int tnum = 100000; // 添加或查找的次数
int outnum = 10; // 外层循环次数

List<string> arr = new List<string>();
for(int i=0;i<tnum;i++)
    arr.Add(i.ToString());
string[] arr2 = new string[tnum];

for(int j=0;j<outnum;j++)
{
    Stopwatch watch = new Stopwatch();
    string msg;

    msg = "Number ";
    watch.Reset();
    watch.Start();
    for (int i = 0, h = arr.Count; i < h; i++)
    {
    }
    watch.Stop();
    Console.WriteLine(msg + "耗时:" + watch.ElapsedTicks.ToString());

    msg = ".Count ";
    watch.Reset();
    watch.Start();
    for (int i = 0; i < arr.Count; i++)
    {
    }
    watch.Stop();
    Console.WriteLine(msg + "耗时:" + watch.ElapsedTicks.ToString());

    msg = "Length ";
    watch.Reset();
    watch.Start();
    for (int i = 0; i < arr2.Length; i++)
    {
    }
    watch.Stop();
    Console.WriteLine(msg + "耗时:" + watch.ElapsedTicks.ToString());
}