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

Incredible Demos

  • By
    Duplicate the jQuery Homepage Tooltips

    The jQuery homepage has a pretty suave tooltip-like effect as seen below: The amount of jQuery required to duplicate this effect is next to nothing;  in fact, there's more CSS than there is jQuery code!  Let's explore how we can duplicate jQuery's tooltip effect. The HTML The overall...

  • By
    MooTools Font-Size Scroller with Cookie Save

    Providing users as many preferences as possible always puts a smile on the user's face. One of those important preferences is font size. I can see fine but the next guy may have difficulty with the font size I choose. That's why...

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!