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(PHP 4, PHP 5)
array_unshift — Fügt ein oder mehr Elemente am Anfang eines Arrays ein
array_unshift() fügt die übergebenen Elemente am Anfang von array ein. Beachten Sie, dass die Liste von Elementen als Ganzes eingefügt wird, sodass die eingefügten Elemente die selbe Reihenfolge haben. Die numerischen Schlüssel werden so modifiziert, dass bei null zu zählen begonnen wird, Strings als Schlüssel bleiben unverändert.
Diese Funktion gibt die neue Anzahl der in array enthaltenen Elemente zurück.
Beispiel #1 array_unshift()
<?php
$queue = array("Orange", "Banane");
array_unshift($queue, "Apfel", "Himbeere");
?>
Als Ergebnis enthält $queue die folgenden Elemente:
Array
(
[0] => Apfel
[1] => Himbeere
[2] => Orange
[3] => Banane
)
Siehe auch array_shift(), array_push() und array_pop().
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);
}
?>
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'
);
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...
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 ));
?>
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;
}
?>
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 (&$v));
?>
If you need to change the name of a key without changing its position in the array this function may be useful.
<?php
function array_key_change($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);
}
?>
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.
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.
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: $val \n";
}
?>
Array
(
[f] => five
[s] => six
[t] => twenty
)
k: f v: five
k: s v: six
k: t v: twenty
Array
(
[0] => zero
[f] => five
[s] => six
[t] => twenty
)
k: 0 v: zero
k: f v: five
k: s v: six
k: t v: twenty
If you need to prepend something to the array without the keys being reindexed and/or need to prepend a key value pair, you can use this short function:
<?php
function array_unshift_assoc(&$arr, $key, $val)
{
$arr = array_reverse($arr, true);
$arr[$key] = $val;
$arr = array_reverse($arr, true);
return count($arr);
}
?>
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
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