array_unshift

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

array_unshiftДобавляет один или несколько элементов в начало массива

Описание

array_unshift(array &$array, mixed ...$values): int

array_unshift() добавляет переданные в качестве аргументов элементы в начало массива array. Обратите внимание, что список элементов добавляется целиком, то есть порядок элементов сохраняется. Все числовые ключи будут изменены таким образом, что нумерация массива будет начинаться с нуля, в то время как строковые ключи останутся прежними.

Замечание:

Функция сбрасывает внутренний указатель массива на первый элемент.

Список параметров

array

Входной массив.

values

Значения для добавления.

Возвращаемые значения

Возвращает новое количество элементов в array.

Список изменений

Версия Описание
7.3.0 Теперь эта функция может быть вызвана с одним параметром. Ранее требовалось минимум два параметра.

Примеры

Пример #1 Пример использования array_unshift()

<?php
$queue
= [
"orange",
"banana"
];

array_unshift($queue, "apple", "raspberry");
var_dump($queue);
?>

Результат выполнения приведённого примера:

array(4) {
  [0] =>
  string(5) "apple"
  [1] =>
  string(9) "raspberry"
  [2] =>
  string(6) "orange"
  [3] =>
  string(6) "banana"
}

Пример #2 Пример использования с ассоциативными массивами

Если один ассоциативный массив добавляется к другому ассоциативному массиву, то добавляемый массив продолжает числовой индекс первого массиве.

<?php
$foods
= [
'apples' => [
'McIntosh' => 'red',
'Granny Smith' => 'green',
],
'oranges' => [
'Navel' => 'orange',
'Valencia' => 'orange',
],
];
$vegetables = [
'lettuce' => [
'Iceberg' => 'green',
'Butterhead' => 'green',
],
'carrots' => [
'Deep Purple Hybrid' => 'purple',
'Imperator' => 'orange',
],
'cucumber' => [
'Kirby' => 'green',
'Gherkin' => 'green',
],
];

array_unshift($foods, $vegetables);
var_dump($foods);

Результат выполнения приведённого примера:

array(3) {
  [0] =>
  array(3) {
    'lettuce' =>
    array(2) {
      'Iceberg' =>
      string(5) "green"
      'Butterhead' =>
      string(5) "green"
    }
    'carrots' =>
    array(2) {
      'Deep Purple Hybrid' =>
      string(6) "purple"
      'Imperator' =>
      string(6) "orange"
    }
    'cucumber' =>
    array(2) {
      'Kirby' =>
      string(5) "green"
      'Gherkin' =>
      string(5) "green"
    }
  }
  'apples' =>
  array(2) {
    'McIntosh' =>
    string(3) "red"
    'Granny Smith' =>
    string(5) "green"
  }
  'oranges' =>
  array(2) {
    'Navel' =>
    string(6) "orange"
    'Valencia' =>
    string(6) "orange"
  }
}

Смотрите также

  • array_shift() - Извлекает первый элемент массива
  • array_push() - Добавляет один или несколько элементов в конец массива
  • array_pop() - Извлекает последний элемент массива

Добавить

Примечания пользователей 12 notes

up
211
sergei at gmx dot net
17 years ago
You can preserve keys and unshift an array with numerical indexes in a really simple way if you'll do the following:

<?php
$someArray
=array(224=>'someword1', 228=>'someword2', 102=>'someword3', 544=>'someword3',95=>'someword4');

$someArray=array(100=>'Test Element 1 ',255=>'Test Element 2')+$someArray;
?>

now the array looks as follows:

array(
100=>'Test Element 1 ',
255=>'Test Element 2'
224=>'someword1',
228=>'someword2',
102=>'someword3',
544=>'someword3',
95=>'someword4'
);
up
37
rsmith_NOSPAM_ at _NOSPAM_unitec dot ac dot nz
22 years ago
array_merge() will also reindex (see array_merge() manual entry), but the '+' operator won't, so...

<?php
$arrayone
=array("newkey"=>"newvalue") + $arrayone;
?>

does the job.
up
35
Anonymous
12 years ago
Sahn's example almost works but has a small error. Try it like this if you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:

<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
return =
array_reverse($arr, true);
}
?>
up
10
daniel at smallboxcms dot com
9 years ago
Anonymous' associative version wasn't working for me, but it did with this small tweak:

function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return $arr;
}
up
2
amschroeder at gmail dot com
17 years ago
This becomes a nice little problem if you index your arrays out of order (while manually sorting). For example:

<?php
$recordMonths
[3] = '8/%/2006';
$recordMonths[4] = '7/%/2004';
$recordMonths[0] = '3/%/2007';
$recordMonths[1] = '2/%/2007';
$recordMonths[5] = '12/%/2000';
$recordMonths[6] = '11/%/2000';
$recordMonths[7] = '10/%/2000';
$recordMonths[2] = '1/%/2007';

for(
$i = 0; $i < count($recordMonths); $i++)
{
$singleMonth = $recordMonths[$i];
echo
"singleMonth: $singleMonth <br />";
}
array_unshift($recordMonths,'%');
for(
$i = 0; $i < count($recordMonths); $i++)
{
$singleMonth = $recordMonths[$i];
echo
"singleMonth: $singleMonth <br />";
}
?>

Produces:

singleMonth: 3/%/2007
singleMonth: 2/%/2007
singleMonth: 1/%/2007
singleMonth: 8/%/2006
singleMonth: 7/%/2004
singleMonth: 12/%/2000
singleMonth: 11/%/2000
singleMonth: 10/%/2000
singleMonth: %
singleMonth: 8/%/2006
singleMonth: 7/%/2004
singleMonth: 3/%/2007
singleMonth: 2/%/2007
singleMonth: 12/%/2000
singleMonth: 11/%/2000
singleMonth: 10/%/2000
singleMonth: 1/%/2007

It reindexes them based on the order they were created. It seems like if an array has all numeric indexes, then it should reindex them based on the order of their index. Just my opinion...
up
2
php at electricsurfer dot com
20 years ago
even simpler unshifting of a reference !
<?php
/**
* @return int
* @param $array array
* @param $value mixed
* @desc Prepend a reference to an element to the beginning of an array. Renumbers numeric keys, so $value is always inserted to $array[0]
*/
function array_unshift_ref(&$array, &$value)
{
$return = array_unshift($array,'');
$array[0] =& $value;
return
$return;
}
?>
up
2
robert dot wills at fuzzbrain dot uklinux dot net
22 years ago
Actually this problem with the keys getting reindexed only happens when the keys are numerical:

<?php

$a
= array("f"=>"five", "s" =>"six", "t" =>
"twenty");

print_r($a);
echo
"\n";
foreach(
$a as $key=>$val)
{
echo
"k: $key v: $val \n";
}

array_unshift($a, "zero");
print_r($a);
echo
"\n";
foreach(
$a as $key=>$val)
{
echo
"k: $key v: $val \n";
}
?>

Array
(
[f] => five
[s] => six
[t] => twenty
)

k: f v: five
k: s v: six
k: t v: twenty
Array
(
[0] => zero
[f] => five
[s] => six
[t] => twenty
)

k: 0 v: zero
k: f v: five
k: s v: six
k: t v: twenty
up
0
eliasritter168667 at gmail dot com
11 months ago
This function helps if you want to prepend a key and value pair to the beginning of an array:

function array_kunshift(array $array, string|int $key, mixed $value): array {
return array_merge([$key => $value], $array);
}
up
0
Richard Akindele
8 years ago
Another way to tack something to the beginning of an array is with array_merge().

$plans = array('AARP'=>'Senior', 'AAA'=>'Automobile Club');

$plans = array_merge(array("BAR"=>"Best Available Rate"), $plans);
up
-1
chris dot NoThxSpam dot given at hp dot com
21 years ago
If you need to change the name of a key without changing its position in the array this function may be useful.

<?php
function array_key_change($Old, $New, $In, $NewVal=NULL) {
$Temp = array();
while(isset(
$Temp[$Old]) == false) {
list(
$k, $v) = each($In);
$Temp[$k] = $v;
unset(
$In[$k]);
}
if(
$NewVal == NULL) {
$NewVal = $Temp[$Old];
}
unset(
$Temp[$Old]);
$Temp = array_reverse($Temp);
$In = array_merge(array($New=>$NewVal), $In);
while(list(
$k,$v) = each($Temp)) {
$In = array_merge(array($k=>$v), $In);
}
return(
$In);
}
?>
up
-2
sahn at hmc dot edu
23 years ago
If you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:

<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return
count($arr);
}
?>
up
-5
John Brooking
18 years ago
I had a need tonight to convert a numeric array from 1-based to 0-based, and found that the following worked just fine due to the "side effect" of renumbering:

<?php
array_unshift
( $myArray, array_shift( $myArray ));
?>
To Top