PHP - Iterator接口的解释_iterator arrayaccess countable-优快云博客

本文介绍 PHP 中 Iterator 接口的基本定义及其实现方式，并通过一个具体示例展示了如何使用 Iterator 来遍历数组，同时解释了 rewind、current、key、next 和 valid 方法的作用。

Iterator的接口定义如下：

Iterator extends Traversable { abstract public mixed current ( void ) abstract public scalar key ( void ) abstract public void next ( void ) abstract public void rewind ( void ) abstract public boolean valid ( void ) }

下面是一个简单的例子演示Iterator的使用方法：

<?php class myIterator implements Iterator { private $position = 0; private $array = array( "firstelement", "secondelement", "lastelement", ); public function __construct() { $this->position = 0; } function rewind() { var_dump(__METHOD__); $this->position = 0; } function current() { var_dump(__METHOD__); return $this->array[$this->position]; } function key() { var_dump(__METHOD__); return $this->position; } function next() { var_dump(__METHOD__); ++$this->position; } 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"; } ?>

上面的例子会产生如下的输出：

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"