C++ 派生函数与基函数

Question

有没有办法可以在派生类上调用基类的成员函数？

Class Bass{
    public:
        void func();
};

Class Derived: public Base{
    public:
        void func();
};

我有一个期中练习，我怀疑没有，因为基类如何知道派生类，但我不确定。

Answer 1

Is there a way you can invoke a member function of a base class upon a class derived from it?

不确定您的意思，但鉴于您的 Base 和 Derived 类，您可以执行以下操作。只需确保您使用引用或指针，而不是按值传递，因为 slicing problem .

---

从 Derived::func() 中调用 Base::func():

void Derived::func()
{
    Base::func();
}

---

在 Derived 对象上显式调用 Base::func():

Derived d;
d.Base::func();

---

I [...] am wondering if you could do something like Base::func(Derived d)

正如其他人所指出的，您可以使用前向声明来做到这一点:

// Tell the compiler "Derived" is a class name.
class Derived;

class Base
{
    // Can use the class name since it has been declared.
    void func(Derived& derived);
};

// Define the class named "Derived".
class Derived : public Base
{
    // ...
};

// Use the derived class.
void Base::func(Derived& derived)
{
    // For this bit to work, the definition of `Derived` must
    // be visible at this point (like putting the class above
    // or including your "Derived.h" from "Base.cpp").
    derived.some_derived_method();
}

但是，您将无法直接在类定义中定义 Base::func(Derived&)，因为您需要完成定义 Base 并定义首先派生。