array_unique
Whilst experimenting with the function Anonymous posted below I noticed there was a small error... try this correction:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return $arr;
}
?>
array_unshift
(PHP 4, PHP 5)
array_unshift — Prepend one or more elements to the beginning of an array
Description
array_unshift() prepends passed elements to the front
of the array. Note that the list of elements is
prepended as a whole, so that the prepended elements stay in the same
order. All numerical array keys will be modified to start counting from
zero while literal keys won't be touched.
Parameters
-
array -
The input array.
-
var -
The prepended variable.
Return Values
Returns the new number of elements in the array.
Examples
Example #1 array_unshift() example
<?php
$queue = array("orange", "banana");
array_unshift($queue, "apple", "raspberry");
print_r($queue);
?>
The above example will output:
Array
(
[0] => apple
[1] => raspberry
[2] => orange
[3] => banana
)
See Also
- array_shift() - Shift an element off the beginning of array
- array_push() - Push one or more elements onto the end of array
- array_pop() - Pop the element off the end of array
add a note
User Contributed Notes
array_unshift
Anonymous
09-Feb-2012 09:13
Anonymous
19-Nov-2011 09:44
Sahn's example almost works but has a small error. Try it like this if you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
return = array_reverse($arr, true);
}
?>
Rafael M. Salvioni
12-Jun-2008 09:52
This function inserts a element in any position of the Array, by reference.
NOTE: The array is converted for a numeric array.
<?php
/**
* Function array_insert().
*
* Returns the new number of the elements in the array.
*
* @param array $array Array (by reference)
* @param mixed $value New element
* @param int $offset Position
* @return int
*/
function array_insert(&$array, $value, $offset)
{
if (is_array($array)) {
$array = array_values($array);
$offset = intval($offset);
if ($offset < 0 || $offset >= count($array)) {
array_push($array, $value);
} elseif ($offset == 0) {
array_unshift($array, $value);
} else {
$temp = array_slice($array, 0, $offset);
array_push($temp, $value);
$array = array_slice($array, $offset);
$array = array_merge($temp, $array);
}
} else {
$array = array($value);
}
return count($array);
}
?>
sergei at gmx dot net
03-Oct-2007 08:49
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'
);
amschroeder at gmail dot com
26-Mar-2007 09:13
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...
John Brooking
02-Jun-2006 06:54
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 ));
?>
php at electricsurfer dot com
26-Feb-2004 06:20
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;
}
?>
lagroue
09-Nov-2003 04:46
Last version of PHP deprecated unshifting of a reference.
You can use this function instead :
<?php
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 (&$v));
?>
chris dot NoThxSpam dot given at hp dot com
23-Jul-2003 12:17
If you need to change the name of a key without changing its position in the array this function may be useful.
<?php
function array_key_change($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);
}
?>
rsmith_NOSPAM_ at _NOSPAM_unitec dot ac dot nz
30-Jul-2002 07:00
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.
TimHyde at C21Technology dot com
18-Jul-2002 05:04
A simpler way to implement an array_unshift with key=>value pairs (i.e. similar to the example using array_reverse above) is to use array_merge. i.e.
<?php
$arrayone=array_merge(array("newkey"=>"newvalue"),$arrayone);
?>
Obviously you need to take care when adding numeric or duplicate keys.
robert dot wills at fuzzbrain dot uklinux dot net
07-Feb-2002 06:02
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: $val \n";
}
?>
Array
(
[f] => five
[s] => six
[t] => twenty
)
k: f v: five
k: s v: six
k: t v: twenty
Array
(
[0] => zero
[f] => five
[s] => six
[t] => twenty
)
k: 0 v: zero
k: f v: five
k: s v: six
k: t v: twenty
sahn at hmc dot edu
27-Jul-2001 12:21
If you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return count($arr);
}
?>
matt at synergie dot net
18-Sep-2000 10:20
The behaviour of unshift nearly caught me out.
Not only is the item added at the start of the list but the list is re-indexed too.
<?php
$a = array(5=>"five", 6 =>"six", 20 => "twenty");
while(list($key, $value) = each($a))
echo "k: $key v: $value<BR>\n";
echo "<BR>\n";
array_unshift($a, "zero");
while(list($key, $value) = each($a))
echo "k: $key v: $value<BR>\n";
?>
k: 5 v: five
k: 6 v: six
k: 20 v: twenty
k: 0 v: zero
k: 1 v: five
k: 2 v: six
k: 3 v: twenty