概述

     计算一段程序的耗时是我们在编程中很常见的用法，那这节内容就通过实例的方式来演示几种常用的统计耗时的方法.

方法一：stopwatch

static void Main(string[] args){Stopwatch sw = new Stopwatch();sw.Start();Thread.Sleep(999);sw.Stop();Console.WriteLine($"程序耗时：{sw.ElapsedMilliseconds}ms.");Console.ReadKey();}

最常用的计算耗时的就是使用Stopwatch，使用的时候需要引用命名空间：System.Diagnostics.

运行结果：

程序耗时：1012ms.

方法二：DateTime.Now

static void Main(string[] args){//Stopwatch sw = new Stopwatch();//sw.Start();//Thread.Sleep(999);//sw.Stop();//Console.WriteLine($"程序耗时：{sw.ElapsedMilliseconds}ms.");var start = DateTime.Now;Thread.Sleep(999);var stop = DateTime.Now;Console.WriteLine($"程序耗时：{(stop - start).TotalMilliseconds}ms.");Console.ReadKey();}

运行结果：

程序耗时：1012.2267ms.

方法二：ValueStopwatch

用法举例如下：

using System;
using System.Diagnostics;
using System.Threading;namespace ConsoleApp27
{class Program{ static void Main(string[] args){//Stopwatch sw = new Stopwatch();//sw.Start();//Thread.Sleep(999);//sw.Stop();//Console.WriteLine($"程序耗时：{sw.ElapsedMilliseconds}ms.");//var start = DateTime.Now;//Thread.Sleep(999);//var stop = DateTime.Now;//Console.WriteLine($"程序耗时：{(stop - start).TotalMilliseconds}ms.");var watch = ValueStopwatch.StartNew();Thread.Sleep(999);Console.WriteLine($"程序耗时：{watch.GetElapsedTime().TotalMilliseconds}ms.");Console.ReadKey();}}internal struct ValueStopwatch{private static readonly double TimestampToTicks = TimeSpan.TicksPerSecond / (double)Stopwatch.Frequency;private readonly long _startTimestamp;public bool IsActive => _startTimestamp != 0;private ValueStopwatch(long startTimestamp){_startTimestamp = startTimestamp;}public static ValueStopwatch StartNew() => new ValueStopwatch(Stopwatch.GetTimestamp());public TimeSpan GetElapsedTime(){// Start timestamp can't be zero in an initialized ValueStopwatch. It would have to be literally the first thing executed when the machine boots to be 0.// So it being 0 is a clear indication of default(ValueStopwatch)if (!IsActive){throw new InvalidOperationException("An uninitialized, or 'default', ValueStopwatch cannot be used to get elapsed time.");}var end = Stopwatch.GetTimestamp();var timestampDelta = end - _startTimestamp;var ticks = (long)(TimestampToTicks * timestampDelta);return new TimeSpan(ticks);}}}

运行结果：

程序耗时：1008.0426ms.