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可在内部迭代自己的外部迭代器或类的接口。
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 boolean valid(void)
}举个栗子，定义一个迭代器：
class myIerator implements Iterator
{
protected $position;//指针
public $arr = [];
public function __construct(array $arr)
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
$this->arr = $arr;
return $this;
}
//获取当前的值
public function current()
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
return $this->arr[$this->position] ?? null;
}
//将指针移至下一位
public function next()
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
return ++$this->position;
}
//返回当前的指针
public function key()
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
return $this->position;
}
//重置指针
public function rewind()
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
$this->position = 0;
}
//检查当前是否有效
public function valid()
{
$info = date('Y-m-d H:i:s') . ' ' . __METHOD__ . ' Line :' . __LINE__ . "\r\n";
$this->writeLog($info);
return isset($this->arr[$this->position]);
}
private function writeLog(string $info)
{
error_log($info, 3, './debug.log');
}
}$zhangsan=['one','two','three','four'];
$arr = new myIerator($zhangsan);
foreach ($arr as $k => $v) {
echo "{$k} => {$v} \r\n";
}打印结果：
0 => one
1 => two
2 => three
3 => four
查看调用日志：
2017-11-27 15:56:04 myIerator::__construct Line :16
2017-11-27 15:56:04 myIerator::rewind Line :50 重置指针
2017-11-27 15:56:04 myIerator::valid Line :58 校验是否有效
2017-11-27 15:56:04 myIerator::current Line :25 获取当前指针的值
2017-11-27 15:56:04 myIerator::key Line :41 获取当前指针位置
2017-11-27 15:56:04 myIerator::next Line :33 指针下移一位（进入下一个循环）
2017-11-27 15:56:04 myIerator::valid Line :58
2017-11-27 15:56:04 myIerator::current Line :25
2017-11-27 15:56:04 myIerator::key Line :41
2017-11-27 15:56:04 myIerator::next Line :33
2017-11-27 15:56:04 myIerator::valid Line :58
2017-11-27 15:56:04 myIerator::current Line :25
2017-11-27 15:56:04 myIerator::key Line :41
2017-11-27 15:56:04 myIerator::next Line :33
2017-11-27 15:56:04 myIerator::valid Line :58
2017-11-27 15:56:04 myIerator::current Line :25
2017-11-27 15:56:04 myIerator::key Line :41
2017-11-27 15:56:04 myIerator::next Line :33
2017-11-27 15:56:04 myIerator::valid Line :58
//遍历方式二：
$arr->rewind();
while($arr->valid()) {
$key=$arr->key();
$value=$arr->current();
echo"{$key} =>{$value}\r";
$arr->next();
}
网页标题：PHP迭代器Iterator接口
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