How to know the last index of an disorder array

Question

I have an array like this:

Array ( [2] => -100 [0] => -7.1 )

It is not ordered because if I sort this array, it will become this array into this Array ( [0] => -7.1 [1] => -100) and I am not looking for that, I just want to know the index value of an array like that....

In this case if I use the php function to know the last index it shows me 0 BUT althought it's in the last position the last index really is 2, how can I get 2 and not 0?

I am not using PHP 7, I am using PHP 5

Thanks

Does this answer your question? [Search for highest key/index in an array](https://stackoverflow.com/questions/6126066/search-for-highest-key-index-in-an-array) — Kaz, Mar 02 '20 at 05:35

Theder · Answer 1 · 2020-03-02T00:25:36.823

1

There is the function array_key_last(). It's return the last key of an array. Here is an example (PHP 7+):

// array_key_last()  ( array $array ) : mixed

$arr = [
    '2' => 3,
    '5' => 2,
    '0' => 10
];

print_r(array_key_last($arr));

UPDATE

In PHP 7 there is no array_key_last() function, so in PHP 5 we can use end() with key(). Function end() set the pointer of array to the last element and return it. Function key() return the key of the current element of array. Example:

$arr = [
    '2' => 3,
    '5' => 2,
    '0' => 10
];

end($arr);
print_r(key($arr));

edited Mar 02 '20 at 00:25

answered Mar 02 '20 at 00:10

Theder

59
4

I am not using PHP 7 so it does not work to me – Jesús Cova Mar 02 '20 at 00:10
@JesúsCova update for PHP 5 – Theder Mar 02 '20 at 00:26
Upvoted your answer. – Jonathan Rosa Mar 02 '20 at 00:28
It would not work, because end() will display the index 0 as last one, and it's not correct I already tried it – Jesús Cova Mar 02 '20 at 00:30

score 1 · Accepted Answer · answered Mar 02 '20 at 00:29

1

Since there is no regularity in your proposed array structure, use max(array_keys($arr)).

answered Mar 02 '20 at 00:29

El_Vanja

3,660
4
18
21

score 0 · Answer 3 · answered Mar 02 '20 at 00:21

0

Since you are not using PHP7, you can use count minus 1

$a = array(5, 3, 4);
print_r($a[count($a) - 1]);

answered Mar 02 '20 at 00:21

Jonathan Rosa

992
7
22

This is incorrect for OP's example. His max index is 2, even though the array only contains two elements. Meaning there's risk of an undefined index error. – El_Vanja Mar 02 '20 at 00:26
Those details weren't there when he first posted it. – Jonathan Rosa Mar 02 '20 at 00:27
@El_Vanja I know that it is one undefined index, for that reason I said an array like that – Jesús Cova Mar 02 '20 at 00:30
Yes, I understood that, I was just explaining why this solution wouldn't work. – El_Vanja Mar 02 '20 at 00:32

How to know the last index of an disorder array

3 Answers3