Advertisement
Advertisement


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.

2019/10/17
1
2576
10/17/2019 10:22:33 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()

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.

2020/07/07
2955
7/7/2020 7:12:23 PM


  // Our initial array
  $arr = array("blue", "green", "red", "yellow", "green", "orange", "yellow", "indigo", "red");
  print_r($arr);

  // Remove the elements who's values are yellow or red
  $arr = array_diff($arr, array("yellow", "red"));
  print_r($arr);

This is the output from the code above:

Array
(
    [0] => blue
    [1] => green
    [2] => red
    [3] => yellow
    [4] => green
    [5] => orange
    [6] => yellow
    [7] => indigo
    [8] => red
)

Array
(
    [0] => blue
    [1] => green
    [4] => green
    [5] => orange
    [7] => indigo
)

Now, array_values() will reindex a numerical array nicely, but it will remove all key strings from the array and replace them with numbers. If you need to preserve the key names (strings), or reindex the array if all keys are numerical, use array_merge():

$arr = array_merge(array_diff($arr, array("yellow", "red")));
print_r($arr);

Outputs

Array
(
    [0] => blue
    [1] => green
    [2] => green
    [3] => orange
    [4] => indigo
)
2019/02/19

$key = array_search($needle, $array);
if ($key !== false) {
    unset($array[$key]);
}
2019/02/19

unset($array[$index]);
2008/12/15

If you have a numerically indexed array where all values are unique (or they are non-unique but you wish to remove all instances of a particular value), you can simply use array_diff() to remove a matching element, like this:

$my_array = array_diff($my_array, array('Value_to_remove'));

For example:

$my_array = array('Andy', 'Bertha', 'Charles', 'Diana');
echo sizeof($my_array) . "\n";
$my_array = array_diff($my_array, array('Charles'));
echo sizeof($my_array);

This displays the following:

4
3

In this example, the element with the value 'Charles' is removed as can be verified by the sizeof() calls that report a size of 4 for the initial array, and 3 after the removal.

2012/11/26

Also, for a named element:

unset($array["elementName"]);
2018/11/13

Source: https://stackoverflow.com/questions/369602
Licensed under: CC-BY-SA with attribution
Not affiliated with: Stack Overflow
Email: [email protected]