iterator_to_array

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

iterator_to_array — Copy the iterator into an array

Description

iterator_to_array(Traversable|array $iterator, bool $preserve_keys = true): array

Copy the elements of an iterator into an array.

Parameters

iterator

The iterator being copied.

preserve_keys

Whether to use the iterator element keys as index.

If a key is an array or object, a warning will be generated. null keys will be converted to an empty string, float keys will be truncated to their int counterpart, resource keys will generate a warning and be converted to their resource ID, and bool keys will be converted to integers.

Note:
If this parameter is not set or set to true, duplicate keys will be overwritten. The last value with a given key will be in the returned array. Set this parameter to false to get all the values in any case.

Return Values

An array containing the elements of the iterator.

Changelog

Version	Description
8.2.0	The type of `iterator` has been widened from Traversable to Traversable\|array.

Examples

Example #1 iterator_to_array() example

<?php
$iterator = new ArrayIterator(array('recipe'=>'pancakes', 'egg', 'milk', 'flour'));
var_dump(iterator_to_array($iterator, true));
var_dump(iterator_to_array($iterator, false));
?>

The above example will output:

array(4) {
  ["recipe"]=>
  string(8) "pancakes"
  [0]=>
  string(3) "egg"
  [1]=>
  string(4) "milk"
  [2]=>
  string(5) "flour"
}
array(4) {
  [0]=>
  string(8) "pancakes"
  [1]=>
  string(3) "egg"
  [2]=>
  string(4) "milk"
  [3]=>
  string(5) "flour"
}

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User Contributed Notes 4 notes

down

wizzard351 at yahoo dot com ¶

3 years ago

One important thing to remember is that in iterator can be infinite. Not all iterators necessarily end. If iterator_to_array is used on such an iterator, it will exhaust the available memory, and throw a fatal error.

For example, consider the following code:

<?php

function fibonacci(): Generator
{
    yield $a = 1;
    yield $b = 2;

    start:
    yield $c = $a + $b;
    $a = $b;
    $b = $c;
    goto start;
}

$fibonacciSequence = fibonacci();
iterator_to_array($fibonacciSequence);

?>

Since <?php fibonacci(); ?> generates an infinite fibonacci sequence, which is valid, since it is actually an infinite sequence, then attempting to convert it to an array will fail.

down

jerome at yazo dot net ¶

16 years ago

Using the boolean param :



<?php



$first = new ArrayIterator( array('k1' => 'a' , 'k2' => 'b',  'k3' => 'c',  'k4' => 'd') );

$second = new ArrayIterator( array( 'k1' => 'X', 'k2' => 'Y', 'Z' ) );



$combinedIterator= new AppendIterator();

$combinedIterator->append( $first );

$combinedIterator->append( $second );



var_dump( iterator_to_array($combinedIterator, false) );



?>



will output : 



array(7) (

  [0]=>

  string(1) "a"

  [1]=>

  string(1) "b"

  [2]=>

  string(1) "c"

  [3]=>

  string(1) "d"

  [4]=>

  string(1) "X"

  [5]=>

  string(1) "Y"

  [6]=>

  string(1) "Z"

)



<?php



var_dump( iterator_to_array($combinedIterator, true) );



?>



will output (since keys would merge) :



array(5) (

  ["k1"]=>

  string(1) "X"

  ["k2"]=>

  string(1) "Y"

  ["k3"]=>

  string(1) "c"

  ["k4"]=>

  string(1) "d"

  [0]=>

  string(1) "Z"

)

down

joksnet at gmail dot com ¶

11 years ago

To generate an deep array from nested iterators:

<?php
function iterator_to_array_deep(\Traversable $iterator, $use_keys = true) {
    $array = array();
    foreach ($iterator as $key => $value) {
        if ($value instanceof \Iterator) {
            $value = iterator_to_array_deep($value, $use_keys);
        }
        if ($use_keys) {
            $array[$key] = $value;
        } else {
            $array[] = $value;
        }
    }
    return $array;
}
?>

I use it to test an iterator: https://gist.github.com/jm42/cb328106f393eeb28751

down

Harry Willis ¶

10 years ago

When using iterator_to_array() on an SplObjectStorage object, it's advisable to set $use_keys to false.

The resulting array is identical, since the iterator keys produced by SplObjectStorage::key() are always integers from 0 to (COUNT-1). Passing $use_keys=false cuts out the unnecessary calls to SplObjectStorage::key(), giving a slight performance advantage.

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