The Iterator interface

- « Traversable

- Iterator::current »

- PHP Manual
- Predefined Interfaces and Classes
- The Iterator interface

# The Iterator interface

(PHP 5, PHP 7, PHP 8)

## Introduction

Interface for external iterators or objects that can be iterated themselves internally.

## Interface synopsis

interface Iterator extends Traversable {
/* Methods */
public current(): mixed
public key(): mixed
public next(): void
public rewind(): void
public valid(): bool
}

## Predefined iterators

PHP already provides a number of iterators for many day to day tasks. See SPL iterators for a list.

## Examples

Example #1 Basic usage

This example demonstrates in which order methods are called when using foreach with an iterator.

    <?phpclass myIterator implements Iterator {    private $position = 0;    private $array = array(        "firstelement",        "secondelement",        "lastelement",    );      public function __construct() {        $this->position = 0;    }    public function rewind(): void {        var_dump(__METHOD__);        $this->position = 0;    }    #[\ReturnTypeWillChange]    public function current() {        var_dump(__METHOD__);        return $this->array[$this->position];    }    #[\ReturnTypeWillChange]    public function key() {        var_dump(__METHOD__);        return $this->position;    }    public function next(): void {        var_dump(__METHOD__);        ++$this->position;    }    public function valid(): bool {        var_dump(__METHOD__);        return isset($this->array[$this->position]);    }}$it = new myIterator;foreach($it as $key => $value) {    var_dump($key, $value);    echo "\n";}?>

The above example will output something similar to:

    string(18) "myIterator::rewind"
    string(17) "myIterator::valid"
    string(19) "myIterator::current"
    string(15) "myIterator::key"
    int(0)
    string(12) "firstelement"

    string(16) "myIterator::next"
    string(17) "myIterator::valid"
    string(19) "myIterator::current"
    string(15) "myIterator::key"
    int(1)
    string(13) "secondelement"

    string(16) "myIterator::next"
    string(17) "myIterator::valid"
    string(19) "myIterator::current"
    string(15) "myIterator::key"
    int(2)
    string(11) "lastelement"

    string(16) "myIterator::next"
    string(17) "myIterator::valid"

## See Also

See also object iteration.

## Table of Contents

- Iterator::current — Return the current element
- Iterator::key — Return the key of the current element
- Iterator::next — Move forward to next element
- Iterator::rewind — Rewind the Iterator to the first element
- Iterator::valid — Checks if current position is valid