static void Main(string[] args)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();     //開(kāi)始計(jì)時(shí)
            WebClient wc = new WebClient();
            string str = wc.DownloadString("http://www.jmeii.com/");
            Console.WriteLine(sw.IsRunning);    //輸出 true   計(jì)時(shí)器是否在運(yùn)行。
            sw.Stop();      //計(jì)時(shí)結(jié)束
            Console.WriteLine(sw.Elapsed);      //輸出 00:00:00.3452873
            Console.WriteLine(sw.ElapsedMilliseconds);  //輸出 223
            Console.WriteLine(sw.ElapsedTicks); //輸出501838
            Console.WriteLine(sw.IsRunning);    //輸出 flase

            Console.WriteLine(Stopwatch.GetTimestamp());   //輸出56151531319  獲取計(jì)時(shí)器機(jī)制中的當(dāng)前最小時(shí)間單位數(shù)。

            sw.Reset(); //重置
            Console.WriteLine(sw.Elapsed.ToString());   //輸出 00:00:00   //返回的是TimeSpan類型，可以任意處理

            sw.Restart();   //重新開(kāi)始
            FileStream fs = new FileStream(@"D:\admin_b.txt", FileMode.Open, FileAccess.Read);
            //string str = 
            byte[] byteArr = new byte[fs.Length];
            fs.Read(byteArr, 0, (int)fs.Length);
            Stopwatch sw2 = Stopwatch.StartNew();       //創(chuàng)建一個(gè)新的計(jì)時(shí)器
            string str2 = Encoding.UTF8.GetString(byteArr);
            sw.Stop();
            Console.WriteLine(sw.ElapsedMilliseconds);  //輸出 10
            Console.WriteLine(sw2.ElapsedMilliseconds); //輸出 9
            sw2.Stop();
            
            Console.ReadKey();
        }

static void Main(string[] args)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();
            FileStream fs = new FileStream(@"D:\admin_b.txt", FileMode.Open, FileAccess.Read);
            //string str = 
            byte[] byteArr = new byte[fs.Length];
            fs.Read(byteArr, 0, (int)fs.Length);
            string str = Encoding.UTF8.GetString(byteArr);
            sw.Stop();
            Console.WriteLine(sw.ElapsedMilliseconds);  //輸出 12

            Stopwatch sw2 = new Stopwatch();
            sw2.Start();
            File.ReadAllText(@"E:\admin_b.txt");
            sw2.Stop();
            Console.WriteLine(sw2.ElapsedMilliseconds); //輸出 11

            Console.ReadKey();
        }

public class Program
    {
        static void Main(string[] args)
        {
            //獲取到一個(gè)隨機(jī)數(shù)集合
            List<int> ListInt = new List<int>();
            Random r = new Random();
            for (int i = 0; i < 1000000; i++)       //生成一個(gè)1百萬(wàn)數(shù)字的集合
            {
                ListInt.Add(r.Next(1000));
            }

            Stopwatch sw = new Stopwatch();
            sw.Start();
            int count = 0;
            foreach (var i in ListInt)
            {
                count = count + i;          
            }
            Console.WriteLine("遍歷計(jì)算結(jié)果：" + count);       
            sw.Stop();
            Console.WriteLine("遍歷用時(shí)：" + sw.ElapsedMilliseconds);    //輸出 13

            Stopwatch sw2 = new Stopwatch();
            sw2.Start();
            int count2 = 0;
            count2 = ListInt.Sum();
            Console.WriteLine("Linq的計(jì)算結(jié)果：" + count2);
            Console.WriteLine("Linq的使用時(shí)間：" + sw2.ElapsedMilliseconds);  //輸出 12
            sw2.Stop();

            Console.ReadKey();
        }
    }