Deleting an element from an array in PHP


Question

Is there an easy way to delete an element from an array using PHP, such that foreach ($array) no longer includes that element?

I thought that setting it to null would do it, but apparently it does not work.

1
2304
7/30/2019 4:29:09 AM

Accepted Answer

There are different ways to delete an array element, where some are more useful for some specific tasks than others.

Delete one array element

If you want to delete just one array element you can use \unset() or alternatively \array_splice().

Also if you have the value and don't know the key to delete the element you can use \array_search() to get the key.

\unset() method

Note that when you use \unset() the array keys won't change/reindex. If you want to reindex the keys you can use \array_values() after \unset() which will convert all keys to numerical enumerated keys starting from 0.

Code

<?php

    $array = [0 => "a", 1 => "b", 2 => "c"];
    \unset($array[1]);
                //↑ Key which you want to delete

?>

Output

[
    [0] => a
    [2] => c
]

\array_splice() method

If you use \array_splice() the keys will be automatically reindexed, but the associative keys won't change as opposed to \array_values() which will convert all keys to numerical keys.

Also \array_splice() needs the offset, not the key! as the second parameter.

Code

<?php

    $array = [0 => "a", 1 => "b", 2 => "c"];
    \array_splice($array, 1, 1);
                        //↑ Offset which you want to delete

?>

Output

[
    [0] => a
    [1] => c
]

array_splice() same as \unset() take the array by reference, and this means you don't want to assign the return values of those functions back to the array.

Delete multiple array elements

If you want to delete multiple array elements and don't want to call \unset() or \array_splice() multiple times you can use the functions \array_diff() or \array_diff_key() depending on if you know the values or the keys of the elements which you want to delete.

\array_diff() method

If you know the values of the array elements which you want to delete, then you can use \array_diff(). As before with \unset() it won't change/reindex the keys of the array.

Code

<?php

    $array = [0 => "a", 1 => "b", 2 => "c"];
    $array = \array_diff($array, ["a", "c"]);
                               //└────────┘→ Array values which you want to delete

?>

Output

[
    [1] => b
]

\array_diff_key() method

If you know the keys of the elements which you want to delete, then you want to use \array_diff_key(). Here you have to make sure you pass the keys as keys in the second parameter and not as values. Otherwise, you have to flip the array with \array_flip(). And also here the keys won't change/reindex.

Code

<?php

    $array = [0 => "a", 1 => "b", 2 => "c"];
    $array = \array_diff_key($array, [0 => "xy", "2" => "xy"]);
                                    //↑           ↑ Array keys which you want to delete
?>

Output

[
    [1] => b
]

Also if you want to use \unset() or \array_splice() to delete multiple elements with the same value you can use \array_keys() to get all the keys for a specific value and then delete all elements.

2641
2/19/2019 10:51:20 AM

It should be noted that unset() will keep indexes untouched, which is what you'd expect when using string indexes (array as hashtable), but can be quite surprising when dealing with integer indexed arrays:

$array = array(0, 1, 2, 3);
unset($array[2]);
var_dump($array);
/* array(3) {
  [0]=>
  int(0)
  [1]=>
  int(1)
  [3]=>
  int(3)
} */

$array = array(0, 1, 2, 3);
array_splice($array, 2, 1);
var_dump($array);
/* array(3) {
  [0]=>
  int(0)
  [1]=>
  int(1)
  [2]=>
  int(3)
} */

So array_splice() can be used if you'd like to normalize your integer keys. Another option is using array_values() after unset():

$array = array(0, 1, 2, 3);

unset($array[2]);
$array = array_values($array);
var_dump($array);
/* array(3) {
  [0]=>
  int(0)
  [1]=>
  int(1)
  [2]=>
  int(3)
} */

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