delphi - D2007 中的指针算术如何使其工作？

Question

在 Delphi 2007 中编译 Embarcadero VirtualShellTools 时:http://embtvstools.svn.sourceforge.net/

function TShellIDList.InternalChildPIDL(Index: integer): PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
begin
  if Assigned(FCIDA) and (Index > -1) and (Index < PIDLCount) then
    Result := PItemIDList( PByte(FCIDA) 
                         + PDWORD(PByte(@FCIDA^.aoffset)
                                  +sizeof(FCIDA^.aoffset[0])*(1+Index))^)
  else
    Result := nil
end;

我收到此错误:

[Pascal Error] IDEVirtualDataObject.pas(1023): E2015 Operator not applicable to this operand type

这段代码有什么问题，我需要进行什么样的类型转换才能使其真正工作？

我在以下(不太复杂的)例程中遇到相同的错误:

function TShellIDList.InternalParentPIDL: PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
begin
  if Assigned(FCIDA) then
      Result :=  PItemIDList( PByte(FCIDA) + FCIDA^.aoffset[0])
  else
    Result := nil
end;

Answer 1

Pointermath 是在 Delphi 2009 中引入的。在 Delphi 2007 中您可以做的最好的事情就是使用 Inc 过程来代替:

function TShellIDList.InternalChildPIDL(Index: integer): PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
var
  Tmp, Tmp2: PByte;

begin
  if Assigned(FCIDA) and (Index > -1) and (Index < PIDLCount) then begin
    Tmp2:= PByte(@FCIDA^.aoffset);
    Inc(Tmp2, sizeof(FCIDA^.aoffset[0])*(1+Index));
    Tmp:= PByte(FCIDA);
    Inc(Tmp, PDWORD(Tmp2)^);
    Result := PItemIDList(Tmp);
  end
  else
    Result := nil
end;