分享:PHP迭代器的内部执行过程

<?php
class myIterator implements Iterator {
    private $position = 0;
    private $array = array(
        "first_element",
        "second_element",
        "last_element",
    );
    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 => $value) {
 echo '输出键值：';
    var_dump($key, $value);
 //echo $key;
    echo "\n";
}

<?php
/**
* php迭代器
*  by www.jbxue.com
*/
class MyIterator implements Iterator
{
     private $var = array();
     public function __construct($array)
     {
         if (is_array($array)) {
            $this->var = $array;
         }
     }
     public function rewind() {
         echo "倒回第一个元素\n";
        reset($this->var);
     }
     public function current() {
        $var = current($this->var);
         echo "当前元素: $var\n";
         return $var;
     }
     public function key() {
        $var = key($this->var);
         echo "当前元素的键: $var\n";
         return $var;
     }
     public function next() {
        $var = next($this->var);
         echo "移向下一个元素: $var\n";
         return $var;
     }
     public function valid() {
        $var = $this->current() !== false;
         echo "检查有效性: {$var}\n";
         return $var;
     }
}
$values = array(1,2,3);
$it = new MyIterator($values);
foreach ($it as $k => $v) {
     print "此时键值对 -- key $k: value $v\n\n";
}