PHP/REGEX: Get a string within parentheses

try:

preg_match('/\((.*?)\)/', $s, $a);

output:

Array
(
    [0] => (hollow highlight)
    [1] => hollow highlight
)

You just need to add capturing parenthesis, in addition to your escaped parenthesis.

<?php
    $in = "hello (world), my name (is andrew) and my number is (845) 235-0184";
    preg_match_all('/\(([A-Za-z0-9 ]+?)\)/', $in, $out);
    print_r($out[1]);
?>

This outputs:

Array ( [0] => world [1] => is andrew [2] => 845 )