c++语法(2)

#include<iostream>
#include<windows.h>
using namespace std;


class Parents
{
    public:
        virtual void   vir_func(char a='x',char b='y',char c='z'); //虚函数
         Parents();
        ~Parents();                                    
};

void Parents::vir_func(char a,char b,char c)
{
    cout<<"父类的vir_func函数正在运行..."<<"参数为："<<a<<","<<b<<","<<c<<endl;

}
Parents::Parents()
{  
    cout<<"父类的构造函数正在运行..."<<endl;
    
}

Parents::~Parents()
{}

class Child:public Parents
{
public:
      ~Child();
      Child(int a,char c);
};
Child::Child(int i,char c)
{
    cout<<"子类的构造函数正在运行..."<<"参数为："<<i<<","<<c<<endl;

}
Child::~Child()
{}


class B
{
public:
    Parents *Par;
    void Init();
};
void B::Init()
{
    //父类指向子类
    Par=new Child(2,'c');
    cout<<"基类类型的指针已经绑定到派生类..."<<endl;
    Par->vir_func('d','e','f');
}

int main()
{
    
    B Test;
    Test.Init();
    system("pause");
    return 0;
}

#include<iostream>
#include<windows.h>
using namespace std;


class Parents
{
    public:
        virtual void   vir_func(char a='x',char b='y',char c='z'); //虚函数
         Parents();
        ~Parents();                                    
};

void Parents::vir_func(char a,char b,char c)
{
    cout<<"父类的vir_func函数正在运行..."<<"参数为："<<a<<","<<b<<","<<c<<endl;

}
Parents::Parents()
{  
    cout<<"父类的构造函数正在运行..."<<endl;
    
}

Parents::~Parents()
{}

class Child:public Parents
{
public:
     void vir_func(char a,char b,char c);
      ~Child();
      Child(int a,char c);
};
void Child::vir_func(char a,char b,char c)
{
    cout<<"子类的vir_func函数正在运行..."<<"参数为："<<a<<","<<b<<","<<c<<endl;
}
Child::Child(int i,char c)
{
    cout<<"子类的构造函数正在运行..."<<"参数为："<<i<<","<<c<<endl;

}
Child::~Child()
{}


class B
{
public:
    Parents *Par;
    void Init();
};
void B::Init()
{
    //父类指向子类
    Par=new Child(2,'c');
    cout<<"基类类型的指针已经绑定到派生类..."<<endl;
    Par->vir_func('d','e','f');
}

int main()
{
    
    B Test;
    Test.Init();
    system("pause");
    return 0;
}

从上面的2段程序可以看出：

当基类动态绑定到派生类时，如果派生类没有实现基类的虚函数，那么调用的是基类自己实现的虚函数。

若派生类重新定义虚函数，那么执行的则是派生类实现的虚函数。