PHP 5 提供了一种定义对象的方法使其可以通过单元列表来遍历，例如用 foreach 语句。默认情况下，所有可见属性都将被用于遍历。
Example #1 简单的对象遍历
class MyClass{ public $var1 = 1; public $var2 = 2; public $var3 = 3; protected $protected = 'protected var'; private $private = 'private var'; function iterateVisible(){ echo "MyClass::iterateVisible:<br>"; foreach($this as $key => $value){ print "$key=>$value<br>"; } }} $class = new MyClass();foreach($class as $key => $value){ print <strong style="color:transparent">来2源gaodaima#com搞(代@码&网</strong><label>搞gaodaima代码</label>"$key => $value<br>";}echo "<br>";$class->iterateVisible();
输出结果：
var1 => 1
var2 => 2
var3 => 3
MyClass::iterateVisible:
var1=>1
var2=>2
var3=>3
protected=>protected var
private=>private var
如上所示，foreach 遍历了所有其能够访问的可见属性。
更进一步，可以实现 Iterator接口。可以让对象自行决定如何遍历以及每次遍历时那些值可用。
class MyIterator implements Iterator{ private $var = array(); public function __construct($array) { if(is_array($array)){ $this->var = $array; } } public function rewind(){ echo "rewinding<br>"; reset($this->var); } public function current(){ $var = current($this->var); echo "current:$var<br>"; return $var; } public function key(){ $var = key($this->var); echo "key:$var<br>"; return $var; } public function next(){ $var = next($this->var); echo "next:$var<br>"; return $var; } public function valid(){ $var = $this->current()!==false; echo "valid:$var<br>"; return $var; }}$values = array(1,2,3);$it = new MyIterator($values);foreach($it as $a => $b){ print "$a:$b<br>";}
输出结果：
rewinding
current:1
valid:1
current:1
key:0
0:1
next:2
current:2
valid:1
current:2
key:1
1:2
next:3
current:3
valid:1
current:3
key:2
2:3
next:
current:
valid:
可以用 IteratorAggregate接口以替代实现所有的 Iterator 方法。IteratorAggregate 只需要实现一个方法 IteratorAggregate::getIterator()，其应返回一个实现了 Iterator 的类的实例。
Example #3 通过实现 IteratorAggregate 来遍历对象
include_once('class2.php');class MyCollection implements IteratorAggregate{ private $items = array(); private $count = 0; public function getIterator(){ return new MyIterator($this->items); } public function add($value){ $this->items[$this->count++] = $value; }}$coll = new MyCollection();$coll -> add('1');$coll -> add('2');$coll -> add('3');foreach($coll as $k => $v){ echo "key/value:[$k->$v]<br><br>";}
输出结果：
rewinding
current:1
valid:1
current:1
key:0
key/value:[0->1]
next:2
current:2
valid:1
current:2
key:1
key/value:[1->2]
next:3
current:3
valid:1
current:3
key:2
key/value:[2->3]
next:
current:
valid:
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