C++虚函数的使用示例

本文通过一段简短的示例程序，展示在c++中virtual函数的使用方式

示例程序：

#include <iostream>
#include <memory>

class A {
public:
    void Setup(){
        std::cout << "setup in A" << std::endl;

        layerSetup();
        reshape();
    }

    virtual void layerSetup() { std::cout <<"virtual layerSetup in A" <<std::endl; };
    virtual void reshape(){ std::cout <<"virtual reshape in A" <<std::endl; };
};

class B:public A{
    void layerSetup(){
        std::cout << "layerSetup in B" << std::endl;
    }

    void reshape(){
        std::cout << "reshape in B" << std::endl;
    }
};

int main(){
    std::shared_ptr<B> ptr(new B);
    ptr->Setup();

    std::shared_ptr<A> pc(new A);
    pc->Setup();
    
    B insb;
    insb.Setup();

    A insa;
    insa.Setup();
   
    return 0;
}

输出：

setup in A
layerSetup in B
reshape in B

setup in A
virtual layerSetup in A
virtual reshape in A

setup in A
layerSetup in B
reshape in B

setup in A
virtual layerSetup in A
virtual reshape in A