C# 用于准确地测量运行时间的Stopwatch中.Start 方法和Stopwatch.Stop 方法

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一、Stopwatch 类

提供一组方法和属性，可用于准确地测量运行时间。

public class Stopwatch

使用 Stopwatch 类来确定应用程序的执行时间。

// 使用 Stopwatch 类来确定应用程序的执行时间
using System.Diagnostics;
class Program
{static void Main(string[] args){ArgumentNullException.ThrowIfNull(args);Stopwatch stopWatch = new();stopWatch.Start();Thread.Sleep(10000);stopWatch.Stop();// Get the elapsed time as a TimeSpan value.TimeSpan ts = stopWatch.Elapsed;// Format and display the TimeSpan value.string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",ts.Hours, ts.Minutes, ts.Seconds,ts.Milliseconds / 10);Console.WriteLine("RunTime " + elapsedTime);}
}
//运行结果：
/*
RunTime 00:00:10.01*/

// 使用 Stopwatch 类来计算性能数据。
using System.Diagnostics;namespace StopWatchSample
{class OperationsTimer{public static void Main(string[] args){ArgumentNullException.ThrowIfNull(args);DisplayTimerProperties();Console.WriteLine();Console.WriteLine("Press the Enter key to begin:");Console.ReadLine();Console.WriteLine();TimeOperations();}public static void DisplayTimerProperties(){// Display the timer frequency and resolution.if (Stopwatch.IsHighResolution){Console.WriteLine("Operations timed using the system's high-resolution performance counter.");}else{Console.WriteLine("Operations timed using the DateTime class.");}long frequency = Stopwatch.Frequency;Console.WriteLine("  Timer frequency in ticks per second = {0}",frequency);long nanosecPerTick = (1000L * 1000L * 1000L) / frequency;Console.WriteLine("  Timer is accurate within {0} nanoseconds",nanosecPerTick);}private static void TimeOperations(){long nanosecPerTick = (1000L * 1000L * 1000L) / Stopwatch.Frequency;const long numIterations = 10000;// Define the operation title names.string[] operationNames = {"Operation: Int32.Parse(\"0\")","Operation: Int32.TryParse(\"0\")","Operation: Int32.Parse(\"a\")","Operation: Int32.TryParse(\"a\")"};// Time four different implementations for parsing// an integer from a string.for (int operation = 0; operation <= 3; operation++){// Define variables for operation statistics.long numTicks = 0;long numRollovers = 0;long maxTicks = 0;long minTicks = long.MaxValue;int indexFastest = -1;int indexSlowest = -1;Stopwatch time10kOperations = Stopwatch.StartNew();// Run the current operation 10001 times.// The first execution time will be tossed// out, since it can skew the average time.for (int i = 0; i <= numIterations; i++){long ticksThisTime = 0;int inputNum;Stopwatch timePerParse;switch (operation){case 0:// Parse a valid integer using// a try-catch statement.// Start a new stopwatch timer.timePerParse = Stopwatch.StartNew();try{inputNum = int.Parse("0");}catch (FormatException){inputNum = 0;}// Stop the timer, and save the// elapsed ticks for the operation.timePerParse.Stop();ticksThisTime = timePerParse.ElapsedTicks;break;case 1:// Parse a valid integer using// the TryParse statement.// Start a new stopwatch timer.timePerParse = Stopwatch.StartNew();if (!int.TryParse("0", out inputNum)){inputNum = 0;}// Stop the timer, and save the// elapsed ticks for the operation.timePerParse.Stop();ticksThisTime = timePerParse.ElapsedTicks;break;case 2:// Parse an invalid value using// a try-catch statement.// Start a new stopwatch timer.timePerParse = Stopwatch.StartNew();try{inputNum = int.Parse("a");}catch (FormatException){inputNum = 0;}// Stop the timer, and save the// elapsed ticks for the operation.timePerParse.Stop();ticksThisTime = timePerParse.ElapsedTicks;break;case 3:// Parse an invalid value using// the TryParse statement.// Start a new stopwatch timer.timePerParse = Stopwatch.StartNew();if (!int.TryParse("a", out inputNum)){inputNum = 0;}// Stop the timer, and save the// elapsed ticks for the operation.timePerParse.Stop();ticksThisTime = timePerParse.ElapsedTicks;break;default:break;}// Skip over the time for the first operation,// just in case it caused a one-time// performance hit.if (i == 0){time10kOperations.Reset();time10kOperations.Start();}else{// Update operation statistics// for iterations 1-10000.if (maxTicks < ticksThisTime){indexSlowest = i;maxTicks = ticksThisTime;}if (minTicks > ticksThisTime){indexFastest = i;minTicks = ticksThisTime;}numTicks += ticksThisTime;if (numTicks < ticksThisTime){// Keep track of rollovers.numRollovers++;}}}// Display the statistics for 10000 iterations.time10kOperations.Stop();long milliSec = time10kOperations.ElapsedMilliseconds;Console.WriteLine();Console.WriteLine("{0} Summary:", operationNames[operation]);Console.WriteLine("  Slowest time:  #{0}/{1} = {2} ticks",indexSlowest, numIterations, maxTicks);Console.WriteLine("  Fastest time:  #{0}/{1} = {2} ticks",indexFastest, numIterations, minTicks);Console.WriteLine("  Average time:  {0} ticks = {1} nanoseconds",numTicks / numIterations,(numTicks * nanosecPerTick) / numIterations);Console.WriteLine("  Total time looping through {0} operations: {1} milliseconds",numIterations, milliSec);}}}
}
//运行结果：
/*
Operations timed using the system's high-resolution performance counter.Timer frequency in ticks per second = 10000000Timer is accurate within 100 nanoseconds*/