$re = '/(?<=[\w ]\()[^;\n]*(?=\))/mx';
$str = 'foo(() ((hello) world))
bar (hello world!)
baz(ddd(()))
bazbaz(dsadsa")" dsada)
bazbaz(dsadsa")" d(()(das))das)das)ds)a(d(sa(d)()()sada); ;; d(ssss)
h(dsaqwd)
h(dsaqwd);h(dsaqwd)
h(dsaqwd); h(dsaqwd);
foo(() ((hello) world)); bar(gffjdk)';
preg_match_all($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