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

array_unshift — Prepend one or more elements to the beginning of an array

Description

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

Note:

Resets array's internal pointer to the first element.

Parameters

The input array.

The values to prepend.

Return Values

Returns the new number of elements in the array.

Changelog

Examples

Example #1 array_unshift() example

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

The above example will output:

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

See Also

• array_shift() - Shift an element off the beginning of array
• array_push() - Push one or more elements onto the end of array
• array_pop() - Pop the element off the end of array

sergei at gmx dot net ¶

14 years ago

You can preserve keys and unshift an array with numerical indexes in a really simple way if you'll do the following:

$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'
);

Anonymous ¶

10 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:

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 ¶

7 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;
}

Richard Akindele ¶

6 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);

amschroeder at gmail dot com ¶

15 years ago

This becomes a nice little problem if you index your arrays out of order (while manually sorting).  For example:

$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(

php at electricsurfer dot com ¶

18 years ago

even simpler unshifting of a reference !
/**
* @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;
}
?>

robert dot wills at fuzzbrain dot uklinux dot net ¶

20 years ago

Actually this problem with the keys getting reindexed only happens when the keys are numerical:

$a

sahn at hmc dot edu ¶

21 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:

function array_unshift_assoc(&$arr, $key, $val)
{
    $arr = array_reverse($arr, true);
    $arr[$key] = $val;
    $arr = array_reverse($arr, true);
    return count($arr);
}
?>

chris dot NoThxSpam dot given at hp dot com ¶

19 years ago

If you need to change the name of a key without changing its position in the array this function may be useful.

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);
}
?>

John Brooking ¶

16 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:

   array_unshift( $myArray, array_shift( $myArray ));
?>

lagroue ¶

18 years ago

Last version of PHP deprecated unshifting of a reference.
You can use this function instead :

function array_unshift1 (& $ioArray, $iValueWrappedInAnArray) {
    $lNewArray = false;
    foreach (array_keys ($ioArray) as $lKey)
        $lNewArray[$lKey+1] = & $ioArray[$lKey];
    $ioArray = array (& $iValueWrappedInAnArray[0]);
    if ($lNewArray)
        foreach (array_keys ($lNewArray) as $lKey)
             $ioArray[] = & $lNewArray[$lKey];
    return count($ioArray);
} // before last PHP (now generates a deprecation warning)
array_unshift ($a, &$v);
// since last PHP (caution, there is a wrapping array !!)
array_unshift1 ($a, array (&$v));
?>