--TEST--
Study regex
--FILE--
<?php
var_dump(preg_match('/(?:(?:(?:(?:(?:(.))))))/ S', 'aeiou', $dump));
var_dump($dump[1]);
var_dump(preg_match('/(?:(?:(?:(?:(?:(.))))))/', 'aeiou', $dump));
var_dump($dump[1]);
var_dump(preg_match('/(?>..)((?:(?>.)|.|.|.|u))/S', 'aeiou', $dump));
var_dump($dump[1]);
var_dump(preg_match('/^aeiou$/S', 'aeiou', $dump));
var_dump($dump[0]);
var_dump(preg_match('/aeiou/S', 'aeiou', $dump));
var_dump($dump[0]);
?>
--EXPECT--
int(1)
string(1) "a"
int(1)
string(1) "a"
int(1)
string(1) "i"
int(1)
string(5) "aeiou"
int(1)
string(5) "aeiou"