C#计算一段程序运行时间的三种方法

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);
}

static void SubTest()
{
Stopwatch sw = new Stopwatch();
sw.Start();

//耗时巨大的代码

sw.Stop();
TimeSpan ts2 = sw.Elapsed;
Console.WriteLine("Stopwatch总共花费{0}ms.", ts2.TotalMilliseconds);
}

[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);
}