​x
 
<!DOCTYPE html>
<html>
<body>
​
<?php
// 创建一个迭代器
class MyIterator implements Iterator {
  private $items = [];
  private $pointer = 0;
​
  public function __construct($items) {
    // array_values() 确保键是数字
    $this->items = array_values($items);
  }
​
  public function current() {
    return $this->items[$this->pointer];
  }
​
  public function key() {
    return $this->pointer;
  }
​
  public function next() {
    $this->pointer++;
  }
​
  public function rewind() {
    $this->pointer = 0;
  }
​
  public function valid() {
    // count() 表示列表中有多少项
    return $this->pointer < count($this->items);
  }
}
​
// 一个使用可迭代对象的函数
function printIterable(iterable $myIterable) {
  foreach($myIterable as $item) {
    echo $item;
  }
}
​
// 将迭代器用作可迭代对象
$iterator = new MyIterator(["a", "b", "c"]);
printIterable($iterator);
?>
​
</body>
</html>