C#.NET 日期操作類

 

代碼

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace Pub.Class
{
/// <summary>
/// 日期操作類
/// </summary>
    public class Date
    {

#region ExactTimeSpan
/// <summary>
/// 精確的時間差
/// </summary>
/// <example>
/// <code>
/// context.items["beginrequesttickcount"]=a.gettickcount();
/// 程式碼片段
/// new TimeSpan(A.GetTickCount()-(long)Context.Items["BeginRequestTickCount"]).TotalMilliseconds
/// </code>
/// </example>
        public class ExactTimeSpan { 
            [DllImport("kernel32.dll")]
static extern bool QueryPerformanceCounter([In, Out] ref long lpPerformanceCount);
            [DllImport("kernel32.dll")]
static extern bool QueryPerformanceFrequency([In, Out] ref long lpFrequency);
static long _f = 0;
/// <summary>
/// 來紀錄程式開始時的TickCount
/// </summary>
/// <returns>TickCount</returns>
            static public long GetTickCount() {
long f = _f;
if (f == 0)
if (QueryPerformanceFrequency(ref f)) _f = f; else _f = -1;

if (f == -1)  return Environment.TickCount * 10000;
long c = 0;
                QueryPerformanceCounter(ref c);
return (long)(((double)c) * 1000 * 10000 / ((double)f));
            }

static long _tc = 0;//GetTickCount()為0時的DateTime.Ticks值

/// <summary>
/// 這個返回的不是真正的精確時間，但時間與時間的差是精確的。
/// GetExactNow與DateTime.Now的偏差比DateTime.Now的精度還要小
/// </summary>
/// <returns>時間與時間差</returns>
            static public DateTime GetExactNow() {
if (_tc == 0) {
long tc = GetTickCount();
                    DateTime dt = DateTime.Now;
                    _tc = dt.Ticks - tc;
return dt;
                }
return new DateTime(_tc + GetTickCount());
            }
        }
#endregion

    }
}