C++中的虚函数

终于放假了，可以想干嘛干嘛了，今天早上想到以前看过几篇大神的博客，里面提到说用父类的指针去访问子类的函数。。今天早上没什么事，就来验证一下。

[cpp]
#include<iostream>
using namespace std;
class Base
{
    public:
    Base()
    {
        cout<<"initial Base Class"<<endl;
    }
    void name()
    {
        cout<<"Base Class name"<<endl;
    }

};
class Derived1:public Base
{
    public:
        Derived1()
        {
            cout<<"initial Derived Class"<<endl;
        }
        void name()
        {
            cout<<"Derived1 Class name"<<endl;
        }
};
int main()
{
    Derived1 Derived1Class;
    Derived1Class.name();
    //这个当然是可以正常运行的

    Base* BaseClassPointer;
    BaseClassPointer=(Base*)&Derived1Class;
    BaseClassPointer->name();
    //这样相当于把子类转换为父类类型，然后去调用父类的name函数
    return 0;
}

#include<iostream>
using namespace std;
class Base
{
    public:
    Base()
    {
        cout<<"initial Base Class"<<endl;
    }
    void name()
    {
        cout<<"Base Class name"<<endl;
    }

};
class Derived1:public Base
{
    public:
        Derived1()
        {
            cout<<"initial Derived Class"<<endl;
        }
        void name()
        {
            cout<<"Derived1 Class name"<<endl;
        }
};
int main()
{
    Derived1 Derived1Class;
    Derived1Class.name();
    //这个当然是可以正常运行的

    Base* BaseClassPointer;
    BaseClassPointer=(Base*)&Derived1Class;
    BaseClassPointer->name();
    //这样相当于把子类转换为父类类型，然后去调用父类的name函数
    return 0;
}

运行结果

[cpp]
initial Base Class
initial Derived Class   //初始化Deerived类
Derived1 Class name     //调用Derived类的name()
Base Class name   //发生强制转换，最终调用的是基类的name()

initial Base Class
initial Derived Class   //初始化Deerived类
Derived1 Class name     //调用Derived类的name()
Base Class name   //发生强制转换，最终调用的是基类的name()
在不使用虚函数的情况下，用基类的指针去访问子类的函数。这样做就相当于把Derived1类型的对象强制转换为Base类型的，所以函数最终调用的是基类中的name()函数。

使用虚函数就可以实现用基类的指针去访问子类的函数，代码如下:

[cpp]
#include<iostream>
using namespace std;
class Base
{
    public:
        Base()
        {
            cout<<"initial Base Class"<<endl;
        }
        virtual void name()    //用虚函数来实现
        {
            cout<<"Base Class name"<<endl;
        }
        virtual ~Base()
        {
        }
};
class Derived1:public Base
{
    public:
        Derived1()
        {
            cout<<"initial Derived Class"<<endl;
        }
        void name()
        {
            cout<<"Derived1 Class name"<<endl;
        }
        ~Derived1()
        {
        }
};
int main()
{
    Derived1 Derived1Class;
    Derived1Class.name();
    //这个当然是可以正常运行的

    Base* BaseClassPointer = (Base*)&Derived1Class;
    BaseClassPointer->name();
    return 0;
}

#include<iostream>
using namespace std;
class Base
{
    public:
        Base()
        {
            cout<<"initial Base Class"<<endl;
        }
        virtual void name()    //用虚函数来实现
        {
            cout<<"Base Class name"<<endl;
        }
        virtual ~Base()
        {
        }
};
class Derived1:public Base
{
    public:

补充：软件开发 , C++ ,