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
    How to Create a RetroPie on Raspberry Pi – Graphical Guide

    Today we get to play amazing games on our super powered game consoles, PCs, VR headsets, and even mobile devices.  While I enjoy playing new games these days, I do long for the retro gaming systems I had when I was a kid: the original Nintendo...

  • By
    Serving Fonts from CDN

    For maximum performance, we all know we must put our assets on CDN (another domain).  Along with those assets are custom web fonts.  Unfortunately custom web fonts via CDN (or any cross-domain font request) don't work in Firefox or Internet Explorer (correctly so, by spec) though...

Incredible Demos

  • By
    Create Spinning, Fading Icons with CSS3 and MooTools

    A goal of my latest blog redesign was to practice what I preached a bit more;  add a bit more subtle flair.  One of the ways I accomplished that was by using CSS3 animations to change the display of my profile icons (RSS, GitHub, etc.)  I...

  • By
    MooTools ASCII Art

    I didn't realize that I truly was a nerd until I could admit to myself that ASCII art was better than the pieces Picasso, Monet, or Van Gogh could create.  ASCII art is unmatched in its beauty, simplicity, and ... OK, well, I'm being ridiculous;  ASCII...

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!