(PHP 4, PHP 5, PHP 7, PHP 8)
list — Assign variables as if they were an array
Like array(), this is not really a function, but a language construct. list() is used to assign a list of variables in one operation. Strings can not be unpacked and list() expressions can not be completely empty.
Note:
Before PHP 7.1.0, list() only worked on numerical arrays and assumes the numerical indices start at 0.
As of PHP 7.1.0, list() can also contain explicit keys, allowing for the destructuring of arrays with non-integer or non-sequential keys. For more details on array destructuring, see the array destructuring section.
varA variable.
varsFurther variables.
Returns the assigned array.
| Version | Description |
|---|---|
| 7.3.0 | Support for reference assignments in array destructuring was added. |
| 7.1.0 | It is now possible to specify keys in list(). This enables destructuring of arrays with non-integer or non-sequential keys. |
Example #1 list() examples
<?php
$info = array('coffee', 'brown', 'caffeine');
// Listing all the variables
list($drink, $color, $power) = $info;
echo "$drink is $color and $power makes it special.\n";
// Listing some of them
list($drink, , $power) = $info;
echo "$drink has $power.\n";
// Or let's skip to only the third one
list( , , $power) = $info;
echo "I need $power!\n";
// list() doesn't work with strings
list($bar) = "abcde";
var_dump($bar); // NULL
?>
Example #2 An example use of list()
<?php
$result = $pdo->query("SELECT id, name FROM employees");
while (list($id, $name) = $result->fetch(PDO::FETCH_NUM)) {
echo "id: $id, name: $name\n";
}
?>
Example #3 Using nested list()
<?php
list($a, list($b, $c)) = array(1, array(2, 3));
var_dump($a, $b, $c);
?>int(1) int(2) int(3)
Example #4 list() and order of index definitions
The order in which the indices of the array to be consumed by list() are defined is irrelevant.
<?php
$foo = array(2 => 'a', 'foo' => 'b', 0 => 'c');
$foo[1] = 'd';
list($x, $y, $z) = $foo;
var_dump($foo, $x, $y, $z);Gives the following output (note the order of the elements compared in which order they were written in the list() syntax):
array(4) {
[2]=>
string(1) "a"
["foo"]=>
string(1) "b"
[0]=>
string(1) "c"
[1]=>
string(1) "d"
}
string(1) "c"
string(1) "d"
string(1) "a"
Example #5 list() with keys
As of PHP 7.1.0 list() can now also contain explicit keys, which can be given as arbitrary expressions. Mixing of integer and string keys is allowed; however, elements with and without keys cannot be mixed.
<?php
$data = [
["id" => 1, "name" => 'Tom'],
["id" => 2, "name" => 'Fred'],
];
foreach ($data as ["id" => $id, "name" => $name]) {
echo "id: $id, name: $name\n";
}
echo PHP_EOL;
list(1 => $second, 3 => $fourth) = [1, 2, 3, 4];
echo "$second, $fourth\n";The above example will output:
id: 1, name: Tom id: 2, name: Fred 2, 4