How to get last key in an array?

The recommended way to get the last key of an array in PHP (7.3+) is using the array_key_last() function. For example:

How to get the last key of an array in PHP?

<?php

$array = [1, 2, 3, 4, 5];
$last_key = array_key_last($array);
echo $last_key; // Outputs 4

<div class="alert alert-info flex not-prose"> <span class="hidden md:block">Watch a video course </span> Learn object oriented PHP</div>

Alternatively, you can use the end() function combined with key() to get the last key. Note that end() modifies the internal pointer of the array. For example:

How to get the last key of an array in PHP using end() and key()?

<?php

$array = [1, 2, 3, 4, 5];
end($array);
$last_key = key($array);
echo $last_key; // Outputs 4

If you need to preserve the state of the array after using end(), you can reset the pointer:

How to get the last key of an array in PHP while preserving the array state?

<?php

$array = [1, 2, 3, 4, 5];
end($array);
$last_key = key($array);
reset($array);

print_r($array);

You can also use the count() function to calculate the last index, but this only works for sequential numeric arrays. For associative arrays, it will produce incorrect results. For example:

How to get the last key of an array in PHP using count() function?

<?php

$array = [1, 2, 3, 4, 5];
$last_key = count($array) - 1;
echo $last_key; // Outputs 4