C#计算一段程序运行时间的三种方法

直接上代码：

第一种方法利用System.DateTime.Now

 "code" class="csharp">static void SubTest()
 {
     DateTime beforDT = System.DateTime.Now;

     //耗时巨大的代码

     DateTime afterDT = System.DateTime.Now;
     TimeSpan ts = afterDT.Subtract(beforDT);
     Console.WriteLine("DateTime总共花费{0}ms.", ts.TotalMilliseconds);
 }

 第二种方法

 static void SubTest()
 {
 "white-space:pre">    Stopwatch sw = new Stopwatch();
 "white-space:pre">    sw.Start();

 "white-space:pre">    //耗时巨大的代码
 "white-space:pre">
 "white-space:pre">    sw.Stop();
 "white-space:pre">    TimeSpan ts2 = sw.Elapsed;
 "white-space:pre">    Console.WriteLine("Stopwatch总共花费{0}ms.", ts2.TotalMilliseconds);
 }

 第三种方法

 [System.Runtime.InteropServices.DllImport("Kernel32.dll")]
 static extern bool QueryPerformanceCounter(ref long count);
 [System.Runtime.InteropServices.DllImport("Kernel32.dll")]
 static extern bool QueryPerformanceFrequency(ref long count);
 static void SubTest()
 {
 "white-space:pre">    long count = 0;
 "white-space:pre">    long count1 = 0;
 "white-space:pre">    long freq = 0;
 "white-space:pre">    double result = 0;
 "white-space:pre">    QueryPerformanceFrequency(ref freq);
 "white-space:pre">    QueryPerformanceCounter(ref count);


 "white-space:pre">    //耗时巨大的代码
 "white-space:pre">
 "white-space:pre">    QueryPerformanceCounter(ref count1);
 "white-space:pre">    count = count1 - count;
 "white-space:pre">    result = (double)(count) / (double)freq;
 "white-space:pre">    Console.WriteLine("QueryPerformanceCounter耗时: {0} 秒", result);
 }