PHP Function – Calculating Days In A Month

By  on  

All developers keep a tool box of useful functions and classes that they pick up or write along the way and this PHP came to me while I was writing an event calendar page for a customer.

I should mention that PHP does offer a cal_days_in_month function for PHP builds of PHP 4.0.7 and higher, but I prefer using the below function because it is guaranteed to work on all PHP version because it is based solely on logic.

The Code

function get_days_in_month($month, $year)
{
   return $month == 2 ? ($year % 4 ? 28 : ($year % 100 ? 29 : ($year %400 ? 28 : 29))) : (($month - 1) % 7 % 2 ? 30 : 31);
}

One line of logic provides the number of days in a month, taking into account leap years, and all on one line.

Recent Features

  • By
    9 Mind-Blowing WebGL Demos

    As much as developers now loathe Flash, we're still playing a bit of catch up to natively duplicate the animation capabilities that Adobe's old technology provided us.  Of course we have canvas, an awesome technology, one which I highlighted 9 mind-blowing demos.  Another technology available...

  • By
    9 Mind-Blowing Canvas Demos

    The <canvas> element has been a revelation for the visual experts among our ranks.  Canvas provides the means for incredible and efficient animations with the added bonus of no Flash; these developers can flash their awesome JavaScript skills instead.  Here are nine unbelievable canvas demos that...

Incredible Demos

  • By
    Web Audio API

    The Web Audio API allows developers to load and decode audio on demand using JavaScript.  The more I evaluate awesome games for Firefox OS TVs, the more I get to learn about these APIs that I normally wouldn't touch.  The following is a very basic introduction to the WebAudio API...

  • By
    Elegant Overflow with CSS Ellipsis

    Overflow with text is always a big issue, especially in a programmatic environment. There's always only so much space but variable content to add into that space. I was recently working on a table for displaying user information and noticed that longer strings were...

Discussion

  1. noseyparker

    Thanks for your very helpful site! Love the tips.

  2. Michael Quinn

    Hi David,

    PHP versions 4&5 also offer the date("t") function which returns number of days in given month.

  3. michael is right: $totDays = date("t",strtotime($year.'-'.$_month.'-01'));

  4. LOL.. Thanks Michael and Paskuale but I think you’re both missing the point! It’s nice to be told that we can get the days directly but the point about this function is that it’s an easily recognisable way to learn how ternary functions in PHP.

    Very useful for noobies such as myself – thanks David :)

  5. LOL.. Thanks Michael and Paskuale but I think you’

    LOL.. Thanks Michael and Paskuale but I think you’re both missing the point! It’s nice to be told that we can get the days directly but the point about this function is that it’s an easily recognisable way to learn how ternary functions in PHP.

    Very useful for noobies such as myself – thanks David :)

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