Delphi一句话帮助

1.如果想你的程序能够正确处理异常情况的话，请引用SysUtils.pas单元，否则即使程序使用了try。。。except。。。也不能正确捕获异常。

2.定义常量字符串的一种方式

resourcestring

    aa='aaaa';

raise Exception.CreateRes(@aa);

3. 字符串常量数组的初始化

const  constarray:array [0..2] of string=(‘first’,’second’,’third’);

4. 结构体初始化

type  Tstructinit=record

   A1:integer;

   A2:array [0..2] of integer;

End;

Const m_structinit:Tstructinit=(A1:0;A2:(0,1,2));

5.       多维数组的长度

var  array2:array of array of integer;

setlength(array2,2,2);

6.使用Create和New开辟的空间都存在于堆中，不能自动释放，建议使用FreeAndNil释放, 参数以及局部变量存在于栈中，自动释放。

7.SizeOf不适合于对象，返回的总是4；对于固定类型可以正确返回.

8. Create(nil)需要手工释放，Creat(self)会随着拥有者的释放而释放.

9.动态改变已定义常量的值

procedure ChangeConst(const Const;var Value;Size:Integer);

begin

  Move((@Value)^,(@Constant)^,Size);

End;

10.进行删除操作的时候循环使用DownTo,会避免错误.

11. 汉字的Ascii码>128，可以用它来判别是否为汉字

12. dll编写中，需要使用Sharemem单元来引用BORLANDMM.DLL内存管理.

13.   PostMessage只将消息放到消息队列中，需要排队等待处理。

SendMessage绕过消息队列直接发送到窗口过程,等到消息处理返回值才返回.

14.鼠标移入移出消息：CM_MOUSEENTER,CM_MOUSELEAVE

15. 关机消息WM_QUERYENDSESSION

16.可以利用ThintWindow和类的方法ActivateHint来创建浮动窗体.

17.调出文件属性对话框

uses ShellAPI;

function ShowFileProperties(FileName: String; Wnd: HWND):Boolean;

var

  sfi: TSHELLEXECUTEINFO;

begin

  with sfi do

  begin

    cbSize := SizeOf(sfi);

    lpFile := PAnsiChar(FileName);

    Wnd := Wnd;

    fMask := SEE_MASK_NOCLOSEPROCESS or SEE_MASK_INVOKEIDLIST or SEE_MASK_FLAG_NO_UI;

    lpVerb := PAnsiChar('properties');

    lpIDList := nil;

    lpDirectory := nil;

    nShow := 0;

    hInstApp := 0;

    lpParameters := nil;

    dwHotKey := 0;

    hIcon := 0;

    hkeyClass := 0;

    hProcess := 0;

    lpClass := nil;

  end;

  Result := ShellExecuteEX(@sfi);

end;

 

procedure TForm1.Button1Click(Sender: TObject);

begin

   ShowFileProperties('c:/AA.txt', Handle);

end;

18.   更改系统时间

uses Windows,Dialogs,Forms;

var MyTime:TsystemTime;

begin

  FillChar(MyTime,sizeof(MyTime),#0);

  MyTime.wYear:=2003;

  MyTime.wMonth:=06;

  MyTime.wDay:=01;

  If not SetSystem(MyTime) then

Showmessage(‘Failure’);

   End;

19.复制文件夹Xcopy

.   procedure Xcopy(SourceDir,DestinationDir:String);

    var

      Search : TSearchRec;

     Rec    : word;

Begin

     SourceDir := SourceDir + '/';

      Rec := FindFirst(SourceDir + '*.*', faAnyFile, Search);

     While Rec = 0 Do

      Begin

        If Search.Name[1] <> '.' Then

        Begin

          If (Search.Attr And faDirectory) = faDirectory Then

          Begin

            Windows.CreateDirectory(PChar(DestinationDir + '/' + Search.Name), nil);

            FileSetAttr(DestinationDir + '/' + Search.Name, FileGetAttr(SourceDir + '/' + Search.Name));

            X_Copy(SourceDir + '/' + Search.Name, DestinationDir + '/' + Search.Name);

          end

          Else

          Begin

            CopyFile(PChar(SourceDir + '/' + Search.Name),PChar(DestinationDir + '/' + Search.Name), True);

            FileSetAttr(DestinationDir + '/' + Search.Name, FileGetAttr(SourceDir + '/' + Search.Name));

            Application.ProcessMessages;

          end;

        end;

        Rec := FindNext(Search);

      end;

      FindClose(Search);

end;

20.绘制透明位图

   procedure DrawTrans(DestCanvas: TCanvas; X,Y: smallint; SrcBitmap: TBitmap; AColor, BackColor: TColor);

var  ANDBitmap, ORBitmap: TBitmap;

         CM: TCopyMode;

         Src: TRect;

begin

      ANDBitmap:= NIL;

      ORBitmap:=  NIL;

      try

        ANDBitmap:= TBitmap.Create;

        ORBitmap:= TBitmap.Create;

        Src  := Bounds(0,0, SrcBitmap.Width, SrcBitmap.Height);

        with ORBitmap do begin

          Width:= SrcBitmap.Width;

          Height:= SrcBitmap.Height;

          Canvas.Brush.Color := clBlack;

          Canvas.CopyMode := cmSrcCopy;

          Canvas.BrushCopy(Src, SrcBitmap, Src, AColor);

        end;

        with ANDBitmap do begin

          Width:= SrcBitmap.Width;

          Height:= SrcBitmap.Height;

         Canvas.Brush.Color := BackColor;

         Canvas.CopyMode := cmSrcInvert;

         Canvas.BrushCopy(Src, SrcBitmap, Src, AColor);

       end;

       with DestCanvas do begin

         CM := CopyMode;

         CopyMode := cmSrcAnd;

         Draw(X,Y, ANDBitmap);

         CopyMode := cmSrcPaint;

         Draw(X,Y, ORBitmap);

         CopyMode := CM;

       end;

     finally

       ANDBitmap.Free;

       ORBitmap.Free;

     end;

end;

 

procedure TForm1.Button4Click(Sender: TObject);

begin

    DrawTrans(Image1.Canvas, 0,0, Image2.Picture.Bitmap, clBlack, clSilver);

end;

21. 获取CPU速度

  function GetCpuSpeed: Extended;

var

    t, mhi, mlo, nhi, nlo: dword;

    shr32 : comp;

begin

    shr32 := 65536;

    shr32 := shr32 * 65536;

    t := GetTickCount;

    while t = GetTickCount do ;

      asm

      DB 0FH,031H // rdtsc

      mov mhi,edx

      mov mlo,eax

    end;

    while GetTickCount < (t + 1000) do ;

      asm

      DB 0FH,031H // rdtsc

      mov nhi,edx

      mov nlo,eax

    end;

    Result := ((nhi * shr32 + nlo) - (mhi * shr32 + mlo)) / 1E6;

end;

 

procedure TForm1.Button4Click(Sender: TObject);

begin

    label1.Caption := FloatToStr(GetCpuSpeed) + 'mhz';

end;