PHP Remove Element from Array: unset, array_splice

To remove an element from a PHP array by its key, use unset($array[$key]). The element is gone, the other keys stay exactly as they were, and unsetting a key that does not exist is not an error.

<?php
$user = ["name" => "Ada", "email" => "ada@example.com", "password" => "secret"];

unset($user["password"]);
print_r($user);

$colors = ["red", "green", "blue", "yellow"];
unset($colors[1]);
print_r($colors);

Look at the second result: the keys are now 0, 2, 3. unset never renumbers.

Reindex the array after unset

A list with a gap in its keys causes trouble later: a for ($i = 0; ...) loop hits the missing index, and json_encode writes a JSON object instead of an array. array_values() gives you clean keys again.

<?php
$colors = ["red", "green", "blue", "yellow"];
unset($colors[1]);

echo json_encode($colors), "\n";

$colors = array_values($colors);
echo json_encode($colors), "\n";

Remove by position with array_splice

array_splice($array, $offset, $length) removes $length elements starting at position $offset, renumbers the keys, and returns what it removed. A negative offset counts from the end. It can also insert replacement elements in the same call.

<?php
$queue = ["a", "b", "c", "d", "e"];

$removed = array_splice($queue, 1, 2);
print_r($removed);
print_r($queue);

// Remove the second to last element
array_splice($queue, -2, 1);
print_r($queue);

// Replace one element with two
$letters = ["x", "y", "z"];
array_splice($letters, 1, 1, ["Y1", "Y2"]);
print_r($letters);

array_splice works on positions, not keys: on an associative array it removes by place in the order, and it keeps string keys. The array_slice page compares it with array_slice, which copies a part without changing the original.

Remove an element by value

array_diff($array, [$value]) returns the array without every element equal to $value, keeping the keys of the rest. To remove only the first match, find its key with array_search and unset it.

<?php
$tags = ["php", "draft", "arrays", "draft", "tips"];

// Every "draft"
print_r(array_diff($tags, ["draft"]));

// Several values at once
print_r(array_values(array_diff($tags, ["draft", "tips"])));

// Only the first "draft"
$key = array_search("draft", $tags);
if ($key !== false) {
    unset($tags[$key]);
}
print_r($tags);

array_diff compares values as strings, so array_diff([1, "1", 2], [1]) removes both the integer and the string. When the condition is more than "equals this value", use array_filter with a callback.

Remove the first or last element

array_shift() removes the first element and array_pop() removes the last. Both return the element they removed, which makes them handy for queues and stacks.

<?php
$tasks = ["write", "test", "deploy"];

$first = array_shift($tasks);
$last = array_pop($tasks);

echo "First: $first\n";
echo "Last: $last\n";
print_r($tasks);

array_shift renumbers numeric keys from 0. array_pop does not need to, since the gap is at the end.

Remove several keys at once

unset accepts several elements in one call. To remove a list of keys you have in an array, flip it with array_flip() so the names become keys, then pass it to array_diff_key().

<?php
$row = ["id" => 7, "name" => "Ada", "token" => "x1", "salt" => "y2", "role" => "admin"];

$copy = $row;
unset($copy["token"], $copy["salt"]);
print_r($copy);

$hidden = ["token", "salt", "role"];
print_r(array_diff_key($row, array_flip($hidden)));

Common mistake: unset with array_search when the value is missing

array_search returns false when it finds nothing, and false used as an array key becomes 0. So this line deletes the first element whenever the value is not in the array:

<?php
$fruits = ["apple", "banana", "cherry"];

// "grape" is not there, array_search returns false, false becomes key 0
unset($fruits[array_search("grape", $fruits)]);
print_r($fruits); // apple is gone

// Correct: check the result with !== false
$fruits = ["apple", "banana", "cherry"];
$key = array_search("grape", $fruits);
if ($key !== false) {
    unset($fruits[$key]);
}
print_r($fruits);

Always store the result of array_search and compare it with !== false before you use it as a key. A plain if ($key) is not enough either: a match at index 0 is falsy too.