CODEWITHSUNDEEP
phparraysunset
Oliver Spryn
Oliver Spryn

Reputation: 17348

PHP Unset Array value effect on other indexes

I am working with a PHP loop, and I had one question regarding how unset affects the array keys. This array uses the standard numeric keys assigned by PHP, 0, 1, 2, 3 etc.... Whenever unset() runs on an array value, are the array keys shuffled or are they maintained as before?

Thank you for your time.

Upvotes: 23

Views: 109817

Answers (6)

Amr Berag
Amr Berag

Reputation: 1110

The keys are maintained with the removed key missing but they can be rearranged by doing this:

$array = array(1,2,3,4,5);
unset($array[2]);
$arranged = array_values($array);
print_r($arranged);

Outputs:

Array
(
    [0] => 1
    [1] => 2
    [2] => 4
    [3] => 5
)

Notice that if we do the following without rearranging:

unset($array[2]);
$array[]=3;

The index of the value 3 will be 5 because it will be pushed to the end of the array and will not try to check or replace missing index. This is important to remember when using FOR LOOP with index access.

Upvotes: 0

David Lartey
David Lartey

Reputation: 587

This might be a little bit out of context but in unsetting values from a global array, apply the answer by Michael Berkowski above but in use with $GLOBALS instead of the the global value you declared with global $variable_name. So it will be something like:

unset($GLOBALS['variable_name']['array_key']);

Instead of:

global $variable_name; unset($variable_name['array_key']);

NB: This works only if you're using global variables.

Upvotes: 1

Michael Berkowski
Michael Berkowski

Reputation: 270607

The keys are not shuffled or renumbered. The unset() key is simply removed and the others remain.

$a = array(1,2,3,4,5);
unset($a[2]);
print_r($a);

Array
(
    [0] => 1
    [1] => 2
    [3] => 4
    [4] => 5
)

Upvotes: 45

Jeff Lambert
Jeff Lambert

Reputation: 24661

The Key Disappears, whether it is numeric or not. Try out the test script below.

<?php
    $t = array( 'a', 'b', 'c', 'd' );
    foreach($t as $k => $v)
        echo($k . ": " . $v . "<br/>");
    // Output: 0: a, 1: b, 2: c, 3: d

    unset($t[1]);

    foreach($t as $k => $v)
        echo($k . ": " . $v . "<br/>");
    // Output: 0: a, 2: c, 3: d
?>

Upvotes: 2

Glen Solsberry
Glen Solsberry

Reputation: 12320

Test it yourself, but here's the output.

php -r '$a=array("a","b","c"); print_r($a); unset($a[1]); print_r($a);'
Array
(
    [0] => a
    [1] => b
    [2] => c
)
Array
(
    [0] => a
    [2] => c
)

Upvotes: 3

genesis
genesis

Reputation: 50976

They are as they were. That one key is JUST DELETED

Upvotes: 2

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