简单工厂实现简易计算器(c++实现）

Question

1 我想用简单工厂实现简单的计算器，

在主函数输入左右运算数和运算符，在工厂类中通过运算符选择要调用的具体操作——加减乘除，加减乘除各自单独设计一个类，它们都继承自Operation类

2 代码如下

#include <iostream>
#include <cmath>
using namespace std;

class Operation
{
    public:
    Operation(double operandA,double operandB,char operate)
    {
        this->operandA=operandA;
        this->operandB=operandB;
        this->operate=operate;
    }
    protected:
        double operandA;
        double operandB;
        char operate;

    public:
        void setOperandA(double operandA)
        {
            this->operandA=operandA;
        }
        void setOperandB(double operandB)
        {
            this->operandB=operandB;
        }
        void setOperate(char operate)
        {
            this->operate=operate;
        }
        double getOperandA()
        {
            return this->operandA;
        }
        double getOperandB()
        {
            return this->operandB;
        }
        char getOperate()
        {
            return this->operate;
        }
        virtual double getResult()=0;
};
class AddOperation:public Operation
{
    public:
    AddOperation(double operandA,double operandB,char operate):Operation( operandA, operandB, operate){}
    double getResult()
    {
        return operandA+operandB;
    }
};

class MinusOperation:public Operation
{
    public:
    MinusOperation(double operandA,double operandB,char operate):Operation( operandA, operandB, operate){}
    double getResult()
    {
        return operandA-operandB;
    }
};
class MultipleOperation:public Operation
{
    public:
    MultipleOperation(double operandA,double operandB,char operate):Operation( operandA, operandB, operate){}
    double getResult()
    {
        return operandA*operandB;
    }
};
class DivOperation:public Operation
{
    public:
    DivOperation(double operandA,double operandB,char operate):Operation( operandA, operandB, operate){
    }
    double getResult()
    {
//        cout<<operandB<<endl;
        if(fabs(this->operandB)>1e-2)
        {
            return this->operandA/this->operandB;
        }
        return -1;
};
class OperationFactory{


    public :
        Operation *operation=NULL;
    public:
        Operation* createOperation(double operandA,double operandB,char opt)
        {
            switch(opt)
            {
                case '+':
                    {
                        AddOperation add(operandA,operandB,opt);
                        operation=&add;
                    }
                    break;
                case '-':
                    {
                        MinusOperation minus(operandA,operandB,opt);
                        operation=&minus;
                    }
                    break;
                case '*':
                    {
                        MultipleOperation multiple(operandA,operandB,opt);
                        operation=&multiple;
                    }
                    break;
                case '/':
                    {
                        DivOperation div(operandA,operandB,opt);
                        operation=&div;
                    }
                    break;
                default:
                    break;

            }
            return operation;
        }

};
int main()
{
    double oprA,oprB;
    double result;
    char opt;
    cin>>oprA>>oprB>>opt;
//    AddOperation add(oprA,oprB,opt);
//    Operation *op=&add;

    OperationFactory factory;
    Operation *option=factory.createOperation(oprA,oprB,opt);
    result=option->getResult();
    cout<<result;
    return 0;
}

3 问题

在具体操作——加减乘除的实现类中，如DivOperation中，若在该函数体内
判断除数operandB与0的关系语句前，加入
cout<<operandB<<endl;
这样一句话，operandB的值就会错误，导致计算结果也发生错误
比如输入10 10/时

不加这句话结果就对了，请问代码哪里出了问题？

Answer 1

#include<bits/stdc++.h>
#include<windows.h>
using namespace std;
int main()
{
    long long n,a,b,r=1,x,y;
    cout<<"1·求两数和   2·求两数差         3.求两数积          4.求两数商 "<<endl;
    cout<<"5·求a的b次方 6·求两数最大公约数 7·求两数最小公倍数 8·退出运算"<<endl;
    cout<<"温馨提示：第1·3·5·7题和第4题分别存在数据范围问题和精度问题，请谅解！"<<endl;
    cout<<"_________________________________________"<<endl;
    while (1)
    {
        cin>>n;
        if (n==1||n==2||n==3||n==4||n==5||n==6||n==7)
        {
            cout<<"请输入要进行运算的两个数："<<endl;
            cin>>a>>b;
            cout<<"正在运算中......"<<endl;
            Sleep(1000);
        }
        switch (n)
        {
            case 1:
                cout<<a+b;
                break;
            case 2:
                cout<<a-b;
                break;
            case 3:
                cout<<a*b;
                break;
            case 4:
                cout<<double(a)/b;
                break;
            case 5:
                while (b!=0)
                {
                    if (b&1==1)
                    {
                        r*=a;
                    }
                    a*=a;
                    b>>=1;
                }
                cout<<r;
                break;
            case 6:
                x=a;
                y=b;
                r=a%b;
                while (r!=0)
                {
                    a=b;
                    b=r;
                    r=a%b;
                }
                cout<<b;
                break;
            case 7:
                x=a;
                y=b;
                r=a%b;
                while (r!=0)
                {
                    a=b;
                    b=r;
                    r=a%b;
                }
                cout<<x*y/b;
                break;
            case 8:
                goto here;
                break;
            default:
                cout<<"抱歉，目前还未具有此类运算哦！";
                break; 
        }
        cout<<endl<<"_________________________________________"<<endl;
        cout<<"如有需要，请继续使用！"<<endl;
    }
    here:;
    cout<<"_________________________________________"<<endl;
    return 0;
}