(PHP 4, PHP 5, PHP 7, PHP 8)
array_unshift — Prepend one or more elements to the beginning of an array
DescriptionParametersNote:
Resets array's internal pointer to the first element.
array
The input array.
values
The values to prepend.
Returns the new number of elements in the array.
Example #1 array_unshift() example
<?php
$queue
= [
"orange",
"banana"
];array_unshift($queue, "apple", "raspberry");var_dump($queue);?>
The above example will output:
array(4) {
[0] =>
string(5) "apple"
[1] =>
string(9) "raspberry"
[2] =>
string(6) "orange"
[3] =>
string(6) "banana"
}
Example #2 Usage with associative arrays
If one associative array is prepended to another associative array, the prepended array is numerically indexed into the former array.
<?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);?>
The above example will output:
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"
}
} 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'
); rsmith_NOSPAM_ at _NOSPAM_unitec dot ac dot nz ¶
23 years ago
array_merge() will also reindex (see array_merge() manual entry), but the '+' operator won't, so...
<?php
$arrayone=array("newkey"=>"newvalue") + $arrayone;
?>
does the job. Anonymous ¶
13 years ago
Sahn's example almost works but has a small error. Try it like this if you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
return = array_reverse($arr, true);
}
?>
daniel at smallboxcms dot com ¶
10 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;
} amschroeder at gmail dot com ¶
18 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: $singleMonth <br />";
}
?>
Produces:
singleMonth: 3/%/2007
singleMonth: 2/%/2007
singleMonth: 1/%/2007
singleMonth: 8/%/2006
singleMonth: 7/%/2004
singleMonth: 12/%/2000
singleMonth: 11/%/2000
singleMonth: 10/%/2000
singleMonth: %
singleMonth: 8/%/2006
singleMonth: 7/%/2004
singleMonth: 3/%/2007
singleMonth: 2/%/2007
singleMonth: 12/%/2000
singleMonth: 11/%/2000
singleMonth: 10/%/2000
singleMonth: 1/%/2007
It reindexes them based on the order they were created. It seems like if an array has all numeric indexes, then it should reindex them based on the order of their index. Just my opinion...
php at electricsurfer dot com ¶
21 years ago
even simpler unshifting of a reference !
<?php
function array_unshift_ref(&$array, &$value)
{
$return = array_unshift($array,'');
$array[0] =& $value;
return $return;
}
?>
23 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 eliasritter168667 at gmail dot com ¶
1 year 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);
} Richard Akindele ¶
9 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"), $plans);
chris dot NoThxSpam dot given at hp dot com ¶
22 years ago
If you need to change the name of a key without changing its position in the array this function may be useful.
<?php
function array_key_change($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);
}
?>
sahn at hmc dot edu ¶
24 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);
}
?>
John Brooking ¶
19 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 ));
?>
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