array_search
Just a useful version which returns a simple array with the first key and value. Porbably a better way of doing it, but it works for me ;-)
<?php
function array_kshift(&$arr)
{
list($k) = array_keys($arr);
$r = array($k=>$arr[$k]);
unset($arr[$k]);
return $r;
}
// test it on a simple associative array
$arr = array('x'=>'ball','y'=>'hat','z'=>'apple');
print_r($arr);
print_r(array_kshift($arr));
print_r($arr);
?>
Output:
Array
(
[x] => ball
[y] => hat
[z] => apple
)
Array
(
[x] => ball
)
Array
(
[y] => hat
[z] => apple
)
array_shift
(PHP 4, PHP 5)
array_shift — Estrae l'elemento alla testa dell'array
Descrizione
array_shift() estrae il primo elemento di array e lo restituisce, accorciando array di un elemento e spostando tutti gli altri all'indietro. Tutte le chiavi numeriche verranno modificate al fine di iniziare il conteggio da zero, mentre gli indici alfabetici non verranno modificati. Se array è vuoto (o non è un array), viene restituito NULL.
Nota: Questa funzione farà il reset() del puntatore dell'array dopo l'uso.
Example #1 esempio di array_shift()
<?php
$pila = array("arancia", "banana", "mela", lampone");
$frutto = array_shift($pila);
print_r($pila);
?>
In questo modo $pila rimarrà con 3 elementi:
Array ( [0] => banana [1] => mela [2] => lampone )
e arancia sarà assegnata a $frutto.
Vedere anche array_unshift(), array_push() e array_pop().
add a note
User Contributed Notesarray_shift
nospam at dyce dot losethisbit dot com
02-Jul-2008 05:15
02-Jul-2008 05:15
Maikel
19-Feb-2008 09:43
19-Feb-2008 09:43
In response to nando_f at nothingsimple dot com
The example is correct, array_shift do an unset to first element because the parameter is passed by reference
Ben
02-Oct-2007 09:17
02-Oct-2007 09:17
baughmankr at appstate dot edu, I think this is more efficient.
<?php
function array_shorten($arr)
{
list($k) = array_keys($arr);
unset($arr[$k]);
return $arr;
}
?>
baughmankr at appstate dot edu
18-Sep-2007 02:04
18-Sep-2007 02:04
I needed to remove the first set of keys and values from an associative array. Had to write this function:
function shortenArray($_arr)
{
$i=1;
$_shorter=array();
foreach ($_arr as $k => $v)
{
if ($i != 1)
{
$_shorter[$k] = $v;
}
$i++;
}
return $_shorter;
}
dmhouse at gmail dot com
08-Aug-2007 01:54
08-Aug-2007 01:54
If you want a version of array_shift() that works non-destructively (i.e., an easy function to grab the first element of the array without modifying the array), try reset().
Traps
09-Jul-2007 10:52
09-Jul-2007 10:52
For those that may be trying to use array_shift() with an array containing references (e.g. working with linked node trees), beware that array_shift() may not work as you expect: it will return a *copy* of the first element of the array, and not the element itself, so your reference will be lost.
The solution is to reference the first element before removing it with array_shift():
<?php
// using only array_shift:
$a = 1;
$array = array(&$a);
$b =& array_shift($array);
$b = 2;
echo "a = $a, b = $b<br>"; // outputs a = 1, b = 2
// solution: referencing the first element first:
$a = 1;
$array = array(&$a);
$b =& $array[0];
array_shift($array);
$b = 2;
echo "a = $a, b = $b<br>"; // outputs a = 2, b = 2
?>
C_Prevost at myob
30-Apr-2007 04:52
30-Apr-2007 04:52
no, it demonstrates quite well that it removes the first element in the original array, updating the keys, and that it also returns the original first element.
nando_f at nothingsimple dot com
27-Apr-2007 08:42
27-Apr-2007 08:42
I believe the example for array_shift is incorrect.
The print_r has the wrong variable.
-NF
richard at happymango dot me dot uk
12-Apr-2007 06:09
12-Apr-2007 06:09
If you want to loop through an array, removing its values one at a time using array_shift() but also want the key as well, try this.
<?php
while($key = key($array))
{
$value = array_shift($array);
//code goes here
}
?>
its like foreach but each time the value is removed from the array so it eventually ends up empty
<?php
//example below
$airports = array
(
"LGW" => "London Gatwick",
"LHR" => "London Heathrow",
"STN" => "London Stanstead"
);
echo count($airports)." Airport in the array<br /><br />";
while($key = key($airports))
{
$value = array_shift($airports);
echo $key." is ".$value."<br />";
}
echo "<br />".count($airports)." Airport left in the array";
?>
Example Outputs:
3 Airport in the array
LGW is London Gatwick
LHR is London Heathrow
STN is London Stanstead
0 Airport left in the array
François
27-Oct-2006 08:35
27-Oct-2006 08:35
Note that array_shift() can be rather time consuming. Whenever possible, you should consider using array_slice() instead.
Consider the following code :
$monthlyHits = 0;
reset ($hitsArray);
foreach($hitsArray as $visitTime ) {
if ($visitTime < $monthStart ) {
array_shift($hitsArray);
$monthlyHits++;
}
}
This could be replaced by :
$monthlyHits = 0;
reset ($hitsArray);
foreach($hitsArray as $visitTime ) {
if ($visitTime < $monthStart ) {
$monthlyHits++;
}
}
$monthlyHits = array_slice($hitsArray,$monthlyHits);
Here is a benchmark I did on a 10 000 rows array :
First method, 9000 mili-seconds.
Second method, 4 mili-seconds
alreece45 at yahoo dot com
09-Aug-2006 08:13
09-Aug-2006 08:13
I haven't really read into it, but if you're complaining about a change in PHP 5.0.5 that made it so you couldn't do:
<?php
$val = array_shift(preg_split());
?>
or
<?php
$val = array_shit(function_that_returns_array);
?>
Then you're not using this function correctly. This function's argument is supposed to be a pointer to a variable. It then modifies that variable and returns a value. When you specify a function, php CAN NOT modify the return value of that function. It should be common sense but apparently its not.
Also, on a efficiency note, you might want to consider using another function such as reset or perhaps making your own function such as below:
<?php
function first_element($array) {
return reset($array);
}
?>
Unless of course for some reason you need to save the microseconds this takes.
}
bmr at ediweb dot org
31-May-2006 07:27
31-May-2006 07:27
If the array has non-numerical keys, array_shift extracts the first element, whichever is the key, and recompute the numerical keys, if there are any. Ie :
$array = array("c" => "ccc", 0 => "aaa", "d" => "ddd", 5 => "bbb");
$first = array_shift($array);
echo '$first = ' . $first . ', $array = ' . var_export($array, true);
will display :
$first = ccc, $array = array ( 0 => 'aaa', 'd' => 'ddd', 1 => 'bbb', )
It means that array_shift works with associative arrays too, and leaves the keys unchanged if they are non-numerical.
19-Sep-2005 07:57
<?php
//----------------------------------------------------------
// The combination of array_shift/array_unshift
// greatly simplified a function I created for
// generating relative paths. Before I found them
// the algorithm was really squirrely, with multiple
// if tests, length calculations, nested loops, etc.
// Great functions.
//----------------------------------------------------------
function create_relative_path($inSourcePath, $inRefPath)
{
// break strings at slashes
$s_parts = explode('/', $inSourcePath);
$r_parts = explode('/', $inRefPath);
// delete items up to the first non-equal part
while ($s_parts[0] === $r_parts[0])
{
array_shift($s_parts);
array_shift($r_parts);
}
// add wild card to r_parts for each remaining
// item of s_parts
while ($s_parts[0])
{
array_unshift($r_parts, '..');
array_shift($s_parts);
}
return implode('/', $r_parts);
}
//----------------------------------------------------------
// Example:
// Given a source path $sp generates the relative
// location of $rp. $sp could be assigned using
// $_SERVER['PHP_SELF'] but it's hardcoded for
// the example.
//----------------------------------------------------------
$sp = '/WebServer/Documents/MyBigProject/php/project_script.php';
$rp = '/WebServer/Documents/MyLibraries/lib_script.php';
// plugging them into the function
$rel_path = create_relative_path($sp, $rp);
// yeilds
'../../../MyLibraries/lib_script.php'
// and it could be used like
include_once(create_relative_path($_SERVER['PHP_SELF'], $rp));
lukasz dot dywicki DEL at gmail dot com
27-Jul-2005 05:48
27-Jul-2005 05:48
Im using this function to browse arrays from database. For example data:
<?php
$data = array(
array('row 1-cell 1','row 1-cell 2'),
array('row 2-cell 1','row 2-cell 2'),
array('row 3-cell 1','row 3-cell 2'),
);
while($row=array_shift($data)) {
echo $row[0];
}
?>
Output:
row 1-cell 1
row 2-cell 1
row 3-cell 1
arturo {dot} ronchi {at} gmail {dot} com
20-Apr-2005 06:24
20-Apr-2005 06:24
Here is a little function if you would like to get the top element and rotate the array afterwards.
function array_rotate(&$arr)
{
$elm = array_shift($arr);
array_push($arr, $elm);
return $elm;
}
09-Feb-2005 04:27
This function will save the key values of an array, and it will work in lower versions of PHP:
<?php
function array_shift2(&$array){
reset($array);
$key = key($array);
$removed = $array[$key];
unset($array[$key]);
return $removed;
}
?>
James McGuigan
14-Dec-2004 11:26
14-Dec-2004 11:26
while(array_shift()) can be used to process multiple arrays and/or database results in a single loop. The || short circuts and only evaluates the first statement until it runs out of data.
It can help to reduce duplicated code (the rule is code once and once only).
Note that each ($row = ) statement much be encased in ()'s otherwise you will get funny results. If you use two array_shift($array) statements and forget the ()'s, you will repeatedly get the first element of the first array for the for the count of the $array.
<?php
require_once('class.db.php');
$sql = "SELECT title FROM links";
$result = mysql_query($sql, $db->connection);
$defaults = array(
array('title' => 'None'),
array('title' => 'Unknown')
);
while ( ($row = mysql_fetch_assoc($result))
|| ($row = array_shift($defaults)))
{
echo $row['title'] . "<br>";
}
?>
This will print out (depending on database contents):
Title1
Title2
Title3
...
None
Unknown
alex at netflex dot nl
13-Mar-2003 10:55
13-Mar-2003 10:55
Hi,
if you want to shift the first element of a large array (more than 10.000?) and it must realy fast then you can use this better:
<?php
reset($array);
list($oldKey, $oldElement) = each($array);
unset($array[$oldKey]);
?>
note: the index wil not be changed (not reindexed)