What's quicker and better to determine if an array key exists in PHP?

Consider these 2 examples... $key = 'jim'; // example 1 if (isset($array[$key])) { // ... } // example 2 if (array_key_exists($key, $array)) { // ... } I'm interested in knowing if either of these are better. I've always used the first, but have seen a lot of people use the second example on this site. So, which is better? Faster? Clearer intent? [1]: http://codepad.org/RcdAewVF [2]: http://codepad.org/5qyvS93x