Getting last numeric index in PHP array

Question

I have a PHP array that has both a varying number of elements and varying types of associations, like so:

$example =
Array
(
    [0] => 12345
    [1] => 100
    [2] => Some String

    ...

    [17] => 2
    [18] => 0
    [type] => Some String
    [inst] => Array
        (
            [0] => Some String
        )
    [method] => Some String

)

$other = 
Array
(
    [0] => 45678
    [1] => 250
    [2] => Some String

    ...

    [8] => 7
    [9] => -2
    [inst] => Array
        (
            [0] => Some String
            [1] => Some String
        )

)

What I'm trying to do is get the last numerical index in these arrays and some before it. Like, in the first example, I want to get $example[18] and in the second I want to return $other[9].

I was using count($array)-1 before the named associations came into play.

Community · Accepted Answer · 2023-11-17 20:42:18Z

5

Use max and array_keys

echo max(array_keys($array));

In case of a possibility of alphanumeric keys, you can use

~~echo intval(max(array_keys($array)));~~

echo max(array_filter(array_keys($array), 'is_int'));  
// hint taken from Amal's answer, but index calculation logic is still same as it was.

Demo

edited Nov 17, 2023 at 20:42

CommunityBot

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answered Nov 17, 2013 at 5:23

Hanky Panky

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12 Comments

JaidynReiman Over a year ago

Max evaluates strings as 0. Interesting, didn't know that. That's helpful. I figured an option was to use array_keys. +1

Hanky Panky Over a year ago

Yep, max: When given a string it will be cast as an integer when comparing.

Déjà vu Over a year ago

What if the array contains ("19xyz" => "value")?

JaidynReiman Over a year ago

The number at the beginning is taken into consideration; xyz is ignored. "19xyz" would evaluate as "19." If you have numbers at the beginning of a string and don't want it to return those, then just using max won't work for you.

Amal Over a year ago

This would fail if the array keys aren't ordered. @Corey: you should make it clear whether you need exactly the last numeric key's value or the greatest numeric key's value.

|

Amal · Accepted Answer · 2013-11-17 05:31:01Z

5

If your array isn't ordered and you want to get the last numeric index, then you could use array_filter() as follows:

$numerickeys = array_filter(array_keys($example), 'is_int');
echo end($numerickeys); // => 18

Demo!

answered Nov 17, 2013 at 5:31

Amal

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Comments

Paulo Freitas · Accepted Answer · 2013-11-17 05:32:14Z

1

This one will always work as expected:

var_dump(max(array_filter(array_keys($example), 'is_int'))); # int(18)
var_dump(max(array_filter(array_keys($other), 'is_int'))); # int(9)

answered Nov 17, 2013 at 5:32

Paulo Freitas

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