Hi, phristen,
  you request can be easily satisfied by using:

$array = array(1, 2, 3);

reset($array); // point to the first element
echo key($array); // the first key: 0
echo current($array); // first value

end($array); // now point to the last values
echo key($array); // last key
echo current($array); // last value

please refer to : http://www.php.net/manual/en/function.reset.php
----------------------

BTW: if you want to get all of keys of an array,
you could use array_keys()  but not key() :)

Thanks.

But from my point view, I'd like those functions. It really makes
code more easy to read.

This is a very basic operation, and it should be done in a single function call.
I know about reset(), and I think it's ridiculous to have to call it every time I need to get the last element. It's also easy to 'forget' to reset it, and mess up your arrays.
And it's gonna turn into a terrible mess when you have to use first and last in a single statement (e.g. comparing first to last inside an if())

P.S.
I just used key() in my example to demonstrate that array_last should not change the internal pointer.

> Also consider implementing another pair of function to retrieve the keys: array_first_key and array_last_key.

These two functions were implemented via https://wiki.php.net/rfc/array_key_first_last in PHP 7.3

Indeed, array_key_first() and array_key_last() are available as of
PHP 7.3.0.  array_value_first() and array_value_last() have been
explicitly rejected, since the easily can be implemented in
userland (or used inline).