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实现毫秒级和纳秒级计数的几个API--timeGetTime、GetTickCount、QueryPerformanceCoun

http://club.excelhome.NET/thread-907289-1-1.html

【你不是一个人在学习VB6】在此基础上做了少量改动，以更好地演示几个API的计时效果。

窗体上放一个命令按钮。窗体代码如下：

Option ExplicitPrivate Declare Function timeGetTime Lib "winmm.dll" () As LongPrivate Declare Function GetTickCount Lib "kernel32" () As LongPrivate Declare Function QueryPerformanceCounter Lib "kernel32 " (lpPerformanceCount As Any) As LongPrivate Declare Function QueryPerformanceFrequency Lib "kernel32 " (lpFrequency As Any) As LongPrivate Declare Sub Sleep Lib "KERNEL32.dll" (ByVal dwMilliseconds As Long)Private Sub Command1_Click()  timeCountEnd SubSub timeCount()    Dim curFrequency As Currency    Dim curStart As Currency    Dim curEnd As Currency    Dim delayms%    '    delayms = 66'    delayms = 1    Randomize    delayms = Int((1000 - 1 + 1) * Rnd + 1)    Me.Caption = "要求 sleep " & delayms & "毫秒，实际结果是："    QueryPerformanceFrequency curFrequency    QueryPerformanceCounter curStart            '精度100ns    Sleep delayms    QueryPerformanceCounter curEnd    MsgBox "QueryPerformanceCounter计时： " & (curEnd - curStart) / curFrequency * 1000 & "毫秒"        curStart = Timer               '精度55ms    Sleep delayms    MsgBox "Timer计时： " & (Timer - curStart) * 1000 & "毫秒"        curStart = GetTickCount        '精度55ms    Sleep delayms    MsgBox "GetTickCount计时： " & (GetTickCount - curStart) & "毫秒"        curStart = timeGetTime         '精度10ms    Sleep delayms    MsgBox "timeGetTime计时： " & (timeGetTime - curStart) & "毫秒"    Me.Caption = "请继续。。。"End Sub