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            "Delphi X-Files" <www.DelphiXFiles.narod.ru>"
"Îïðåäåëåíèå ðàçìåðà äèñêîâîãî ïðîñòðàíñòâà äèñêîâ, åìêîñòü áîëåå 2 Ãá"
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function GetDiskFreeSpaceEx(lpDirectoryName: PAnsiChar; 
                            var lpFreeBytesAvailableToCaller : Integer; 
                            var lpTotalNumberOfBytes: Integer; 
                            var lpTotalNumberOfFreeBytes: Integer) : bool; 
                           stdcall; 
                           external kernel32 
                           name 'GetDiskFreeSpaceExA'; 
 
procedure GetDiskSizeAvail(TheDrive : PChar; 
                           var TotalBytes : double; 
                           var TotalFree : double); 
var 
  AvailToCall : integer; 
  TheSize : integer; 
  FreeAvail : integer; 
begin 
  GetDiskFreeSpaceEx(TheDrive, AvailToCall, TheSize, FreeAvail); 
  {$IFOPT Q+} 
    {$DEFINE TURNOVERFLOWON} 
    {$Q-} 
  {$ENDIF} 
  if TheSize >= 0 then 
      TotalBytes := TheSize else 
         if TheSize = -1 then begin 
            TotalBytes := $7FFFFFFF; 
            TotalBytes := TotalBytes * 2; 
            TotalBytes := TotalBytes + 1; 
           end else 
           begin 
             TotalBytes := $7FFFFFFF; 
             TotalBytes := TotalBytes + abs($7FFFFFFF - TheSize); 
           end; 
           if AvailToCall >= 0 then 
             TotalFree := AvailToCall else 
           if AvailToCall = -1 then begin 
             TotalFree := $7FFFFFFF; 
             TotalFree := TotalFree * 2; 
             TotalFree := TotalFree + 1; 
           end else 
         begin 
           TotalFree := $7FFFFFFF; 
           TotalFree := TotalFree + abs($7FFFFFFF - AvailToCall); 
         end; 
       end; 

procedure TForm1.Button1Click(Sender: TObject); 
var 
  TotalBytes : double; 
  TotalFree : double; 
begin 
  GetDiskSizeAvail('C:\', TotalBytes, TotalFree); 
  ShowMessage(FloatToStr(TotalBytes)); 
  ShowMessage(FloatToStr(TotalFree)); 
end;