Multi-State computer program

I. Create a form

Two. Create a class operator there are two operands and one method

Public  abstract  class Operator    {public     abstract int Calc ();     Count public     int Numleft {get; set;}     public int Numright {get; set;}    }

Three. Create an Add Class

public class Add:operator    {public        override int Calc ()        {            return this. Numleft + this. numright;        }    }

Four. Create a sub Class

Public    class Sub:operator    {public        override int Calc ()        {            return this. Numleft-this. numright;        }    }

Five. Create a Mul class

Public    class Mul:operator    {public        override int Calc ()        {            return this. Numleft * this. numright;        }    }

Six. Create a DIV class

Public   class Div:operator    {public           override int Calc ()        {            int result = 0;            if (Numleft = = 0)            {                throw new Exception ("divisor cannot be 0");            }            else            {                    result=this. Numleft/this. numright;            }            return result;        }    }

Seven. Create a factory-like class

Public     class Factory    {    //static   return value type    parameter public    static Operator Cu (String Type)    {        Operator Oper=null;        Switch (Type) {case            "+":            oper=new Add ();                break;                Case "-":            oper=new Sub ();                break;                Case "*":            oper=new Mul ();                break;                Case "/":            oper=new Div ();             break;}        return oper;    }    }

　　

Eight. In the results button of the main form, add

  private void Btok_click (object sender, EventArgs e)        {         int num1=convert.toint32 (   txtlfet.text);         String oper = cb. Text;         int num2 = Convert.ToInt32 (txtright.text);         04. Call the factory's static method, pass in the type, get the return value         Operator part = FACTORY.CU (oper);         Part. Numleft = NUM1;         Part. Numright = num2;         int result = 0;         05. Call the Calc () that corresponds to the parent class variable to complete the calculation, and receive the return value of         try         {             result = part. Calc ();         }         catch (Exception ex)         {             MessageBox.Show (ex. Message);         }         06. Display the Label1 in the label         . Text = result. ToString ();        }

　　

　　

Multi-State computer program