$re = '/^([\s\S]*?\/)(\w+\.c)/m';
$str = 'a/b/c/d/file1.c
a/b/c/d/e/f/g/h/1/2/3/4/5/foo.c
dir1/dir2/newlinedir
/nextlinedir/bar.c';
preg_match_all($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