获取运行时间

System.Diagnostics.Stopwatch watch = new System.Diagnostics.Stopwatch();
watch.Start();//开始计时

for(int i=0,i<=50,i++){

　　Console.WriteLine($"第{i}遍打印");

}

watch.Stop();//停止计时
var time = watch.ElapsedMilliseconds;  //以毫秒为单位