代码记录

设计模式的代码注意要运用到面向对象的思想 考虑到紧耦合和松耦合
把具体的操作类分开 不让其互相影响（注意这点）
下面是UML类图

代码部分

#include <iostream>  
#include <memory> // 引入智能指针的头文件  using namespace std;// 操作基类  
class Operate {
public:Operate() {}virtual ~Operate() {}virtual int GetResult() = 0; // 纯虚函数，强制派生类实现  void  SetNumsA(int A){NumsA = A;}void SetNumsB(int B){NumsB = B;}
protected:int NumsA, NumsB;
};// 加法操作类  
class AddOperate : public Operate {
public:int GetResult() override {return NumsA + NumsB;}
};// 减法操作类  
class SubOperate : public Operate {
public:int GetResult() override {return NumsA - NumsB;}
};// 乘法操作类  
class MulOperate : public Operate {
public:int GetResult() override {return NumsA * NumsB;}
};// 除法操作类  
class DivOperate : public Operate {
public:int GetResult() override {if (NumsB == 0) {throw runtime_error("Division by zero is not allowed.");}return NumsA / NumsB;}
};// 操作工厂类  
class OperateFactory {
public:OperateFactory() {}std::unique_ptr<Operate> CreateOperate(char op) {switch (op) {case '+': return std::make_unique<AddOperate>();case '-': return std::make_unique<SubOperate>();case '*': return std::make_unique<MulOperate>();case '/': return std::make_unique<DivOperate>();default:throw runtime_error("No such operation!");}}
};int main() {try {OperateFactory factory;char op = '/';int numA = 100, numB = 700;std::unique_ptr<Operate> operate = factory.CreateOperate(op);operate->SetNumsA(numA);operate->SetNumsB(0);cout << operate->GetResult() << endl;}catch (const exception& e) {cout << "Error: " << e.what() << endl;}return 0;
}

代码参考书：
大话设计模式