$re = '/\( # Match (
( # Capture in group 1:
[^()]* # Any number of characters except ()s
) # End of group 1
\) # Match )
\{([^{}]*)\} # The same for {...} into group 2
\[([^\[\]]*)\] # The same for [...] into group 3/x';
$str = '<%(ddlValue){DropDownList}[SelectedValue]%>';
preg_match($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