'1', ], Arrays::grep(['a', '1', 'c'], '#\d#')); Assert::same([ 0 => 'a', 2 => 'c', ], Arrays::grep(['a', '1', 'c'], '#\d#', PREG_GREP_INVERT)); Assert::same([ 0 => 'a', 2 => 'c', ], Arrays::grep(['a', '1', 'c'], '#\d#', invert: true));