What's the difference between isset() and array_key_exists()? [duplicate]

Answer 1

The main difference when working on arrays is that array_key_exists returns true when the value is null, while isset will return false when the array value is set to null.

See isset on the PHP documentation site.

Answer 2

The two are not exactly the same. I couldn't remember the exact differences, but they are outlined very well in What's quicker and better to determine if an array key exists in PHP?.

The common consensus seems to be to use isset whenever possible, because it is a language construct and therefore faster. However, the differences should be outlined above.