Detailed explanation of PHP iterators and how to use iteration

This time I will bring you a detailed explanation of PHP iterators and how to use iterations. What are the precautions when using PHP iterators and iterations? Here are practical cases, let’s take a look.

PHP's Object-oriented engine provides a very smart feature, that is, you can use the foreach() method to take out all the properties of an object through a loop. Like the array method, the code is as follows:

class Myclass{
  public $a = 'php';
  public $b = 'onethink';
  public $c = 'thinkphp';
}
$myclass = new Myclass();
//用foreach()将对象的属性循环出来
foreach($myclass as $key.'=>'.$val){
  echo &#39;$&#39;.$key.&#39; = &#39;.$val."<br/>";
}
/*返回
  $a = php
  $b = onethink
  $c = thinkphp
*/

If you need to implement more complex behavior, you can achieve it through an iterator (iterator)

//迭代器接口
interface MyIterator{
  //函数将内部指针设置回数据开始处
  function rewind();
  //函数将判断数据指针的当前位置是否还存在更多数据
  function valid();
  //函数将返回数据指针的值
  function key();
  //函数将返回将返回当前数据指针的值
  function value();
  //函数在数据中移动数据指针的位置
  function next();
}
//迭代器类
class ObjectIterator implements MyIterator{
  private $obj;//对象
  private $count;//数据元素的数量
  private $current;//当前指针
  function construct($obj){
    $this->obj = $obj;
    $this->count = count($this->obj->data);
  }
  function rewind(){
    $this->current = 0;
  }
  function valid(){
    return $this->current < $this->count;
  }
  function key(){
    return $this->current;
  }
  function value(){
    return $this->obj->data[$this->current];
  }
  function next(){
    $this->current++;
  }
}
interface MyAggregate{
  //获取迭代器
  function getIterator();
}
class MyObject implements MyAggregate{
  public $data = array();
  function construct($in){
    $this->data = $in;
  }
  function getIterator(){
    return new ObjectIterator($this);
  }
}
//迭代器的用法
$arr = array(2,4,6,8,10);
$myobject = new MyObject($arr);
$myiterator = $myobject->getIterator();
for($myiterator->rewind();$myiterator->valid();$myiterator->next()){
  $key = $myiterator->key();
  $value = $myiterator->value();
  echo $key.&#39;=>&#39;.$value;
  echo "<br/>";
}
/*返回
  0=>2
  1=>4
  2=>6
  3=>8
  4=>10
*/

I believe you have read this article You have mastered the case method. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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