The Iterator interface

The Iterator interface

Introduction

(PHP 5, PHP 7, PHP 8)

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.

<?php
class myIterator implements Iterator {
    private $position = 0;
    private $array = array(
        "firstelement",
        "secondelement",
        "lastelement",
    );  

    public function __construct() {
        $this->position = 0;
    }

    public function rewind() {
        var_dump(__METHOD__);
        $this->position = 0;
    }

    public function current() {
        var_dump(__METHOD__);
        return $this->array[$this->position];
    }

    public function key() {
        var_dump(__METHOD__);
        return $this->position;
    }

    public function next() {
        var_dump(__METHOD__);
        ++$this->position;
    }

    public function valid() {
        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

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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/class.iterator.php