PHP 7.1.20 Released

list

(PHP 4, PHP 5, PHP 7)

listDeğişkenlere bir dizi gibi atama yapar

Açıklama

array list ( mixed $değişken [, mixed $... ] )

array() gibi bu da bir işlev değil bir dil oluşumudur. list() işlevi tek deyimde birden fazla değişkene atama yapmak için kullanılır.

Değiştirgeler

değişken

Bir değişken.

Dönen Değerler

Atanan dizi döner.

Örnekler

Örnek 1 - list() örnekleri

<?php

$veri 
= array('kahve''uyku''kafein');

// Değişkenlerin tamamını listeleyelim
list($içecek$neyi$güç) = $veri;
echo 
"$içecek $neyi kaçırır, çünkü içinde $güç vardır.\n";

// Bir kısmını listeleyelim
list($içecek, , $güç) = $veri;
echo 
"$içecek $güç içerir.\n";

// Sadece üçüncü kalsın
list( , , $güç) = $veri;
echo 
"Bana $güç lazım!\n";

// list() dizgelerle çalışmaz
list($bar) = "abcde";
var_dump($bar); // NULL
?>

Örnek 2 - list() kullanım örneği

<table>
 <tr>
  <th>Çalışanın adı</th>
  <th>Ücreti</th>
 </tr>

<?php

$sonuç 
mysql_query("SELECT id, ad, ucret FROM personel"$conn);
while (list(
$id$ad$ücret) = mysql_fetch_row($sonuç)) {
    echo 
" <tr>\n" .
          
"  <td><a href=\"info.php?id=$id\">$ad</a></td>\n" .
          
"  <td>$ücret</td>\n" .
          
" </tr>\n";
}

?>

</table>

Örnek 3 - İç içe list() kullanımı

<?php

list($a, list($b$c)) = array(1, array(23));

var_dump($a$b$c);

?>
int(1)
int(2)
int(3)

Örnek 4 - Dizi indisleri ile list() kullanımı

<?php

$veri 
= array('kahve''uyku''kafein');

list(
$a[0], $a[1], $a[2]) = $veri;

var_dump($a);

?>

Aşağıdaki çıktıyı verir (dikkatı ederseniz, eleman sırası list() ile belirtilen sıra ile aynıdır):

array(3) {
  [2]=>
  string(6) "kafein"
  [1]=>
  string(4) "uyku"
  [0]=>
  string(5) "kahve"
}

Notlar

Uyarı

list() değerleri en sağdaki değiştirgeden itibaren atar. Düz değişken kullanıyorsanız bundan dolayı endişelenmeniz gerekmez. Fakat indisli diziler kullanıyorsanız, dizi indislerinin, list()'teki yazılış sırasına göre soldan sağa sıralanacağını düşünürsünüz. Fakat atama sağdan sola doğru yapılır.

Bilginize:

list() sadece sayısal indisli dizilerle çalışır ve indislerin 0'dan başladığı varsayılır.

Ayrıca Bakınız

  • each() - Bir diziden, gösterici konumundaki anahtar değer çiftini döndürdükten sonra göstericiyi bir ilerletir
  • array() - Bir dizi oluşturur
  • extract() - Bir dizideki değişkenleri simge tablosuna dahil eder

add a note add a note

User Contributed Notes 16 notes

up
61
Rhamnia Mohamed
1 year ago
Since PHP 7.1, keys can be specified

exemple :
<?php
$array
= ['locality' => 'Tunis', 'postal_code' => '1110'];

list(
'postal_code' => $zipCode, 'locality' => $locality) = $array;

print
$zipCode; // will output 1110
print $locality; // will output Tunis
?>
up
63
grzeniufication
3 years ago
The example showing that:

$info = array('kawa', 'brązowa', 'kofeina');
list($a[0], $a[1], $a[2]) = $info;
var_dump($a);

outputs:
array(3) {
[2]=>
string(8) "kofeina"
[1]=>
string(5) "brązowa"
[0]=>
string(6) "kawa"
}

One thing to note here is that if you define the array earlier, e.g.:
$a = [0, 0, 0];

the indexes will be kept in the correct order:

array(3) {
  [0]=>
  string(4) "kawa"
  [1]=>
  string(8) "brązowa"
  [2]=>
  string(7) "kofeina"
}

Thought that it was worth mentioning.
up
43
grzeniufication
1 year ago
<?php
/**
* It seems you can skip listed values.
* Here's an example to show what I mean.
*
* FYI works just as well with PHP 7.1 shorthand list syntax.
* Tested against PHP 5.6.30, 7.1.5
*/
$a = [ 1, 2, 3, 4 ];

// this is quite normal use case for list
echo "Unpack all values\n";
list(
$v1, $v2, $v3, $v4) = $a;
echo
"$v1, $v2, $v3, $v4\n";
unset(
$v1, $v2, $v3, $v4);

// this is what I mean:
echo "Skip middle\n";
list(
$v1, , , $v4) = $a;
echo
"$v1, $v2, $v3, $v4\n";
unset(
$v1, $v2, $v3, $v4);

echo
"Skip beginning\n";
list( , ,
$v3, $v4) = $a;
echo
"$v1, $v2, $v3, $v4\n";
unset(
$v1, $v2, $v3, $v4);

echo
"Skip end\n";
list(
$v1, $v2, , ) = $a;
echo
"$v1, $v2, $v3, $v4\n";
unset(
$v1, $v2, $v3, $v4);

echo
"Leave middle\n";
list( ,
$v2, $v3, ) = $a;
echo
"$v1, $v2, $v3, $v4\n";
unset(
$v1, $v2, $v3, $v4);
up
67
chris at chlab dot ch
5 years ago
The example states the following:
<?php
// list() doesn't work with strings
list($bar) = "abcde";
var_dump($bar);
// output: NULL
?>

If the string is in a variable however, it seems using list() will treat the string as an array:
<?php
$string
= "abcde";
list(
$foo) = $string;
var_dump($foo);
// output: string(1) "a"
?>
up
55
megan at voices dot com
4 years ago
As noted, list() will give an error if the input array is too short. This can be avoided by array_merge()'ing in some default values. For example:

<?php
$parameter
= 'name';
list(
$a, $b ) = array_merge( explode( '=', $parameter ), array( true ) );
?>

However, you will have to array_merge with an array long enough to ensure there are enough elements (if $parameter is empty, the code above would still error).

An alternate approach would be to use array_pad on the array to ensure its length (if all the defaults you need to add are the same).

<?php
    $parameter
= 'bob-12345';
    list(
$name, $id, $fav_color, $age ) = array_pad( explode( '-', $parameter ), 4, '' );
   
var_dump($name, $id, $fav_color, $age);
/* outputs
string(3) "bob"
string(5) "12345"
string(0) ""
string(0) ""
*/
?>
up
24
carlosv775 at gmail dot com
1 year ago
In PHP 7.1 we can do the following:

<?php
   
[$a, $b, $c] = ['a', 'b', 'c'];
?>

Before, we had to do:

<?php
   
list($a, $b, $c) = ['a', 'b''c'];
?>
up
45
svennd
5 years ago
The list() definition won't throw an error if your array is longer then defined list.
<?php

list($a, $b, $c) = array("a", "b", "c", "d");

var_dump($a); // a
var_dump($b); // b
var_dump($c); // c
?>
up
23
pemapmodder1970 at gmail dot com
2 years ago
list() can be used with foreach

<?php
$array
= [[1, 2], [3, 4], [5, 6]];

foreach(
$array as list($odd, $even)){
    echo
"$odd is odd; $even is even", PHP_EOL;
}
?>

The output:
===
1 is odd; 2 is even
3 is odd; 4 is even
5 is odd; 6 is even
up
14
john at jbwalker dot com
4 years ago
The list construct seems to look for a sequential list of indexes rather taking elements in sequence. What that obscure statement means is that if you unset an element, list will not simply jump to the next element and assign that to the variable but will treat the missing element as a null or empty variable:

    $test = array("a","b","c","d");
    unset($test[1]);
    list($a,$b,$c)=$test;
    print "\$a='$a' \$b='$b' \$c='$c'<BR>";

results in:
$a='a' $b='' $c='c'

not:
$a='a' $b='c' $c='d'
up
1
contato at tobias dot ws
3 months ago
Since PHP 7.1 the [] may now be used as an alternative to the existing list() syntax:

<?php
[$number, $message] = explode('|', '123|Hello World!');
?>
up
2
blazej
10 months ago
From PHP Version 7.1 you can specify keys in list(), or its new shorthand [] syntax. This enables destructuring of arrays with non-integer or non-sequential keys.

<?php
$data
= [
    [
"id" => 1, "name" => 'Tom'],
    [
"id" => 2, "name" => 'Fred'],
];

// list() style
list("id" => $id1, "name" => $name1) = $data[0];

// [] style
["id" => $id1, "name" => $name1] = $data[0];

// list() style
foreach ($data as list("id" => $id, "name" => $name)) {
   
// logic here with $id and $name
}

// [] style
foreach ($data as ["id" => $id, "name" => $name]) {
   
// logic here with $id and $name
}
up
3
anthony dot ossent at live dot fr
1 year ago
a simple example of use to swap two variables :

$a = 'hello';
$b = 'world';

list($a, $b) = [$b, $a];

echo $a . ' ' . $b; //display "world hello"

another example :

function getPosition($x, $y, $z)
{
   // ... some operations like $x++...
   return [$x, $y, $z];
}

list($x, $y, $z) = getPosition($x ,$y, $z);
up
3
Colin Guthrie
3 years ago
If you want use the undefined behaviour as you might expect it e.g. if you want:

  $b = ['a','b']; list($a, $b) = $b;

to result in $a=='a' and $b=='b', then you can just cast $b to an array (even although it already is) to create a copy. e.g.

  $b = ['a','b']; list($a, $b) = (array)$b;

and get the expected results.
up
4
Dean
2 years ago
UNDOCUMENTED BEHAVIOR:

    list($a,$b,$c) = null;

in fact works like:

    $a = null; $b = null; $c = null;

...So correspondingly:

    list($rows[]) = null;

Will increment count($rows), just as if you had executed $rows[] = null;

Watch out for this (for example) when retrieving entire tables from a database, e.g.

    while (list($rows[]) = $mysqlresult->fetch_row());

This will leave an extra 'null' entry as the last element of $rows.
up
0
Mardaneus
5 days ago
Unless you specify keys when using list() it expects the array being fed into it to start at 0.

So having the following code will result in a notice level warning "Undefined offset: 0" and variables not filling as expected

<?php
list($c1, $c2, $c3) = array [1 =>'a', 2 => 'b', 3 => 'c'];

var_dump($c1); // NULL
var_dump($c2); // string(1) "a"
var_dump($c3); // string(1) "b"

?>
up
0
petru at fuxspam dot xtremeweb dot ro
3 months ago
This is something I haven't seen in documentation.

Since PHP 7.1, you can use short-hand list unpacking using square brackets, just like short-hand array declaration:

<?php

$foo
= ['a', 'b', 'c'];

// short-hand array definition
[$a, $b, $c] = $foo;
echo
$a; // displays "a"

// it's same like:
list($x, $y, $z) = $foo;
echo
$x; // displays "a"

?>
To Top