$re = '/(^[tT][0-9]+[_])(.*)(submit$)/m';
$str = '
t1_click
t123_click_submit
T12_click_click_submit
t12_click_click_skip
t1234_click_click_click_skip
t12_clcik_sdsdssd
t1234_click_xyz
T12_click
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php