PHP: high depth array, how do return current key name?

[barrasadrugstore]

I have a huge array from a json_decode result (assoc set to true) and have the following code to check if (one of the arrays within, a random serial) has the key 'set_true'\[code\]$out = "";foreach ($array as $sub) { //$out[] = $sub['set_true']; if (in_array($sub['set_true'], $sub) && $sub['set_true'] == '1' ) { $out[] = 'User: ' . $sub . ' has set_true = 1'; }}\[/code\]That code lists all the users with that array key set to 1, but $sub returns 'array' and not the current key I'm on! (the random serial)How do I return it?