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.
array_pop
(PHP 4, PHP 5, PHP 7)
array_pop — 배열의 마지막 원소 빼내기
설명
array_pop()은 array의 마지막 값을
빼내고 그 값을 반환하며, array의 길이를 원소 하나
만큼 줄인다. array가 비어있으면 (또는 배열이 아니면)
NULL을 반환한다. 배열이 아닌 것으로 호출하면, 경고가
발생합니다.
인수
-
array -
값을 얻을 배열.
반환값
array의 마지막 값을 반환합니다.
array가 비어있으면(또는 배열이 아니면) NULL을
반환합니다.
예제
Example #1 array_pop() 예제
<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($stack);
?>
이 코드 수행후, $stack은 3개의 원소를 갖게될것이다:
Array
(
[0] => orange
[1] => banana
[2] => apple
)
그리고 raspberry가 $fruit에 할당됩니다.
참고
- array_push() - 배열의 끝에 하나 이상의 원소를 넣는다
- array_shift() - 배열의 맨 앞에 있는 원소를 시프트
- array_unshift() - 배열의 맨 앞에 하나 이상의 원소를 첨가
add a note
User Contributed Notes 11 notes
elad dot yosifon at gmail dot com ¶
11 years ago
noreply at i-asm dot com ¶
3 years ago
Note that array_pop doesn't issue ANY warning or error if the array is already empty when you try to pop something from it. This is bizarre! And it will cause cascades of errors that are hard to resolve without knowing the real cause.
Rather than an error, it silently returns a NULL object, it appears, so in my case I ended up with warnings elsewhere about accessing elements of arrays with invalid indexes, as I was expecting to have popped an array. This behaviour (and the lack of any warning, when many trivial things are complained about verbosely) is NOT noted in the manual above. Popping an already empty stack should definitely trigger some sort of notice, to help debugging.
Sure, it's probably good practice to wrap the pop in an if (count($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.
mcgroovin at gmail dot com ¶
16 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;
}
?>
rmondragon at gmail dot com ¶
19 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 ( $values ) );
?>
good luck ;)
Alex Chac?n ¶
21 years ago
alex.chacon@terra.com
Hi
Here there is a function that delete a elemente from a array and re calculate indexes
<?php
function eliminarElementoArreglo ($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 $array;
}
?>
doyley3731 at gmail dot com ¶
17 years ago
I had a problem when using this function because my array was made up entirley of numbers, so I have made my own function. Hopefully it will be useful to somebody.
function array_trim_end($array){
$num=count($array);
$num=$num-1;
unset($array[$num]);
return $array;
}
qeremy ¶
12 years ago
For the sake of array_unshift()
:)
<?php
function array_unpop(&$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
)
Anonymous ¶
10 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.
sonetti at hotmail dot com ¶
16 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.
Anonymous ¶
19 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.
Orsi ¶
16 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...
