实验4 继承

任务二

未加virtual

加virtual之后

 

 

 同名覆盖原则:基类中的函数和派生类的函数重名时,若未强行指名,则通过派生类对象使用的是派生类的同名成员

二元作用域分辨符:当派生类与基类中有相同成员时,如果要通过派生类对象访问基类中被隐藏的同名成员,可以用基类名和作用域分辨符来限定

类型兼容原则:在需要基类对象的任何地方,都可以使用公有派生类的对象来替代。

派生类的对象可以隐含转换为基类对象

派生类的对象可以初始化基类的引用

派生类的指针可以隐含转换为基类的指针

通过基类对象名、指针只能使用从基类继承的成员。
 
任务三:
battery.hpp
 1 #ifndef _BATTERY_HPP_
 2 #define _BATTERY_HPP_
 3 #include<iostream>
 4 class Battery {
 5 private:
 6     int capacity;
 7 public:
 8     Battery(int c = 70): capacity(c){}
 9     int get_capacity() const {
10         return capacity;
11     }
12 };
13 
14 #endif

car.hpp

 1 #ifndef _CAR_HPP_
 2 #define _CAR_HPP_
 3 #include<iostream>
 4 #include<string>
 5 
 6 using namespace std;
 7 
 8 class Car {
 9 private:
10     string maker, model;
11     int year, odometers;
12 public:
13     Car(string maker1, string model1, int year1);
14     void info();
15     void update_odometers(int m);
16 };
17 
18 Car::Car(string maker1, string model1, int year1) :
19     maker(maker1), model(model1), year(year1) {
20     odometers = 0;
21 }
22 
23 void Car::info() { 
24     cout << "maker:       " << maker << endl;
25     cout << "model:       " << model << endl;
26     cout << "year;        " << year << endl;
27     cout << "odometers:   " << odometers << endl;
28 }
29 void Car::update_odometers(int m) {
30     if (m < odometers)
31         cout << "里程数更新失败!" << endl;
32     else
33         odometers = m;
34     return;
35 }
36 
37 #endif

electricCar.hpp

 1 #ifndef _ELECTRICCAR_HPP_
 2 #define _ELECTRICCAR_HPP_
 3 #include<iostream>
 4 #include"battery.hpp"
 5 #include"car.hpp"
 6 #include<string>
 7 
 8 class ElectricCar : public Car, public Battery {
 9 private:
10     Battery battery;
11 public:
12     ElectricCar(string maker1, string model1, int year1, int c = 70);
13     void info();
14 };
15 
16 ElectricCar::ElectricCar(string maker1, string model1, int year1, int c) :
17     Car(maker1, model1, year1), Battery(c) {}
18 
19 void ElectricCar::info() {
20     Car::info();
21     cout << "Capacity:    " << battery.get_capacity() << "-kWh" << endl;
22 }
23 
24 #endif

task3,cpp

 1 #include<iostream>
 2 #include"electricCar.hpp"
 3 int main() {
 4     using namespace std;
 5 
 6     Car oldcar("Audi", "a4", 2016);
 7     cout << "---------oldcar's info---------" << endl;
 8     oldcar.update_odometers(25000);
 9     oldcar.info();
10 
11     cout << endl;
12 
13     ElectricCar newcar("Tesla", "model s", 2016);
14     newcar.update_odometers(2500);
15     cout << "\n--------newcar's info---------\n";
16     newcar.info();
17 
18 }

实验结果截图:

 

任务四:

pets.hpp

 1 #ifndef _PETS_HPP_
 2 #define _PETS_HPP_
 3 #include<iostream>
 4 #include<cstring>
 5 using namespace std;
 6 
 7 class MachinePets {
 8 private:
 9     string nickname;
10 public:
11     MachinePets(const string s):nickname(s){}
12     virtual string talk() {
13         return "la la la";
14     }
15     string get_nickname() const {return nickname;}
16 }; 
17 
18 class PetCats : public MachinePets {
19 public:
20     PetCats(const string s):MachinePets(s){}
21     string talk() {
22         return "miao wu~";
23     }
24 };
25 
26 class PetDogs : public MachinePets {
27 public:
28     PetDogs(const string s) :MachinePets(s) {}
29     string talk() {
30         return "wang wang~";
31     }
32 };
33 
34 #endif

task4.cpp

 1 #include<iostream>
 2 #include"pets.hpp"
 3 
 4 void play(MachinePets * ptr) {
 5     std::cout << ptr->get_nickname() << " says " << ptr->talk() << std::endl;
 6 }
 7 
 8 int main() {
 9     PetCats cat("miku");
10     PetDogs dog("da huang");
11 
12     play(&cat);
13     play(&dog);
14 }

实验结果截图:

 

 

 

posted @ 2021-11-25 21:11  Xx0  阅读(1)  评论(0编辑  收藏  举报