C#计算一段程序运行时间的三种方法

直接代码：
第一种方法利用System.DateTime.Now

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);
}

 1         public static void SubTest()
 2         {
 3             DateTime beforeDT = System.DateTime.Now;
 4             int[] a = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
 5             //Shuffle(a) is the function you want to test.
 6             Shuffle(a);
 7             DateTime afterDT = System.DateTime.Now;
 8             TimeSpan ts = afterDT.Subtract(beforeDT);
 9             Console.WriteLine("DateTime costed for Shuffle function is: {0}ms",ts.TotalMilliseconds);
10         }

第二种用Stopwatch类(System.Diagnostics)

 1         public static void SubTest()
 2         {
 3             Stopwatch sw = new Stopwatch();
 4             sw.Start();
 5             //Shuffle(a) is the function you want to test.
 6             int[] a = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
 7             Shuffle(a);
 8             sw.Stop();
 9             TimeSpan ts = sw.Elapsed;
10             Console.WriteLine("DateTime costed for Shuffle function is: {0}ms", ts.TotalMilliseconds);
11         }

 

第三种用API实现：个人感觉以秒为单位来计算程序耗时，数量级有点大了，还是推荐前面两种毫秒级别的……

[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()
{
    long count = 0;
    long count1 = 0;
    long freq = 0;
    double result = 0;
    QueryPerformanceFrequency(ref freq);
    QueryPerformanceCounter(ref count);

    //耗时巨大的代码

    QueryPerformanceCounter(ref count1);
    count = count1 - count;
    result = (double)(count) / (double)freq;
    Console.WriteLine("QueryPerformanceCounter耗时: {0} 秒", result);
}

 1         [System.Runtime.InteropServices.DllImport("Kernel32.dll")]
 2         static extern bool QueryPerformanceCounter(ref long count);
 3         [System.Runtime.InteropServices.DllImport("Kernel32.dll")]
 4         static extern bool QueryPerformanceFrequency(ref long count);  
 5         public static void SubTest()
 6         {
 7             long count = 0;
 8             long count1 = 0;
 9             long freq = 0;
10             double result = 0;
11             QueryPerformanceFrequency(ref freq);
12             QueryPerformanceCounter(ref count);
13             //Shuffle(a) is the function you want to test.
14             int[] a = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
15             Shuffle(a);
16             QueryPerformanceCounter(ref count1);
17             count = count1 - count;
18             result = (double)(count) / (double)freq;
19             //Note:The result is counted by second.
20             Console.WriteLine("DateTime costed for Shuffle function is: {0} s", result);
21         }