Online PHP editor | refs for J1eMO

<?php function camelCaseToUnderscore($input) { return strtolower(preg_replace('/(?<!^)[A-Z]/', '_$0', $input)); } echo camelCaseToUnderscore('CamelCaseForTheWin'), "\n"; echo camelCaseToUnderscore('ACar'), "\n"; echo camelCaseToUnderscore('BuyACar'), "\n"; echo camelCaseToUnderscore('XML'), "\n"; echo camelCaseToUnderscore('SimpleXML'), "\n";