设计模式——简单工厂模式（C++实现）

 #include <iostream>
 #include <string>

 using namespace std;

 class COperator
 {
 public:
         virtual double GetResult()=;

 public:
         COperator()
         {
         }
         COperator(double number_a, double number_b): m_numberA(number_a), m_numberB(number_b)
         {
         }
         double m_numberA;
         double m_numberB;
 };

 class CSub: public COperator
 {
 public:
         CSub()
         {
         }
         CSub(double number_a, double number_b): COperator(number_a, number_b)
         {
         }
         virtual double GetResult();
 };

 double CSub::GetResult()
 {
         return this->m_numberA - this->m_numberB;
 }

 class CAdd: public COperator
 {
 public:
         CAdd()
         {
         }
         CAdd(double number_a, double number_b): COperator(number_a, number_b)
         {
         }
         virtual double GetResult();
 };

 double CAdd::GetResult()
 {
         return m_numberA + m_numberB;
 }

 class CFactory
 {
 public:
         static COperator* CreateOperation(char sOpeType);
 };

 COperator* CFactory::CreateOperation(char sOpeType)
 {
         switch(sOpeType)
         {
                 case '-':
                         return new CSub();
                         break;
                 case '+':
                         return new CAdd();
                         break;
                 default:
                         break;
         }
 }

 int main(void)
 {
         COperator* oper = CFactory::CreateOperation('-');
         oper->m_numberA = ;
         oper->m_numberB = ;
         cout<< "oper->m_numberA: "<< oper->m_numberA<< endl;
         cout<< "oper->m_numberB: "<< oper->m_numberB<< endl;
         cout<< oper->GetResult()<< endl;

         return ;
 }
 ////////////////////////
 [root]$ ./2_simple_factory
 oper->m_numberA:
 oper->m_numberB:
 -