strtolower Make a string lowercase stringstrtolower stringstr Returns string with all alphabetic characters converted to lowercase. Note that 'alphabetic' is determined by the current locale. This means that in i.e. the default "C" locale, characters such as umlaut-A (Ä) will not be converted. ]]> ¬e.bin-safe; See also strtoupper, ucfirst, ucwords and mb_strtolower.