Recently, an obscure detail in the way PHP processes strings came to my attention in the form of an endless loop occasionally found in phpDocumentor's parsing of a file.

This is processed by code that checks for simple lists (like 1. blah 2. blah, or - blah - blah, etc.). However, an innocent call to in_array($x, array('1.', '0.')) had surprising and unexpected results: our friendly PHP determined that '01' was in the array('1.', '0.')!! This is of course patently false, and made little to no sense until I realized that unlike my previous understanding (when comparing an integer to a string, the string is converted to an integer), PHP actually converts all numeric-like strings into integers when comparing them.

To help avoid these kinds of situations repeating themselves, he makes a few suggestions when comparing your values: "use === instead of ==", "use the third parameter in in_array, set to true", and "use strcmp() or one of its cousins". In his opinion, though, this kind of auto-conversion is a bit dangerous - bit it's all about perspective...]]> Fri, 16 Dec 2005 07:11:30 -0600