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//因為要建立2個視窗，所以標題改了一下，測試用..
procedure TForm1.FormCreate(Sender: TObject);
var
  dc:THandle;
begin
  Caption:='';
  dc:=FindWindow(nil,'Test1');
  if(dc>0)then Caption:='Test2' else Caption:='Test1';
end;    //傳遞訊息
procedure TForm1.Button1Click(Sender: TObject);
VAR
  R:Trec;
  P:COPYDATASTRUCT;
  dc:THandle;
begin
  R.A:=#0#1#2#3#4#5#6#7;
  R.B:=1;
  R.C:=2;
  if Caption='Test1' then dc:=FindWindow(nil,'Test2')
                     else dc:=FindWindow(nil,'Test1');
  if dc=0 then Showmessage('找不到視窗') else begin
    P.dwData:=dc;
    P.cbData:=Sizeof(R);
    P.lpData:=@R;
    SendMessage(dc,WM_COPYDATA,Handle,Integer(@P));
  end;
end;    //接收用訊息
procedure TForm1.WMCopy(var Msg:TMessage);
var
  R:Trec;
  P:COPYDATASTRUCT;
  function GetStr(Str:String):String;{這函數將Str轉為Hex}
  var i:Integer;
  begin
    Result:='';
    for i:=1 to Length(Str)do Result:=Result ':' IntToHex(Byte(Str[i]),2);
  end;
begin
  memo1.Lines.Add('Wparam:' inttostr(msg.wParam));
  P:=COPYDATASTRUCT(Pointer(Msg.lParam)^);
  R:=TRec(P.lpData^);
  Memo1.Lines.Add('A:' GetStr(r.A));
  memo1.Lines.Add('B:' inttostr(r.B));
  memo1.Lines.Add('C:' inttostr(r.C));
end;