moving your mouse in specified custom patterns. Too illustrate Moousture's value, I've created an image download builder using Mooustures and PHP. The XHTML We provide...

Discussion

  1. Placing a function call as an argument default will result in a fatal error. Also, give this version a shot:

    function is_leap_year( $year = NULL )
    {
        if_numeric( $year ) || $year = date( 'Y' );
        return checkdate( 2, 29, ( int ) $year );
    }
  2. Whoops, small typo… if_numeric( $year ) should be is_numeric( $year )… :x

  3. Tamlyn

    Better yet, use date('L') which returns 1 if it’s a leap year, 0 if it isn’t.

  4. I do agree with tamlyn, why you dont use date function??
    It can makes a load fasting right?

  5. Travis

    date(‘L’) is way better because leap year is not every 4 years.

  6. Date("L") only tell you in a given year, default is the year today.
    If you need to know whether previous or next year is a leap, you must reset the date.
    It could affect the system.

    • Indra, you can always pass the timestamp as second parameter to date function:

      echo date('L', mktime(1, 1, 1, 1, 1, 2005));
      
  7. I think this is a better example relating to the function. Also provided example for anyone looking for true/false as I was in this instance.

    /* for true or false */
    function is_leap_year($year)
    {
    	return ( date ('L', mktime(1,1,1,1,1, $year) ) === 1 ) ? true : false;
    }
    /*for 0 or 1 Whether it's a leap year: 1 if it is a leap year, 0 otherwise. */
    function is_leap_year($year)
    {
    	return date ('L', mktime(1,1,1,1,1, $year) );		
    }
    
  8. Habibur Rahaman
    <?php
    $day = "";
    for($i=0; $i<4; $i++)
    {
        $day =  date("d", mktime(0, 0, 0, 2, 29, date("Y")+$i));
        if($day == 29)
        {
            $year = date("Y")+$i;
            break;
        }
    }
    echo "The next leap year is 29th February $year";    
    ?>
    
    
  9. Milan Dvořák

    code of Habibur Rahaman will not work for example for the year 1897, because 1900 is not leap year.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!