PHP 8.1.0 RC 2 available for testing

The ArrayIterator class

(PHP 5, PHP 7, PHP 8)

Introduction

This iterator allows to unset and modify values and keys while iterating over Arrays and Objects.

When you want to iterate over the same array multiple times you need to instantiate ArrayObject and let it create ArrayIterator instances that refer to it either by using foreach or by calling its getIterator() method manually.

Class synopsis

class ArrayIterator implements ArrayAccess, SeekableIterator, Countable, Serializable {
/* Constants */
const int STD_PROP_LIST = 1;
const int ARRAY_AS_PROPS = 2;
/* Methods */
public __construct(array|object $array = [], int $flags = 0)
public append(mixed $value): void
public asort(int $flags = SORT_REGULAR): bool
public count(): int
public current(): mixed
public getArrayCopy(): array
public getFlags(): int
public key(): mixed
public ksort(int $flags = SORT_REGULAR): bool
public natcasesort(): bool
public natsort(): bool
public next(): void
public offsetExists(mixed $key): bool
public offsetGet(mixed $key): mixed
public offsetSet(mixed $key, mixed $value): void
public offsetUnset(mixed $key): void
public rewind(): void
public seek(int $offset): void
public serialize(): string
public setFlags(int $flags): void
public uasort(callable $callback): bool
public uksort(callable $callback): bool
public unserialize(string $data): void
public valid(): bool
}

Predefined Constants

ArrayIterator Flags

ArrayIterator::STD_PROP_LIST

Properties of the object have their normal functionality when accessed as list (var_dump, foreach, etc.).

ArrayIterator::ARRAY_AS_PROPS

Entries can be accessed as properties (read and write).

Table of Contents

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User Contributed Notes 7 notes

up
44
Venelin Vulkov
12 years ago
Another fine Iterator from php . You can use it especially when you have to iterate over objects

<?php
$fruits
= array(
   
"apple" => "yummy",
   
"orange" => "ah ya, nice",
   
"grape" => "wow, I love it!",
   
"plum" => "nah, not me"
);
$obj = new ArrayObject( $fruits );
$it = $obj->getIterator();

// How many items are we iterating over?

echo "Iterating over: " . $obj->count() . " values\n";

// Iterate over the values in the ArrayObject:
while( $it->valid() )
{
    echo
$it->key() . "=" . $it->current() . "\n";
   
$it->next();
}

// The good thing here is that it can be iterated with foreach loop

foreach ($it as $key=>$val)
echo
$key.":".$val."\n";

/* Outputs something like */

Iterating over: 4 values
apple
=yummy
orange
=ah ya, nice
grape
=wow, I love it!
plum=nah, not me

?>

Regards.
up
18
Relakuyae
9 years ago
Need a callback on an iterated value, but don't have PHP 5.4+?  This makes is stupid easy:

<?php
class ArrayCallbackIterator extends ArrayIterator {
  private
$callback;
  public function
__construct($value, $callback) {
   
parent::__construct($value);
   
$this->callback = $callback;
  }

  public function
current() {
   
$value = parent::current();
    return
call_user_func($this->callback, $value);
  }
}
?>

You can use it pretty much exactly as the Array Iterator:

<?php
$iterator1
= new ArrayCallbackIterator($valueList, "callback_function");
$iterator2 = new ArrayCallbackIterator($valueList, array($object, "callback_class_method"));
?>
up
7
Sean Burlington
12 years ago
and to iterate recursively use the (sparsely documented)  RecursiveArrayIterator

<?php

$fruits
= array(
               
"apple" => "yummy",
               
"orange" => "ah ya, nice",
               
"grape" => "wow, I love it!",
                
"plum" => "nah, not me"
               
);

$veg = array("potato" => "chips", "carrot" => "soup");
$grocery = array($fruits, $veg);
$obj = new ArrayObject( $grocery );

$it = new RecursiveIteratorIterator( new RecursiveArrayIterator($grocery));

foreach (
$it as $key=>$val)
echo
$key.":".$val."\n";

?>

Output
--------
apple:yummy
orange:ah ya, nice
grape:wow, I love it!
plum:nah, not me
potato:chips
carrot:soup
up
1
mail at markuszeller dot com
6 months ago
I recommend using ArrayIterator() only in the IteratorAggregate interface on behalf of memory usage.
When not used in that context, the array will be copied on creating a new ArrayIterator().

<?php
class Data implements IteratorAggregate
{
    private array
$array = [];

    public function
__construct()
    {
        for (
$i = 0; $i < 1e5; $i++) $this->array[] = true;
    }

    public function
getIterator(): ArrayIterator
   
{
        return new
ArrayIterator($this->array);
    }
}

$data1 = new Data();
echo
memory_get_usage(), PHP_EOL;
// 4610240

foreach($data1 as $data) {}
echo
memory_get_usage(), PHP_EOL;
// 4610240

foreach($data1 as $data) {}
echo
memory_get_usage(), PHP_EOL;
// 4610240
?>

Memory usage still stay the same.
Now create it without the IteratorAggregate interface.

<?php
$agg
= [];
for (
$i = 0; $i < 1e5; $i++) $agg[] = true;
echo
memory_get_usage(), PHP_EOL;
// 8808720

$iterator1 = new ArrayIterator($agg);
echo
memory_get_usage(), PHP_EOL;
// 13007328

$iterator2 = new ArrayIterator($agg);
echo
memory_get_usage(), PHP_EOL;
// 17205936
?>
up
0
shaman_master at list dot ru
1 year ago
If you want something like `ArrayCallbackIterator` by Relakuyae https://www.php.net/manual/ru/class.arrayiterator.php#106231 , use function `iterator_apply`.
up
-9
daniel dot rutkoski at gmail dot com
5 years ago
<?php
class PrintArray
{
    private
$code = null;

    function
__construct ($val)
    {
       
$this->code = $val;
       
$this->_print();
    }
   
    private function
arrayIterator($val, $grau)
    {
       
$grau++;
       
$arr = new \ArrayIterator($val);
        while (
$arr->valid())
        {
            if(
is_array($arr->current()))
            {
               
$this->arrayIterator($arr->current(), $grau);
            }
            else
            {
               
$this->code .= str_repeat(" ", (4 * $grau)) . $arr->key() . " : " . $arr->current() . PHP_EOL;
            }
           
$arr->next();
        }
    }
   
    private function
_print()
    {
        if (
is_array($this->code))
        {
           
$arr = new \ArrayIterator($this->code);
           
$this->code = 'array(' . PHP_EOL;
            while (
$arr->valid())
            {
                if(
is_array($arr->current()))
                {
                   
$this->arrayIterator($arr->current(), 0);
                }
                else
                {
                   
$this->code .= $arr->key() . " : " . $arr->current() . "\n";
                }
               
$arr->next();
            }
           
$this->code .= ')';
        }
        return
$this;
    }
   
    public function
getVal ()
    {
        return
$this->code;
    }
}

$arr = array(
    array(
       
'ok' => 1, array(9,7,5,9,'a','b'=>array(1,2)),
       
'error' => 2, array('h','u','o')
    )
    ,
'array'
);
$pArray = new PrintArray($arr);
var_dump($pArray->getVal());
up
-28
foobuilder at gmail dot com
10 years ago
Unsetting all keys of an ArrayItem within foreach will always leave the second key:

<?php
$items
= new ArrayObject(range(0, 9));

while (list(
$k, $v) = each($items)) {
    unset(
$items[$k]);
}

print_r($items);

//  ArrayIterator Object
//  (
//      [storage:ArrayIterator:private] => Array
//          (
//              [1] => 1
//          )
//  )
?>

I'm not sure if this is a bug as unsetting keys within foreach is usually a bad idea to begin with (use while instead), but it's something to be aware of.
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