break; case ']': $complement = '['; break; case '}': $complement = '{'; break; } return $complement; } $test = new Tests('Brackets'); // example1 // example test 1 $A = '{[()()]}'; $result = 1; $test->run($A, $result); // example2 // example test 2 $A = '([)()]'; $result = 0; $test->run($A, $result); // negative_match // invalid structures $A = '{{{{'; $result = 0; $test->run($A, $result); // empty // empty string $A = ''; $result = 0; $test->run($A, $result);