獲取磁盤剩餘空間函數

function GetDiskFree(Drive: char): int64;
  {   func   to   return   the   free   space   of   a   drive   in   bytes.   }
var
{$IFDEF   Delphi3Below}
    lpFreeBytesAvailableToCaller,
        lpTotalNumberOfBytes,
        lpTotalNumberOfFreeBytes: comp;
{$ELSE}
    lpFreeBytesAvailableToCaller,
        lpTotalNumberOfBytes,
        lpTotalNumberOfFreeBytes: TLargeInteger;
{$ENDIF}
begin
    if GetDiskFreeSpaceEx(PChar(Drive + ':/'), lpFreeBytesAvailableToCaller,
        lpTotalNumberOfBytes, @lpTotalNumberOfFreeBytes) then
        Result := lpTotalNumberOfFreeBytes
    else
        Result := -1;
end;