c++ - 从基类实例调用派生类方法而无需强制转换

Question

还有另一种方法可以从基本指针对象调用派生类方法而不进行转换？

class Base
{
};

class Derived : public Base
{
    public:
    void set() {printf("bbbbbbbbbbbb"); }

};

int main()
{
  Base* pbBase;

  pbBase = new Derived();

  //pbBase->set(); // Compilation error.
  (Derived*)pbBase->set(); // Working.
}

Answer 1

您可以在virtual中覆盖的Base中添加Derived方法。

注意，您也应该将析构函数设为virtual，否则当通过基类指针对对象进行delete时，派生类的析构函数将不会被调用。

#include <iostream>

class Base
{
public:
    virtual ~Base() = default;
    virtual void set() = 0;    // = 0 makes it pure virtual
};

class Derived : public Base
{
public:
    void set() override { std::cout << "bbbbbbbbbbbb\n"; }

};

int main()
{
  Base* pbBase;

  pbBase = new Derived();

  pbBase->set();

  delete pbBase;
}