$re = '/Src\/High\/SS\/(?!FormCalc).+/';
$str = 'Src/High/SS/ATG_Help
Src/High/SS/ConvCalc
Src/High/SS/ConvX
Src/High/SS/EFiling
Src/High/SS/Edit
Src/High/SS/FormCalc
Src/High/SS/FormDisp
Src/High/SS/Image
Src/High/SS/Import
Src/High/SS/Importables
Src/High/SS/Intrview
Src/High/SS/Intrview/Dialog
Src/High/SS/Intrview/Dialog/Facades
Src/High/SS/Intrview/Dialog/Facades/PrivateHeaders
Src/High/SS/Intrview/Dialog/PrivateHeaders
Src/High/SS/Misc';
preg_match_all($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