This function checks if every character of the string given is a lowercase character. “Lowercase” is defined by the locale as it is set at the time of calling. Be sure to see the introduction to ctype functions.

Keep in mind that every character is looked at. Even whitespace will result in FALSE.

$res = ctype_lower( 'monkey' );     // true
$res = ctype_lower( 'Monkey' );     // false
$res = ctype_lower( 'look_at_me' ); // false
$res = ctype_lower( 'hi there' );   // false