array_pop

(PHP 4, PHP 5, PHP 7, PHP 8)

array_pop — 弹出数组最后一个单元（出栈）

说明

array_pop ( array &$array ) : mixed

array_pop() 弹出并返回 array 数组的最后一个单元，并将数组 array 的长度减一。

Note: 使用此函数后会重置（reset()）array 指针。

参数

array

需要弹出栈的数组。

返回值

返回 array 的最后一个值。如果 array 是空（如果不是一个数组），将会返回 null 。

错误／异常

调用此函数去处理非数组的值，会产生 E_WARNING 级别的错误。

范例

Example #1 array_pop() 例子

<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($stack);
?>

经过此操作后，$stack 将只有 3 个单元： 

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
)

并且 raspberry 将被赋给 $fruit。

参见

User Contributed Notes

noreply at i-asm dot com 09-May-2021 11:18
Note that array_pop doesn't issue ANY warning or error if the array is already empty when you try to pop something from it. This is bizarre! And it will cause cascades of errors that are hard to resolve without knowing the real cause.

Rather than an error, it silently returns a NULL object, it appears, so in my case I ended up with warnings elsewhere about accessing elements of arrays with invalid indexes, as I was expecting to have popped an array. This behaviour (and the lack of any warning, when many trivial things are complained about verbosely) is NOT noted in the manual above. Popping an already empty stack should definitely trigger some sort of notice, to help debugging.

Sure, it's probably good practice to wrap the pop in an if (count($array)) but that should be suggested in the manual, if there's no error returned for trying something that should fail and obviously isn't expected to return a meaningful result.
Anonymous 06-Nov-2015 04:02
Let's "do stuff" with array_pop()

<?php

$dependecyInjection = ['globalState' => 'isHorrible'];

$workQueue = array_reverse($workQueue); // O(n)
// While we have stuff to do..... = [[ {function}, $params.... ], [], []...]
while (!empty($workQueue)) {

  // O(1) : And resize array. (maybe also memory size ?)
  $work = array_pop($workQueue);

  // If not `muted`, invoke the worker function....
  if (isset($work[0])) {
    $processor = array_shift($work);
    if ($moreWork = $processor->__invoke($work, $dependecyInjection)) { // <== Do stuff.
      // O(n) : add new stuff to the END of array ! (FIFO)
      $outputCommands += array_reverse($moreWork);
    }
  }
}
Anonymous 28-Feb-2014 08:21
Strict Standards will be thrown out if you put exploded array in array_pop:
<?php
$a = array_pop(explode(",", "a,b,c"));
echo $a;
?>

You will see:
PHP Strict Standards:  Only variables should be passed by reference in - on line 2

Strict Standards: Only variables should be passed by reference in - on line 2
c

Notice that, you should assign a variable for function explode, then pass the variable reference into array_pop to avoid the Strict Standard warning.
elad dot yosifon at gmail dot com 10-Aug-2013 06:45
Notice:
the complexity of array_pop() is O(1).
the complexity of array_shift() is O(n).
array_shift() requires a re-index process on the array, so it has to run over all the elements and index them.
qeremy 07-Mar-2012 11:26
For the sake of array_unshift()
:)

<?php
function array_unpop(&$arr) {
    $args = func_get_args(); unset($args[0]);
    $tarr = array();
    foreach ($args as $arg) {
        $tarr[] = $arg;
    }
    $arr = array_merge($arr, $tarr);
}

$queue = array("orange", "banana");
array_unpop($queue, "apple", "raspberry");
print_r($queue);
?>

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
    [3] => raspberry
)
Igor Feghali 04-Feb-2009 09:18
Beware that array_pop() returns a copy of the element (even if the array element is a reference). That means you will get different results on PHP 4 and 5 when dealing with objects.

<?php
$a = new stdClass();
$a->foo = 'bar';

$arr = array(&$a);
$b = array_pop($arr);

$b->foo = 'baz';

var_dump($a);
?>

Output of PHP 5.2.8:
object(stdClass)#1 (1) {
  ["foo"]=>
  string(3) "baz"
}

Output of PHP 4.4.9:
object(stdClass)(1) {
  ["foo"]=>
  string(3) "bar"
}

For more information please refer to:
http://br2.php.net/manual/en/language.oop5.references.php
mcgroovin at gmail dot com 23-Oct-2008 12:13
I wrote a simple function to perform an intersect on multiple (unlimited) arrays.

Pass an array containing all the arrays you want to compare, along with what key to match by.

<?php
function multipleArrayIntersect($arrayOfArrays, $matchKey)
{
    $compareArray = array_pop($arrayOfArrays);
   
    foreach($compareArray AS $key => $valueArray){
        foreach($arrayOfArrays AS $subArray => $contents){
            if (!in_array($compareArray[$key][$matchKey], $contents)){
                unset($compareArray[$key]);
            }
        }
    }

    return $compareArray;
}
?>
sonetti at hotmail dot com 05-Feb-2008 01:15
@smp_info
I think you are still tired. What would be wrong with:

<?php
$array = array('one', 'two', 'three', 'four');

//pop the last element off
array_pop($array);

//$array == array('one', 'two', 'three');
?>

As the documentation clearly notes, array_pop() not only returns the last element, but actually removes it from the array wich is passed by reference. Calling array_diff is a waste of resources.
Orsi 10-Jan-2008 07:05
Hi,

Here is a simple function which delete one element from the array (with value):
<?php
/*
* This function deletes the given element from a one-dimension array
* Parameters: $array:    the array (in/out)
*             $deleteIt: the value which we would like to delete
*             $useOldKeys: if it is false then the function will re-index the array (from 0, 1, ...)
*                          if it is true: the function will keep the old keys
* Returns true, if this value was in the array, otherwise false (in this case the array is same as before)
*/
function deleteFromArray(&$array, $deleteIt, $useOldKeys = FALSE)
{
    $tmpArray = array();
    $found = FALSE;
    foreach($array as $key => $value)
    {
        if($value !== $deleteIt)
        {
            if(FALSE === $useOldKeys)
            {
                $tmpArray[] = $value;
            }
            else
            {
                $tmpArray[$key] = $value;
            }
        }
        else
        {
            $found = TRUE;
        }
    }
  
    $array = $tmpArray;
  
    return $found;
}
?>

Maybe it will help somebody...
doyley3731 at gmail dot com 31-Oct-2007 04:37
I had a problem when using this function because my array was made up entirley of numbers, so I have made my own function.  Hopefully it will be useful to somebody.

function array_trim_end($array){

$num=count($array);
$num=$num-1;
unset($array[$num]);

return $array;
}
rmondragon at gmail dot com 07-Jun-2005 02:03
In a previous example ...
<?php
function array_trim ( $array, $index ) {
   if ( is_array ( $array ) ) {
     unset ( $array[$index] );
     array_unshift ( $array, array_shift ( $array ) );
     return $array;
     }
   else {
     return false;
     }
   }
?>

This have a problem. if u unset the last value and then use
<?
array_unshift ( $array, array_shift ( $array ) );
?>

will return a :  Array ( [0] => )
so u can fix it using...

<?php
if (count($array) > 0) array_unshift ( $values, array_shift ( $values ) );           
?>

good luck ;)
15-Dec-2004 08:29
strrchr is a lot more useful than the other example using array_pop for finding the extension of a file. For example:

<?php
$ext = strrchr($filename, ".");
?>

$ext will contain the extension of the file, including a ".", if the file has an extension, and FALSE if the file has no extension. If the file has multiple extensions, such as "filename.tar.gz", then this construction will just return the last extension.
eddie at metafoundry dot com 25-Nov-2004 08:35
Quick way to get the extension from a file name using array_pop:

$ext = array_pop(explode(".",$filename));
30-Mar-2004 01:55
A function to delete an array value that recalculates the index ( its very short and easy to understand ).
Hope this might help someone...

<?php
/* Usage:
    $array : Array
    $indey : Integer
   
    The value of $array at the index $index will be
    deleted by the function.
*/
function array_trim ( $array, $index ) {
   if ( is_array ( $array ) ) {
      unset ( $array[$index] );
      array_unshift ( $array, array_shift ( $array ) );
      return $array;
      }
   else {
      return false;
      }
   }
?>
ryan8613(at)hotmail(dot)com 08-Jun-2003 06:10
A function that may help some out, considering it's pretty much the one mentioned previously...

<?php
function array_trim($arr, $indice) {
        if(!isset($indice)) {
                $indice = count($arr)-1;
        }
        unset($arr[$indice]);
        array_shift($arr);
        return $arr;
}
?>

It cuts the given index value off of the array, but without the shift, if  the 'index' value isn't given, it cuts off the end value.
Alex Chac?n 28-Feb-2003 05:16
alex.chacon@terra.com
Hi
Here there is a function that delete a elemente from a array and re calculate indexes

<?php
function eliminarElementoArreglo ($array, $indice)
{
    if (array_key_exists($indice, $array))
    {
        $temp = $array[0];
        $array[0] = $array[$indice];
        $array[$indice] = $temp;
        array_shift($array);

        //reacomodamos ?ndices
        for ($i = 0 ; $i < $indice ; $i++)
        {
            $dummy = $array[$i];
            $array[$i] = $temp;
            $temp = $dummy;
        }
    }
    return $array;
}
?>
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