C++子类继承父类

（1）基类的静态成员函数和静态数据成员都可以被继承。

#include <iostream>
#include <string>

using namespace std;

class People
{
public:
    People() {}
    ~People() {}
    static void show(void);
    static int tall;
};

void People::show(void)
{cout << "The peole!" << endl;}

int People::tall = 170;

class Student : public People
{
    public:
    void gotoSchool(void) {cout << "Go to school!" << endl;}
};

int main(int argc, char *argv[])
{
    Student Jack;
    Jack.gotoSchool();
    Student::show();
    cout << Student::tall << endl;

    return 0;
}

（2）友元函数不可以被继承。

#include <iostream>
#include <string>

using namespace std;

class People
{
public:
    People() : tall(0) {}
    ~People() {}

    friend void showInfo(const People& p)
    {cout << "The tall: " << p.tall << endl;}
    static void show(void);
private:
    int tall;
};

class Student : public People
{};

int main(int argc, char *argv[])
{
    Student Jack;
    showInfo(Jack);  // 这里友元函数访问了派生类对象

    return 0;
}

（3）友元类可以不被继承