PHP Bugs Me, or Where Type Coercion Causes Bugs

I really like PHP as a technology, both for its extensibility and its deployment style. I think it is the quickest and most straightforward platform to create web applications with, and frameworks like CodeIgniter make it even better.

I’ve long been on the fence regarding PHP’s type coercion and comparison issues, but a recent bug in Mantis Bug Tracker has made me /facepalm for the first time in my long history of working with PHP:

When I click on “Edit” next to 1.2, mantis shows me the 1.20 properties. When I click 1.1 it shows me 1.10!

The offending snippet of code:

foreach( $g_cache_versions as $t_version ) {
   if ( ( $t_version['version'] == $p_version )
      && ( $t_version['project_id'] == $c_project_id ) ) {
      return $t_version['id'];

At first glance, it seems perfectly normal… and then you read the commit log, emphasis mine:

This is due to an incorrect version name comparison in version_get_id whereby the following check between strings was occurring:

if( "1.1" == "1.10" ) { ... }

PHP evaluates this expression to true because 1.1 and 1.10 are treated as floats. We however need to preserve the string type during this comparison, thus we need to use the === comparison operator instead.

I thought I’d seen it all…