Get the final key of an array in PHP

Question

I have a standard associative array in PHP. what's the simplest way to get the last key in that array?

example:

$foo = array('key1' => 'val1', 'key2' => 'val2', 'key3' => 'val3');

and i would like to get 'key3';

Answer 1

$keys = array_keys($foo);
$last = end($keys);

you need to pass an actual variable to end, you can't put another function inside there.

Answer 2

Fastest method would be this:

end($foo);
$last = key($foo);

Tesserex's method is unnecessarily resource hungry when you don't need all keys.

Answer 3

The following is not the simplest, but it will may be much happier to deal with large (in terms of number of elements; though will probably^† be better for most uses) arrays than the other answers.

$last_key = key(array_slice($subject, -1, 1, true));

^{† educated guess, may not be true for all cases}