FDOM 和DOM-------------FDOM返回参数中日期所在月份的第一天的日期。而LDOM返回该月份的最后一天的日期（所给日期的下一个月的第一天日期减去一）。  function FDOM(Date: TDateTime): TDateTime;  var    Year, Month, Day: Word;  begin    DecodeDate(Date, Year, Month, Day);    Result := EncodeDate(Year, Month, 1);  end;  function LDOM(Date: TDateTime): TDateTime;  var    Year, Month, Day: Word;  begin    DecodeDate(Date, Year, Month, Day);    if Month < 12 then inc(Month)    else begin Month := 1; inc(Year) end;    Result := EncodeDate(Year, Month, 1) - 1;  end;调用示范-----------  procedure TForm1.Button1Click(Sender: TObject);  begin    ShowMessage(DateToStr(FDOM(Now)));    ShowMessage(DateToStr(LDOM(Now)));  end;