list

(PHP 4, PHP 5, PHP 7)

listAssign variables as if they were an array


Description

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.

Note:

Before PHP 7.1.0, list() only worked on numerical arrays and assumes the numerical indices start at 0.

Warning In PHP 5, list() assigns the values starting with the right-most parameter. In PHP 7, list() starts with the left-most parameter.

If you are using plain variables, you don't have to worry about this. But if you are using arrays with indices you usually expect the order of the indices in the array the same you wrote in the list() from left to right, which is not the case in PHP 5, as it's assigned in the reverse order.

Generally speaking, it is advisable to avoid relying on a specific order of operation, as this may change again in the future.


Parameters

var
A variable.
vars
Further variables.


Return Values

Returns the assigned array.


Changelog

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.

7.0.0 The order that the assignment operations are performed in has

changed.

7.0.0 list() expressions can no longer be completely

empty.

7.0.0 Strings can no longer be unpacked.


Examples

Example #1 list() examples

<?php$info = array('coffee', 'brown', 'caffeine');// Listing all the variableslist($drink, $color, $power) = $info;echo "$drink is $color and $power makes it special.\n";// Listing some of themlist($drink, , $power) = $info;echo "$drink has $power.\n";// Or let's skip to only the third onelist( , , $power) = $info;echo "I need $power!\n";// list() doesn't work with stringslist($bar) = "abcde";var_dump($bar); // NULL?>

Example #2 An example use of list()

<table> <tr>  <th>Employee name</th>  <th>Salary</th> </tr><?php$result = $pdo->query("SELECT id, name, salary FROM employees");while (list($id, $name, $salary) = $result->fetch(PDO::FETCH_NUM)) {    echo " <tr>\n" .          "  <td><a href=\"info.php?id=$id\">$name</a></td>\n" .          "  <td>$salary</td>\n" .          " </tr>\n";}?></table>

Example #3 Using nested list()

<?phplist($a, list($b, $c)) = array(1, array(2, 3));var_dump($a, $b, $c);?>

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

Example #4 Using list() with array indices

<?php$info = array('coffee', 'brown', 'caffeine');list($a[0], $a[1], $a[2]) = $info;var_dump($a);?>

Gives the following output (note the order of the elements compared in which order they were written in the list() syntax):


Output of the above example in PHP 7:


array(3) {
  [0]=>
  string(6) "coffee"
  [1]=>
  string(5) "brown"
  [2]=>
  string(8) "caffeine"
}

Output of the above example in PHP 5:


array(3) {
  [2]=>
  string(8) "caffeine"
  [1]=>
  string(5) "brown"
  [0]=>
  string(6) "coffee"
}

Example #5 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 #6 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

See Also

  • 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