PHP yield作用

 生成器配合迭代器某些场景大大减少了内存消耗

 public function da()
    {
       for($i=0;$i<100000;$i++){
           yield $i;
       }
    }

    public function cs()
    {
        $data = [];
        for($i=0;$i<100000;$i++){
            $data[] =  $i;
        }
        return $data;
    }
    public function index()
    {
        $data = $this->cs();
        foreach ($data as $val){
            echo $val.'<br />';
        }
        echo "初始: ".memory_get_usage()."B\n";
        $str = str_repeat('hello', 1000);
        echo "使用: ".memory_get_usage()."B\n";
        unset($str);
        echo "释放: ".memory_get_usage()."B\n";
        echo "峰值: ".memory_get_peak_usage()."B\n";
    }
    ![在这里插入图片描述](https://img-blog.csdnimg.cn/20201210111826889.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NTX19Mb3Zl,size_16,color_FFFFFF,t_70#pic_center)
    ![在这里插入图片描述](https://img-blog.csdnimg.cn/20201210111853280.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NTX19Mb3Zl,size_16,color_FFFFFF,t_70#pic_center)