Var
  F: File of Byte;
  Size: LongInt;
begin
  if OpenDialog1.Execute then
    begin
      AssignFile(F, OpenDialog1.FileName);
      Reset(F);
      Size := FileSize(F);
      ShowMessage(OpenDialog1.FileName + '檔案的大小是﹕' +
        IntToStr(Size) + 'Byte');
      //將Size值除以1024后取整就是KB單位﹐再除以1024后取整就是MB單位了
      CloseFile(F);
    end;
end;

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