C#中Stopwatch类实现精确代码执行时间测量的两种方案

using System;
using System.Diagnostics;
class Program
{
    static void Main()
    {
        var stopwatch = Stopwatch.StartNew();
        // 模拟耗时操作
        for (int i = 0; i < 1000000; i++) { }
        stopwatch.Stop();
        Console.WriteLine($"基础用法 - 执行时间: {stopwatch.ElapsedMilliseconds}ms");
        Console.WriteLine($"精确时间: {stopwatch.Elapsed.TotalSeconds:F6}秒");
    }
}

using System;
using System.Collections.Generic;
using System.Diagnostics;
class CodeTimer
{
    private Stopwatch _stopwatch = new Stopwatch();
    private Queue<long> _timeRecords = new Queue<long>();
    private long _totalTime;
    private const int MaxRecords = 10;
    public double AverageTimeMs => _timeRecords.Count > 0 ? _totalTime / (double)_timeRecords.Count : 0;
    public void Start()
    {
        _stopwatch.Restart();
    }
    public void StopAndPrint(string operationName)
    {
        _stopwatch.Stop();
        long elapsedMs = _stopwatch.ElapsedMilliseconds;
        _timeRecords.Enqueue(elapsedMs);
        _totalTime += elapsedMs;
        if (_timeRecords.Count > MaxRecords)
        {
            _totalTime -= _timeRecords.Dequeue();
        }
        Console.WriteLine($"{operationName}: {elapsedMs}ms");
    }
}

// 使用 Task.Run 来快速启动一个后台任务
Task.Run(() => 
{
    Console.WriteLine($"任务运行在线程 {Thread.CurrentThread.ManagedThreadId}");
    Thread.Sleep(1000); // 模拟耗时操作
    Console.WriteLine("任务完成！");
});

// 使用 Task.Factory.StartNew 来处理长时间运行的任务
Task.Factory.StartNew(() => 
{
    Console.WriteLine($"任务运行在线程 {Thread.CurrentThread.ManagedThreadId}");
    // 模拟CPU密集型计算
    for (int i = 0; i < 1000000; i++) {}
}, TaskCreationOptions.LongRunning); // 提示这是一个长任务

var task = new Task(() => 
{
    Console.WriteLine($"任务运行在线程 {Thread.CurrentThread.ManagedThreadId}");
    File.WriteAllText("test.txt", "Hello Task!");
});
task.Start(); // 需要手动启动任务

var tasks = new List<Task>();
for (int i = 0; i < 5; i++)
{
    int taskId = i; // 避免闭包陷阱
    tasks.Add(Task.Run(() => 
    {
        Console.WriteLine($"任务{taskId}开始执行");
        Thread.Sleep(1000 * (taskId + 1));
        Console.WriteLine($"任务{taskId}完成");
    }));
}
await Task.WhenAll(tasks); // 等待所有任务完成
Console.WriteLine("所有任务都完成了！");

Task<int> fibonacciTask = Task.Run(() => 
{
    int Fib(int n) => n <= 1 ? n : Fib(n - 1) + Fib(n - 2);
    return Fib(35); // 计算斐波那契数列第35项
});
Console.WriteLine("正在拼命计算中...");
int result = await fibonacciTask;
Console.WriteLine($"计算结果: {result}");

Task.Run(() => 
{
    Console.WriteLine("第一阶段：数据准备");
    return"原始数据";
})
.ContinueWith(previousTask => 
{
    Console.WriteLine($"第二阶段：处理 {previousTask.Result}");
    return$"处理后的-{previousTask.Result}";
})
.ContinueWith(previousTask => 
{
    Console.WriteLine($"第三阶段：存储 {previousTask.Result}");
    File.WriteAllText("data.txt", previousTask.Result);
});