$re = '/(((([0-9]*\.[0-9]+)|([0-9]+\.[0-9]*))(E(\+|-)?[0-9]+)?)|([0-9]+(?6)))$/m';
$str = '12123123E12
# Parts
(
(
([0-9]*\\.[0-9]+) |
([0-9]+\\.[0-9]*)
)
(E(\\+|-)?[0-9]+)?)
) |
([0-9]+(?6)
)
';
preg_match($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