delphi offsetof , container_of 通過結構體成員獲得到該結構體地址

C宏 offsetof(type, member) 該結構體成員相對於該結構體的偏移量
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

那Delphi版的表示式怎麼寫呢

NativeUInt(@Record(nil^).member)

C宏 container_of() 通過結構體成員得到該結構體地址

那Delphi版的表示式怎麼寫呢

NativeUInt(@member)-NativeUInt(@Record(nil^).member)

例子如下:

 type
  TTestRecord=record
    a:Integer;
    b:Integer;
    c:string;
    d:string;
  end;

procedure TForm2.btn1Click(Sender: TObject);
var
  p,pb,pd:Pointer;
  t:TTestRecord;
  n:NativeUInt;
begin
  p:=@t;
  pb:[email protected];
  pd:[email protected];
  mmo1.Lines.Add('record addr:='+IntToStr(NativeUInt(p)));
  mmo1.Lines.Add('record.b addr:='+IntToStr(NativeUInt(pb)));
  mmo1.Lines.Add('record.d addr:='+IntToStr(NativeUInt(pd)));
  n:= NativeUInt(@TTestRecord(nil^).b);
  mmo1.Lines.Add('record.b len:='+IntToStr(n));
  n:= NativeUInt(@TTestRecord(nil^).d);
  mmo1.Lines.Add('record.d len:='+IntToStr(n));
  n:=NativeUInt(pb)-NativeUInt(@TTestRecord(nil^).b);
  mmo1.Lines.Add('record addr(Calculated by member b):='+IntToStr(n));
  n:=NativeUInt(pd)-NativeUInt(@TTestRecord(nil^).d);
  mmo1.Lines.Add('record addr(Calculated by member d):='+IntToStr(n));
end;

運行結果如下圖