C++Note 同名静态成员处理 继承语法

class Base
{
public:
    static int m_A;// 静态成员 类名声明 类外初始化
};
int Base::m_A = 100;
class Son :public Base
{
public:
    static int m_A;
};
int Son::m_A = 200;
//同名静态成员属性
void test()
{
    //1.通过对象访问
    cout << "通过对象的访问" << endl;
    Son s;
    cout << " Son  m_A = " << s.m_A << endl;
    cout << " Base  m_A = " << s.Base::m_A << endl;
    //2.通过类名访问
    cout << "通过类名的访问" << endl;
    cout << " Son  m_A = " << Son::m_A << endl;
    cout << " Base  m_A = " << Base::m_A << endl;
    cout << " 通过Son继承Base  m_A = " << Son::Base::m_A << endl;
    //第一个::代表类名访问  第二个::代表访问父类作用域下
}

函数访问

//继承中同名静态函数
class Base
{
public:
    static void func()
    {
        cout << "Base - static void func()" << endl;
    }
    static void func(int a)
    {
        cout << "Son - static void func(int a)" << endl;
    }
};
class Son :public Base
{
public:
    static void func()
    {
        cout << "Son - static void func()" << endl;
    }
    
};

void  test1()
{
    //通过对象访问
    cout << "通过对象访问" << endl;
    Son s;
    s.func();
    s.Base::func();
    //通过类名访问
    cout << "通过类名访问" << endl;
    Son::func();
    Son::Base::func();
    //Son::func(100);//错误 函数因为同名被隐藏
    Son::Base::func(110);//正确 需要加作用域继承
}

C++允许一个类继承多个类

语法：class 子类:继承方式 父类1,继承方式 父类2...

多继承可能会引发父类中有同名成员出现 需要加作用域区分

C++实际开发中不建议用多继承

class Base1
{
public:
    Base1()
    {
        m_A = 100;
    }
    int m_A;
};
class Base2
{
public:
    Base2()
    {
        m_A = 100;
    }
    int m_A;
};
//子类继承Base1和Base2
//语法:class 子类:继承方式 父类1,继承方式 父类2...
class Son :public Base1,public Base2
{  
public:
    Son()
    {
        m_C = 300;
        m_D = 400;
    }
    int m_C;
    int m_D;
};
void test()
{
    Son s;
    cout << "sizeof = " << sizeof(s) <<endl;//16 自身两个整型 继承 1 2 共4个整型
    //当父类中出现同名成员,需要加作用域区分
    cout << "Base1::m_A = " << s.Base1::m_A << endl;
    cout << "Base2::m_A = " << s.Base2::m_A << endl;
}