PHP

15468

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 "<br />";  
}  
?>   


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"


原文地址：http://blog.csdn.net/amonest/article/details/6193221