PHP's Quirks Under the Spotlight: Falsy Strings, Array Key Collisions, and Reference Pitfalls

A developer revisits PHP, one of the web's longest-running and most criticized languages, to highlight surprising behaviors in ordinary code. The article notes that PHP treats the string "0" and empty strings as falsy while "00" and "false" are truthy, which can wrongly reject valid input. It also explains that PHP array keys undergo implicit type conversion, so keys like "8" and 8 collide and integer, string, and boolean keys can overwrite each other. Finally, it describes how a foreach loop that iterates by reference can leave a lingering reference that corrupts array values in a later loop, a documented behavior the fix for which is to unset the reference.