PHP

Official reference: https://www.php.net/

When you state a verified signature, return behavior, or version fact, name the php.net page you verified against — the specific function page (e.g. https://www.php.net/manual/en/function.strpos.php), not a generic "see php.net". When you answered from stable, well-known syntax with no lookup, say so explicitly ("no lookup needed — core syntax") instead of hedging on everything.

When to check php.net

PHP has a large, inconsistent standard library (argument order, return types, and null/false edge cases vary function to function, and behavior has shifted across major versions). Don't guess on these — look them up: