[php predefined interface] iterator

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Iterator (Iterator) Interface

Introduction: An interface that can internally iterate its own external iterator or class.

Explanation of specific functions

Interface summary:

Iterator extends Traversable {    /* 方法 */
    abstract public mixed current ( void )    abstract public scalar key ( void )    abstract public void next ( void )    abstract public void rewind ( void )    abstract public bool valid ( void )
}

Example:

Example #1 基本用法（使用 foreach 时，迭代器方法的调用顺序）<?phpclass 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 "\n";
}1.rewind -> valid -> current -> key 
2.next -> valid -> current -> key3.next -> valid -> current -> key4.next -> valid?>

         

Iterator (Iterator) interface

Introduction: An interface that can internally iterate its own external iterator or class.

Explanation of specific functions

Interface summary:

Iterator extends Traversable {    /* 方法 */
    abstract public mixed current ( void )    abstract public scalar key ( void )    abstract public void next ( void )    abstract public void rewind ( void )    abstract public bool valid ( void )
}

Example:

Example #1 基本用法（使用 foreach 时，迭代器方法的调用顺序）<?phpclass 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 "\n";
}1.rewind -> valid -> current -> key 
2.next -> valid -> current -> key3.next -> valid -> current -> key4.next -> valid?>

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