PHP对象迭代
介绍
从PHP5开始，可以遍历对象的所有可见项的列表。可以使用foreach循环以及迭代器接口来执行迭代。PHP中还有IteratorAggregate接口，可用于此目的
使用foreach循环
示例
<?php
class myclass{
private $var;
protected $var1;
public $x, $y, $z;
public function __construct(){
$this->var="private variable";
$this->var1=TRUE;
$this->x=100;
$this->y=200;
$this->z=300;
}
public function iterate(){
foreach ($this as $key => $value) {
print "$key => $value\n";
}
}
}
$obj = new myclass();
foreach($obj as $key => $value) {
print "$key => $value\n";
}
echo "\n";
$obj->iterate();
?>输出结果
输出如下-
x => 100 y => 200 z => 300 var => private variable var1 => 1 x => 100 y => 200 z => 300
使用迭代器接口
此接口定义以下抽象方法，在以下示例中将实现
abstract public current ( void ) : mixed abstract public key ( void ) : scalar abstract public next ( void ) : void abstract public rewind ( void ) : void abstract public valid ( void ) : bool
Iterator::current—返回当前元素
Iterator::key—返回当前元素的键
Iterator::next-移至下一个元素
Iterator::rewind—将Iterator倒退到第一个元素
Iterator::valid—检查当前位置是否有效
以下示例通过实现Iterator接口演示了对象迭代
示例
<?php
class myclass implements Iterator{
private $arr = array('a','b','c');
public function rewind(){
echo "rewinding\n";
reset($this->arr);
}
public function current(){
$var = current($this->arr);
echo "current: $var\n";
return $var;
}
public function key() {
$var = key($this->arr);
echo "key: $var\n";
return $var;
}
public function next() {
$var = next($this->arr);
echo "next: $var\n";
return $var;
}
public function valid(){
$key = key($this->arr);
$var = ($key !== NULL && $key !== FALSE);
echo "valid: $var\n";
return $var;
}
}
$obj = new myclass();
foreach ($obj as $k => $v) {
print "$k: $v\n";
}
?>输出结果
上面的代码产生以下结果-
rewinding valid: 1 current: a key: 0 0: a next: b valid: 1 current: b key: 1 1: b next: c valid: 1 current: c key: 2 2: c next: valid: