类模板进行计算器的模拟出了问题，继承后并没有继承基类的公有成员

Question

#include
using namespace std;
template
class AbstractCalculator
{
public:
T Num1;//操作数1
T Num2;//操作数2
virtual T getresult() = 0;
};
template
class Div :
public AbstractCalculator
{
public:
Div(T a,T b);
T getresult();
};
template
class Minus :
public AbstractCalculator
{
public:
Minus(T a, T b);
T getresult();
};
template
class Multy :
public AbstractCalculator
{
public:
Multy(T a,T b);
T getresult();
};
template
class Plus :public AbstractCalculator
{
public:
Plus(T a, T b);
T getresult();
};
template
Div::Div(T a, T b)
{
Num1 = a;
Num2 = b;
}
template
T Div::getresult()
{
return Num1 / Num2;
}
template
Plus::Plus(T a, T b)
{
Num1 = a;
Num2 = b;
}
template
T Plus::getresult()
{
return Num1 + Num2;
}
template
Minus::Minus(T a, T b)
{
Num1 = a;
Num2 = b;
}
template
T Minus::getresult()
{
return Num1 - Num2;
}
template
Multy::Multy(T a, T b)
{
Num1 = a;
Num2 = b;
}
template
T Multy::getresult()
{
return Num1 * Num2;
}
int main()
{
Plus a(1, 2);
cout << a.Num1 << "+" << a.Num2 << "=" << a.getresult() << endl;
Minus b(1, 2);
cout << b.Num1 << "-" << b.Num2 << "=" << b.getresult() << endl;
Multy c(1, 2);
cout << c.Num1 << "*" << c.Num2 << "=" << c.getresult() << endl;
Div d(1.5, 2.5);
cout << d.Num1 << "/" << d.Num2 << "=" << d.getresult() << endl;
}
这是其中一条报错内容
[Error] 'Num1' was not declared in this scope

Answer 1

要访问的话需要加上父类的域名

AbstractCalculator<T>::Num1

以加法为例，从模板类继承模板类应该写成：

#include <iostream>
using namespace std;

template<typename T>
class AbstractCalculator
{
public:
    T Num1;//操作数1
    T Num2;//操作数2
    virtual T getresult() = 0;
};

template<typename T>
class Plus: public AbstractCalculator<T>
{
public:
    Plus(T a, T b);
    T getresult();
};

template<typename T>
Plus<T>::Plus(T a, T b)
{
    AbstractCalculator<T>::Num1 = a;
    AbstractCalculator<T>::Num2 = b;
}

template<typename T>
T Plus<T>::getresult()
{
    return AbstractCalculator<T>::Num1 + AbstractCalculator<T>::Num2;
}

int main()
{
    Plus<int> a(1, 2);
    cout << a.Num1 << "+" << a.Num2 << "=" << a.getresult() << endl;
    return 0;
}