procedure TFormCalculate.FormCreate(Sender: TObject); begin FCalculator := TCalculator.Create; //在窗口创建时创建计算者生命 end;
procedure TFormCalculate.BtnCalculateClick(Sender: TObject); var A,B,C : Real; begin A := StrToFloat(EdA.Text); //计算者用户发出”计算“指令时 B := StrToFloat(EdB.Text); C := FCalculator.Plus(A,B); //调用计算着的"求加"方法 EDC.Text := FloattoStr(C); end;
procedure TFormCalculate.FormDestroy(Sender: TObject); begin FCalculator.Free; //在窗口关闭时结束计算者生命 end;
{TCalculator} //计算者类 Function TCalculator.Plus(A,B : Extended) : Extended; //“求加”法实现 begin Result := A + B; end;