Question

在Delphi中，我了解如何构建失效计时器。但我不确定如何为C ++ Builder编写代码。我找不到任何例子。

在Delphi中，我在下面编写了这段代码，来自某个地方的源代码： -

boost::thread

请在C ++中如何做同样的事情。感谢

Answer 1

试试这个：

....
class TFrame2 : public TFrame
{
__published:
    TStatusBar *StatusBar1;
    TTimer *Timer1;
    ...
    void __fastcall Timer1Timer(TObject *Sender);
    ...
private:
    TDateTime StartTime;
    ...
public:
    __fastcall TFrame2(TComponent *TheOwner);
};

__fastcall TFrame2::TFrame2(TComponent *TheOwner)
    : TFrame(TheOwner)
{
    StartTime = Now();
    Timer1->Enabled = true;
}

void __fastcall TFrame2::Timer1Timer(TObject *Sender) //This event occurs every second.
{
    Timer1->Enabled = false;

    TDateTime Diff = Now() - StartTime;
    Word Hour, Min, Sec, MSec;
    DecodeTime(Diff, Hour, Min, Sec, MSec);
    StatusBar1->Panels->Items[1]->Text = String(Min)+" Minutes, "+String(Sec)+" Seconds.";

    Timer1->Enabled = true;
}

...

或者，您可以将Timer1Timer()简化为：

void __fastcall TFrame2::Timer1Timer(TObject *Sender) //This event occurs every second.
{
    // this is not overhead-intense code, so
    // stopping and re-starting the timer
    // is wasting unnecessary processing time...

    //Timer1->Enabled = true;

    TDateTime Diff = Now() - StartTime;
    StatusBar1->Panels->Items[1]->Text = Diff.FormatString("n' Minutes, 's' Seconds.'");

    //Timer1->Enabled = true;
}

就个人而言，我根本不会使用系统时钟，以防用户更改时钟，或者在计时器运行时自动滚动DST。我会手动使用CPU滴答：

....
class TFrame2 : public TFrame
{
__published:
    TStatusBar *StatusBar1;
    TTimer *Timer1;
    ...
    void __fastcall Timer1Timer(TObject *Sender);
    ...
private:
    DWORD StartTime;
    ...
public:
    __fastcall TFrame2(TComponent *TheOwner);
};

__fastcall TFrame2::TFrame2(TComponent *TheOwner)
    : TFrame(TheOwner)
{
    StartTime = GetTickCount();
    Timer1->Enabled = true;
}

void __fastcall TFrame2::Timer1Timer(TObject *Sender) //This event occurs every second.
{
    //Timer1->Enabled = false;

    DWORD Diff = GetTickCount() - StartTime;
    DWORD Mins = Diff / 60000; Diff %= 60000;
    DWORD Secs = Diff / 1000;

    StatusBar1->Panels->Items[1]->Text = String(Mins)+" Minutes, "+String(Secs)+" Seconds.";

    //Timer1->Enabled = true;
}

...

或通过TStopWatch：

#include <System.Diagnostics.hpp>

....
class TFrame2 : public TFrame
{
__published:
    TStatusBar *StatusBar1;
    TTimer *Timer1;
    ...
    void __fastcall Timer1Timer(TObject *Sender);
    ...
private:
    TStopwatch SW;
    ...
public:
    __fastcall TFrame2(TComponent *TheOwner);
};

__fastcall TFrame2::TFrame2(TComponent *TheOwner)
    : TFrame(TheOwner)
{
    SW = TStopwatch::StartNew();
    Timer1->Enabled = true;
}

void __fastcall TFrame2::Timer1Timer(TObject *Sender) //This event occurs every second.
{
    //Timer1->Enabled = false;
    SW.Stop();

    TTimeSpan TS = SW.Elapsed;
    StatusBar1->Panels->Items[1]->Text = String(TS.Minutes)+" Minutes, "+String(TS.Seconds)+" Seconds.";

    SW.Start();
    //Timer1->Enabled = true;
}

定义并构建已失效的计时器

1 个答案: