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'
);
array_unshift
(PHP 4, PHP 5)
array_unshift — 一つ以上の要素を配列の最初に加える
説明
int array_unshift
( array &$array
, mixed $var
[, mixed $...
] )
array_unshift() は、array の先頭に指定された要素を加えます。リストの要素は全体として加えられるため、 加えられた要素の順番は変わらないことに注意してください。 配列の数値添字はすべて新たにゼロから振りなおされます。 リテラルのキーについては変更されません。
処理後の array の要素の数を返します。
Example#1 array_unshift() の例
<?php
$queue = array("orange", "banana");
array_unshift($queue, "apple", "raspberry");
?>
上の例の出力は以下となります。
Array ( [0] => apple [1] => raspberry [2] => orange [3] => banana )
array_shift()、 array_push() および array_pop() も参照ください。
array_unshift
sergei at gmx dot net
04-Oct-2007 12:49
04-Oct-2007 12:49
mightye at gmail dot com
10-Aug-2007 09:38
10-Aug-2007 09:38
@John Brooking:
Better performing would most likely be array_values($input)
amschroeder at gmail dot com
27-Mar-2007 02:13
27-Mar-2007 02:13
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';
$recordMonths[2] = '1/%/2007';
for($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
03-Jun-2006 10:54
03-Jun-2006 10:54
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:
array_unshift( $myArray, array_shift( $myArray ));
07-Nov-2005 04:38
function multi_array_search($search_value, $the_array)
{
if (is_array($the_array))
{
foreach ($the_array as $key => $value)
{
$result = multi_array_search($search_value, $value);
if (is_array($result))
{
$return = $result;
array_unshift($return, $key);
return $return;
}
elseif ($result == true)
{
$return[] = $key;
return $return;
}
}
return false;
}
else
{
if ($search_value == $the_array)
{
return true;
}
else return false;
}
}
php at electricsurfer dot com
27-Feb-2004 11:20
27-Feb-2004 11:20
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 09:46
09-Nov-2003 09:46
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 (&$v));
?>
chris dot NoThxSpam dot given at hp dot com
24-Jul-2003 04:17
24-Jul-2003 04:17
If you need to change the name of a key without changing its position in the array this function may be useful.
<?php
function array_key_change($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
31-Jul-2002 11:00
31-Jul-2002 11:00
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 09:04
18-Jul-2002 09:04
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.
jrh_at_geodata.soton.ac.uk
11-Jul-2002 01:30
11-Jul-2002 01:30
I have found array_unshift is a function that should be avoided when unshifting lots of data in large arrays.
In a recent script I wrote, it took approx. 24 seconds to unshift 3500 timestamps to an array, a work around could be to use array_reverse and array_push. Array_push is much faster due to the indexing.
robert dot wills at fuzzbrain dot uklinux dot net
07-Feb-2002 11:02
07-Feb-2002 11:02
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: $val \n";
}
?>
Array
(
[f] => five
[s] => six
[t] => twenty
)
k: f v: five
k: s v: six
k: t v: twenty
Array
(
[0] => zero
[f] => five
[s] => six
[t] => twenty
)
k: 0 v: zero
k: f v: five
k: s v: six
k: t v: twenty
sahn at hmc dot edu
28-Jul-2001 04:21
28-Jul-2001 04:21
If you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return count($arr);
}
?>
matt at synergie dot net
19-Sep-2000 02:20
19-Sep-2000 02:20
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