$re = '/\s*Amount:\s*(\d+)/';
$str = 'Date:21
Month:03
Year:2017
Amount:50
Category:Wow
Account:The
Note:This';
preg_match_all($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