C++ 简单工厂模式示例：实现加减运算

#include class OperationCls{ public: virtual int GetResult() = 0; private: int NumberA; int NumberB; };

class OperationPlus : public OperationCls { public: int GetResult(){ return NumberA + NumberB;

  }	

}; class OperationSub : public OperationCls{ public: int GetResult(){ return NumberA - NumberB; }

};

class FactoryOperate{ public: OperationCls * CreateOperate(int type){ switch (type) { case 1: return new OperationPlus; break; case 2: return new OperationSub; break; default: break; } } }; int main(){ FactoryOperate *factory = new FactoryOperate(); std::cout<CreateOperate(1)->GetResult(); std::cout<CreateOperate(2)->GetResult();

}

哪里有错内容：在FactoryOperate类的CreateOperate函数中，switch语句的括号应该是(type)，而不是type。修改后的代码如下：

class FactoryOperate{
	public:
		OperationCls * CreateOperate(int type){
			switch (type) {
				case 1:
					return new OperationPlus;
					break;
				case 2:
					return new OperationSub;
					break;
				default:
					break;			
			}	
		}
};