$re = '/#Section(\d+)(?:(?!#Section\d).)*\bJack/M,\d+\h+(\d+(?:\.\d+)?)\b/m';
$str = '#Section250342,Main,First/HS/12345/Jack/M,2000 10.00,#Section250322,Main,First/HS/12345/Aaron/N,2000 17.00,#Section250399,Main,First/HS/12345/Jimmy/N,2000 12.00,#Section251234,Main,First/HS/12345/Jack/M,2000 11.00';
preg_match_all($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