Better way to unset multiple array elements

Question

The deal here is that I have an array with 17 elements. I want to get the elements I need for a certain time and remove them permanently from the array.

Here's the code:

$name = $post['name'];
$email = $post['email'];
$address = $post['address'];
$telephone = $post['telephone'];
$country = $post['country'];

unset($post['name']);
unset($post['email']);
unset($post['address']);
unset($post['telephone']);
unset($post['country']);

Yes the code is ugly, no need to bash. How do I make this look better?

This is almost certainly an [XY Problem](https://meta.stackexchange.com/q/66377/352329). There probably isn't any beneficial reason to unset these elements. And if you have concerns regarding variable scope, there may be better ways to address them than explicitly unsetting, but we cannot advise without more/better context. — mickmackusa, May 10 '22 at 07:13

score 170 · Answer 1 · edited Jan 26 '23 at 09:20

170

Use array_diff_key to remove

$remove = ['telephone', 'country'];

$remaining = array_diff_key($post, array_flip($remove));

You could use array_intersect_key if you wanted to supply an array of keys to keep.

edited Jan 26 '23 at 09:20

Martijn

15,791
4
36
68

answered Nov 19 '15 at 10:13

Tim

4,471
5
36
42

smart but slow for large input arrays. foreach unset seems much faster with big input arrays and (at least) relatively small number of keys to unset. – slepic Oct 26 '19 at 07:07
1

Be careful: if the value of the field you want to remove is equal to the index of the (flipped) element you want to remove the key will not be removed. It can lead to security problems by exposing data. Can see the results here: https://replit.com/@xbeat/unset-array-of-key#index.php – Giuseppe Canale Jun 15 '22 at 15:00

alex · Answer 2 · 2012-12-28T12:30:54.613

109

It looks like the function extract() would be a better tool for what you're trying to do (assuming it's extract all key/values from an array and assign them to variables with the same names as the keys in the local scope). After you've extracted the contents, you could then unset the entire $post, assuming it didn't contain anything else you wanted.

However, to actually answer your question, you could create an array of the keys you want to remove and loop through, explicitly unsetting them...

$removeKeys = array('name', 'email');

foreach($removeKeys as $key) {
   unset($arr[$key]);
}

...or you could point the variable to a new array that has the keys removed...

$arr = array_diff_key($arr, array_flip($removeKeys));

...or pass all of the array members to unset()...

unset($arr['name'],  $arr['email']);

edited Dec 28 '12 at 12:30

answered Oct 25 '11 at 05:20

alex

479,566
201
878
984

10

[array_diff_key()](http://php.net/manual/en/function.array-diff-key.php) is a nice solution. Thought I would add that you can use [array_intersect_key()](http://php.net/manual/en/function.array-intersect-key.php) to do the reverse, keep only certain elements – batfastad Jul 26 '14 at 00:34
By chance I was just doing this thing with the foreach unset. Then I thought there could be a better solution. Google lead me here. So i tried array_diff_key and it turns out that it is much much slower than foreach for large input arrays (at least when the number of keys to unset is relatively small.). – slepic Oct 26 '19 at 07:04
Be careful using array_flip solution: if the value of the field you want to remove is equal to the index of the (flipped) element you want to remove the key will not be removed. It can lead to security problems by exposing data. Can see the results here: replit.com/@xbeat/unset-array-of-key#index.php – Giuseppe Canale Jun 15 '22 at 15:06

score 64 · Answer 3 · edited Aug 01 '14 at 08:29

There is another way which is better then the above examples. Source: http://php.net/manual/en/function.unset.php

Instead of looping thorough the entire array and unsetting all its keys, you can just unset it once like so:

Example Array:

$array = array("key1", "key2", "key3");

For the entire array:

unset($array);

For unique keys:

unset($array["key1"]);

For multiple keys in one array:

unset($array["key1"], $array["key2"], $array["key3"] ....) and so on.

I hope this helps you in your development.

score 4 · Answer 4 · answered Dec 02 '13 at 11:17

4

I understand this question is old, but I think an optimal way might be to do this:

$vars = array('name', 'email', 'address', 'phone'); /* needed variables */
foreach ($vars as $var) {
    ${$var} = $_POST[$var]; /* create variable on-the-fly */
    unset($_POST[$var]); /* unset variable after use */
}

Now, you can use $name, $email, ... from anywhere ;)

NB: extract() is not safe, so it's completely out of question!

answered Dec 02 '13 at 11:17

Felix Imafidon

177
6

1

Out of curiosity - why is extract() not safe? – Srdjan Marjanovic Nov 23 '18 at 08:31
@SrdjanMarjanovic https://stackoverflow.com/questions/829407/what-is-so-wrong-with-extract – Andrew Feb 26 '19 at 19:46

score 2 · Answer 5 · answered Jan 12 '21 at 20:09

2

<?php
   $name = $post['name'];
   $email = $post['email'];
   $address = $post['address'];
   $telephone = $post['telephone'];
   $country = $post['country'];



   
   $myArray = array_except($post, ['name', 'email','address','telephone','country']);
   
  print_r($myArray);
  
  
   
  function array_except($array, $keys){
    foreach($keys as $key){
        unset($array[$key]);
    }
    return $array;
  }
?>

answered Jan 12 '21 at 20:09

ahmedkandil

477
3
6

Is this answer not repeating earlier posted insights? – mickmackusa May 10 '22 at 06:18

score 1 · Answer 6 · answered May 29 '22 at 14:20

1

In php unset function can take multiple arguments

$test = ['test1' => 1, 'test2' => 4, 'test34' => 34];

unset($test['test1'], $test['test34']);

Here is this description from documentation

unset(mixed $var, mixed ...$vars): void

answered May 29 '22 at 14:20

Levon Babayan

266
2
18

Better way to unset multiple array elements

6 Answers6

Linked

Related