$re = '/^(?!\s)(?=\w*[A-Z]\w*[A-Z])(?!\s)(?=\w*[a-z]\w*[a-z])(?=\w*[0-9]\w*[0-9])\w*$/';
$str = 'Password_Must_Have_2Cap_2Smal_2num_no_space';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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