使用简单工厂模式改写“生成+-*/”

本代码用于改写 http://www.cnblogs.com/resake/archive/2008/06/23/1228039.html提到的 生成+-*/表达式。

using  System;
using  System.Collections.Generic;

#region  应用程序入口
public   class  Resake
{
     public   static   void  Main()
    {
        Expresstion ea  =  ExpresstionFactory.CreateExpresstion( ' + ' );
        ea.MakeExpresstion();
        ea.ShowResult();
        
        ea  =  ExpresstionFactory.CreateExpresstion( ' - ' );
        ea.MakeExpresstion();
        ea.ShowResult();
        
        Console.ReadLine();
    }

}
#endregion  

#region  实际类
public   abstract   class  Expresstion  // 基类
{
     protected  Random rnd  =   new  Random();
     protected   int  result,num1,num2,input;
     protected   readonly   int  seed  =   20 ;
     public   abstract   void  MakeExpresstion();
     public   virtual   void  ShowResult()
    {
        Console.WriteLine( " num1: {0}, num2: {1}, result: {2} " ,num1,num2,result);
    }
}

public   class  ExpresstionAdd:Expresstion  // 加法
{
     public   override   void  MakeExpresstion()
    {
        result  =  rnd.Next( 1 ,seed);
        num1  =  rnd.Next( 1 ,result);
        num2  =  result  -  num1;        
    }
    
     public   override   void  ShowResult()
    {
        Console.WriteLine( " {0} + {1} = ? ({2}) " ,num1,num2,result);
    }
    
}

public   class  ExpresstionSub:Expresstion  // 减法
{
     public   override   void  MakeExpresstion()
    {
        result  =  rnd.Next( 1 ,seed);
        num2  =  rnd.Next( 1 ,result);
        num1  =  result + num2;
    }
    
     public   override   void  ShowResult()
    {
        Console.WriteLine( " {0} - {1} = ? ({2}) " ,num1,num2,result);
    }
}
#endregion  

#region   简单工厂
public   static   class  ExpresstionFactory
{
     public   static  Expresstion CreateExpresstion( char  operat)
    {
        Expresstion exp  =   null ;
         switch (operat)
        {
             case   ' + ' :
                exp  =   new  ExpresstionAdd();
                 break ;
             case   ' - ' :
                exp  =   new  ExpresstionSub();
                 break ;
        }
         return  exp;
    }
}
#endregion

转载于:https://www.cnblogs.com/resake/archive/2008/06/23/1228272.html