Опис

list(mixed $var, mixed ...$vars = ?): 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. Only arrays and objects that implement ArrayAccess can be unpacked. list() expressions can not be completely empty.

Зауваження:
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.

Зауваження:
Attempting to access an array key which has not been defined is the same as accessing any other undefined variable: an E_WARNING-level error message (E_NOTICE-level prior to PHP 8.0.0) will be issued, and the result will be null.

Attempting to unpack a scalar assigns null to all variables. Attempting to unpack an object that does not implement ArrayAccess is a fatal error.

Параметри

var: A variable.

vars: Further variables.

Значення, що повертаються

Returns the assigned array.

Журнал змін

Версія Опис

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.

Версія	Опис
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.

Приклади

Приклад #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
?>

Приклад #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";
}
?>

Приклад #3 Using nested list()

<?php

list($a, list($b, $c)) = array(1, array(2, 3));

var_dump($a, $b, $c);

?>

Поданий вище приклад виведе:

int(1)
int(2)
int(3)

The order in which the indices of the array to be consumed by list() are defined is irrelevant.

Приклад #4 list() and order of index definitions

<?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"

Приклад #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";

Поданий вище приклад виведе:

id: 1, name: Tom
id: 2, name: Fred

2, 4

Прогляньте також

each() - Return the current key and value pair from an array and advance the array cursor
array() - Create an array
extract() - Import variables into the current symbol table from an array