【愚公系列】2023年02月 .NET/C#知识点-程序运行计时的总结

using System.Diagnostics;

Stopwatch sw = new Stopwatch();
sw.Start();
Thread.Sleep(999);
sw.Stop();
Console.WriteLine($"程序耗时：{sw.ElapsedMilliseconds}ms.");

Console.ReadKey();

var start = DateTime.Now;
Thread.Sleep(999);
var stop = DateTime.Now;
Console.WriteLine($"程序耗时：{(stop - start).TotalMilliseconds}ms.");
Console.ReadKey();

using System.Diagnostics;

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);
    }
}