[C++知识库]静态绑定与动态绑定

静态绑定与动态绑定

• 静态绑定：编译阶段完成。成员函数重载以及派生类对基类的重载就是静态绑定。发生调用时由参数类型决定，与指向对像无关。

class static_binding
{
public:
    void play()
    {
        printf("static_binding play()\n");
    }
};

class static_binding_child : public static_binding
{
public:
    void play()
    {
        printf("static_binding_child play()\n");
    }
};

void show(static_binding &sb)
{
    sb.play();
}

int main(int argc, char *argv[])
{
    static_binding sb;
    static_binding_child sbc;
    show(sb);       //static_binding play()
    show(sbc);      //static_binding play()
    return 0;
}

• 动态绑定：运行时完成。能动态地根据指针或引用对象的实际类型来选择调用的函数。通常用虚函数实现。

class dynamic_binding
{
public:
    virtual void play()
    {
        printf("dynamic_binding play()\n");
    }
};

class dynamic_binding_child : public dynamic_binding
{
public:
    void play()
    {
        printf("dynamic_binding_child play()\n");
    }
};

void show(dynamic_binding &db)
{
    db.play();
}

int main(int argc, char *argv[])
{
    dynamic_binding db;
    dynamic_binding_child dbc;
    show(db);       //dynamic_binding play()
    show(dbc);      //dynamic_binding_child play()
    dynamic_binding *pdb = &dbc;
    show(*pdb);     //dynamic_binding_child play()
    dynamic_binding_child *pdbc = (dynamic_binding_child *)&db;
    show(*pdbc);    //dynamic_binding play()
    return 0;
}