C++Primer 第15章 OOP

#include<iostream> class Base { public:virtual void fun1(int i = 0){std::cout << i << std::endl;} private:int a = 0; };class Son :public Base { public:virtual void fun1(int i = 9) override final{std::cout << i << std::endl;}//fun2沒有繼續基類不能使用override//virtual void fun2(int i = 10) override//{// std::cout << i << std::endl;//}virtual void fun3(int i = 3){std::cout << i << std::endl;}private:};class Grandson :public Son { public://這里的函數因為其基類的該函數使用了final所以不能被覆蓋//virtual void fun1(int i = 9) override final //{// std::cout << i << std::endl;//} private:};int main() {Base b;b.fun1(10);Son s;s.fun1();//s.a; 不可訪問基類的私有成員。Grandson gs;//這里調用Son的fun3，且需要為public繼承，函數成員也應當為publicgs.fun3();//顯式的執行其基類Base的函數fun1，public繼承可以實現向上的轉換調用gs.Base::fun1();std::cout << 0xE800 << std::endl; }#include<iostream> #include<string> using namespace std;class Base { public:virtual void public_fun() { cout << "base public_fun" << endl; }string public_val{ "public_val" };protected:virtual void protected_fun(){ cout << "base protected_fun" << endl; }string protected_val{ "protected_val" };private:virtual void private_fun(){ cout << "base private_fun" << endl; }string private_val{ "private_val" }; };//對于成員來說，成員的訪問級別與類的繼承方式無關 class Public_son :public Base { public:string getpublic() { return public_val; }string getprotected() { return protected_val; }//int getprivate() { return private_val; } //不可訪問私有成員 public:virtual void public_fun() { cout << "Public_son public_fun" << endl; } protected:virtual void protected_fun() { cout << "Public_son protected_fun" << endl; } private:virtual void private_fun() { cout << "Public_son private_fun" << endl; } };class Protected_son :protected Base { public:string getpublic() { return public_val; }string getprotected() { return protected_val; }//int getprivate() { return private_val; } //不可訪問私有成員 public:virtual void public_fun()override { cout << "Protected_son public_fun" << endl; } protected:virtual void protected_fun()override { cout << "Protected_son protected_fun" << endl; } private:virtual void private_fun()override { cout << "Protected_son private_fun" << endl; } };class Private_son :private Base { public:string getpublic() { return public_val; }string getprotected() { return protected_val; }//int getprivate() { return private_val; } //不可訪問私有成員 public:virtual void public_fun()override { cout << "Private_son public_fun" << endl; } protected:virtual void protected_fun()override { cout << "Private_son protected_fun" << endl; } private:virtual void private_fun()override { cout << "Private_son private_fun" << endl; } };int main() {Base base;Public_son public_son;Protected_son protected_son;Private_son private_son;/***Public_son成員***///調用Base數據cout << public_son.public_val << endl;//cout < public_son.protected_val << endl; //不可訪問//cout << public_son.private_val << endl; //不可訪問//顯式Base調用數據cout << public_son.Base::public_val << endl;//cout << public_son.Base::protected_val << endl; //不可訪問//cout << public_son.Base::private_val << endl; //不可訪問//調用函數public_son.public_fun();public_son.Base::public_fun();//其他均不行/***Protected_son成員，調用Base數據***///cout << protected_son.public_val << endl; //不可訪問//cout < protected_son.protected_val << endl; //不可訪問//cout << protected_son.private_val << endl; //不可訪問//顯式調用Base的相應數據//cout << protected_son.Base::public_val << endl; //不允許類型轉換//cout << protected_son.Base::protected_val << endl; //不可訪問//cout << protected_son.Base::private_val << endl; //不可訪問//調用函數protected_son.public_fun();//protected_son.Base::public_fun(); //不允許類型轉換/***Private_son成員，調用Base數據***///cout << private_son.public_val << endl; //不可訪問//cout < private_son.protected_val << endl; //不可訪問//cout << private_son.private_val << endl; //不可訪問//顯式調用Base的相應數據//cout << private_son.Base::public_val << endl; //不允許類型轉換//cout << private_son.Base::protected_val << endl; //不可訪問//cout << private_son.Base::private_val << endl; //不可訪問//調用函數private_son.public_fun(); }

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