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
    Create Namespaced Classes with MooTools

    MooTools has always gotten a bit of grief for not inherently using and standardizing namespaced-based JavaScript classes like the Dojo Toolkit does.  Many developers create their classes as globals which is generally frowned up.  I mostly disagree with that stance, but each to their own.  In any event...

  • 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...

Incredible Demos

  • By
    Add Styles to Console Statements

    I was recently checking out Google Plus because they implement some awesome effects.  I opened the console and same the following message: WARNING! Using this console may allow attackers to impersonate you and steal your information using an attack called Self-XSS. Do not enter or paste code that you...

  • By
    Dynamic Waveform Visualizations with wavesurfer.js

    Waveform images are an awesome addition to boring audio widgets.  They can be functional as well as aesthetically pleasing, allowing users to navigate audio visually.  I recently found wavesurfer.js, an amazing waveform image utility that uses to Web Audio API to create super customizable...

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!