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PHP - Manual: array_pop

2024-12-22

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 最后一个元素的值，并将 array 的长度减一。

注意: 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 最后一个元素的值。如果 array 是空（或者不是数组），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

示例 #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

add a noteadd a note

User Contributed Notes 11 notes

up
64
elad dot yosifon at gmail dot com
8 years ago
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.
up
3
noreply at i-asm dot com
1 year ago
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.
up
5
mcgroovin at gmail dot com
13 years ago
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;
}
?>
up
3
rmondragon at gmail dot com
17 years ago
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 ;)
up
3
Alex Chac?n
19 years ago
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;
}
?>
up
2
doyley3731 at gmail dot com
14 years ago
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;
}
up
1
Anonymous
8 years ago
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.
up
1
qeremy
10 years ago
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
)
up
1
Anonymous
17 years ago
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.
up
0
sonetti at hotmail dot com
14 years ago
@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.
up
0
Orsi
14 years ago
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...
add a noteadd a note

官方地址：https://www.php.net/manual/en/function.array-pop.php

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