$re = '/^([+-])?\d+(?:\.\d+)?(?(1)%)?$/m';
$str = '+10%
+10.0
-123
-123.5
+50
+50.9
99
99.1
-20%
-20.3%
25%
25.8%';
preg_match_all($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