小王正在编写一个简单的计算器程序,要求输入两个整数和运算符号(加、减、乘、除),输出计算结果。小王用面向过程方法编写了下面的代码。请采用面向对象方法通过恰当的设计模式对小王的代码进行重构。
int main()
{
int numa,numb; char oper; double result;
cin>>numa>>numb; cin>>oper;
switch(oper) {
case '+': result=numa+numb; break;
case '-': result=numa-numb; break;
case '*': result=numa*numb; break;
case '/': result=numa/(double)numb; break;
}
cout<<result<<endl;
return 0;
}
#include<string>
#include<iostream>
using namespace std;
//抽象产品角色
class COperation{
public:
int m_nFirst;
int m_nSecond;
virtual double GetResult(){
double dResult = 0;
return dResult;
}
};
//具体产品角色
class AddOperation :public COperation{
public:
virtual double GetResult(){
return m_nFirst + m_nSecond;
}
};
class SubOperation :public COperation{
public:
virtual double GetResult(){
return m_nFirst - m_nSecond;
}
};
class MultiOperation :public COperation{
public:
virtual double GetResult(){
return m_nFirst*m_nSecond;
}
};
class DiviOperation :public COperation{
public:
virtual double GetResult(){
return m_nFirst / m_nSecond;
}
};
//工厂角色
class CalculatorFactory{
public:
static COperation* Create(char COperator);
};
COperation* CalculatorFactory::Create(char Coperator){
COperation *oper;
switch (Coperator){
case '+':
oper = new AddOperation();
break;
case '-':
oper = new SubOperation();
break;
case '*':
oper = new MultiOperation();
break;
case '/':
oper = new DiviOperation();
break;
default:
oper = new AddOperation();
}
return oper;
}
//客户
int main(){
int a, b;
cin >> a >> b;
COperation *op = CalculatorFactory::Create('-');
op->m_nFirst = a;
op->m_nSecond = b;
cout << op->GetResult() << endl;
return 0;
}