PHP两个数组合并键值

$a = array('admin' => array('coures' => '1'), 'dept' => array('coures' => '2'), 'hsa' => array('coures' => '3'), 'user' => array('coures' => '4'));
$b = array('admin' => array('job' => '1'), 'hsa' => array('test' => '2'));
$c = array();
foreach ($a as $key => $val) {
    $c[$key] = $val;
    foreach ($b as $k => $v) {
        if ($key == $k) {
            foreach ($v as $x => $t) {
                $c[$key][$x] = $t;

            }
        }
    }

}

echo '<pre>';

print_r($c);

echo '</pre>';

echo '<hr/>';