1.車輛基本信息管理

battery.h

 1 #ifndef BATTERY_H
 2 #define BATTERY_H
 3 class Battery
 4 {
 5 public:
 6     Battery(int p=70):batterySize(p){}
 7     int showbatterySize();
 8 private:
 9     int batterySize;
10 };
11 #endif // BATTERY_H

battery.cpp

1 #include "battery.h"
2 
3 int Battery::showbatterySize()
 
4 {
5     return batterySize;
6 }

car.h

 1 #ifndef CAR_H
 2 #define CAR_H
 3 #include <cstring>
 4 #include <iostream>
 5 using namespace std;
 6 class Car
 7 {
 8 public:
 9     Car (string maker1,string model1,int year1,int odometer1=0);
10     void updateOdometer(int update);
 
11     string showMaker();
12     string showModel();
13     int showYear();
14     int showOdometer();
15     friend ostream & operator<<(ostream &output,const Car &car1);
16 private:
17     string maker;
18     string model;
19     int year;
20     int odometer;
21 };
22
 
 #endif // CAR_H

car.cpp

 1 #include "car.h"
 2 #include <cstring>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 Car::Car(string maker1,string model1,int year1,int odometer1):
 7     maker(maker1),model(model1),year(year1),odometer(odometer1)
 8 {
 9 
10 }
11 void Car::updateOdometer(int update)
12 {
13     if(update<odometer)
14         cout<<"wrong updateodometer"<<endl;
15     else
16     {
17         odometer=update;
18     }
19 }
20 string Car::showMaker()
21 {
22     return maker;
23 }
24 string Car::showModel()
25 {
26     return model;
27 }
28 int Car::showYear()
29 {
30     return year;
31 }
32 int Car::showOdometer()
33 {
34     return odometer;
35 }
36 ostream &operator<<(ostream &output,const Car &car1)
37 {
38     output<<"maker"<<":"<<car1.maker<<endl
39     <<"model"<<":"<<car1.model<<endl
40     <<"year"<<":"<<car1.year<<endl
41     <<"odometer"<<":"<<car1.odometer<<endl;
42     return output;
43 }

electricCar.h

 1 #ifndef ELECTRICCAR_H
 2 #define ELECTRICCAR_H
 3 #include <iostream>
 4 #include "car.h"
 5 #include "battery.h"
 6 using namespace std;
 7 class electricCar:public Car,public Battery
 8 {
 9 public:
10     electricCar(string maker1,string model1,int year1,int odometer1=0);
11     friend ostream & operator<<(ostream &output,electricCar &electriccar1);
12 private:
13     Battery battery;
14 
15 };
16 #endif

electricCar.cpp

 1 #include "electricCar.h"
 2 #include <cstring>
 3 #include <iostream>
 4 using namespace std;
 5 electricCar::electricCar(string maker1,string model1,int year1,int odometer1):
 6    Car(maker1,model1,year1,odometer1),battery(70)
 7 {
 8 
 9 }
10 ostream &operator<<(ostream &output,electricCar &electriccar1)
11 {
12      output<<"maker"<<":"<<electriccar1.showMaker()<<endl
13     <<"model"<<":"<<electriccar1.showModel()<<endl
14     <<"year"<<":"<<electriccar1.showYear()<<endl
15     <<"odometer"<<":"<<electriccar1.showOdometer()<<endl
16     <<"batterySize"<<":"<<electriccar1.showbatterySize()<<"-kWh"<<endl;
17     return output;
18 }

main.cpp

 1 #include <iostream>
 2 #include <stdlib.h>
 3 using namespace std;
 4 
 5 #include "car.h"
 6 #include "electricCar.h"
 7 
 8 int main() {
 9     // 測試Car類
10     Car oldcar("Cheng nuo","knight4",2019);
11     cout << "--------oldcar‘s info--------" << endl;
12     oldcar.updateOdometer(25000);
13     cout << oldcar << endl;
14 
15     // 測試ElectricCar類
16     electricCar newcar("Tesla","model s",2016);
17     newcar.updateOdometer(2500);
18     cout << "\n--------newcar‘s info--------\n";
19     cout << newcar << endl;
20     newcar.updateOdometer(1500);
21     cout << "\n--------newcar‘s info--------\n";
22     cout << newcar << endl;
23 
24     system("pause");
25 
26     return 0;
27 }

更改了一些信息，並且在裏程數小於之前時會報錯

2.補足程序

arrayInt.h

 1 #ifndef ARRAY_INT_H
 2 #define ARRAY_INT_H
 3 
 4 class ArrayInt{
 5     public:
 6         ArrayInt(int n, int value=0);
 7         ~ArrayInt();
 8         // 補足:將運算符[]重載為成員函數的聲明
 9         // ×××
10         int &operator[](int point);
11         void print();
12     private:
13         int *p;
14         int size;
15 };
16 
17 #endif

arrayInt.cpp

 1 #ifndef ARRAY_INT_H
 2 #define ARRAY_INT_H
 3 
 4 class ArrayInt{
 5     public:
 6         ArrayInt(int n, int value=0);
 7         ~ArrayInt();
 8         // 補足:將運算符[]重載為成員函數的聲明
 9         // ×××
10         int &operator[](int point);
11         void print();
12     private:
13         int *p;
14         int size;
15 };
16 
17 #endif

main.cpp

 1 #include <iostream>
 2 #include <stdlib.h>
 3 using namespace std;
 4 
 5 #include "arrayInt.h"
 6 
 7 int main() {
 8     // 定義動態整型數組對象a，包含2個元素，初始值為0
 9     ArrayInt a(3);
10     a.print();
11 
12     // 定義動態整型數組對象b，包含3個元素，初始值為6
13     ArrayInt b(5, 4);
14     b.print();
15 
16     // 通過對象名和下標方式訪問並修改對象元素
17     b[3] = 5;
18     cout << b[3] << endl;
19     b.print();
20 
21     system("pause");
22 
23     return 0;
24 }

對main.cpp做了一些修改

實驗總結：

1.派生類的構造函數對派生類進行初始化時，要先將基類初始化，然後對成員對象初始化

2.重載<<運算符時，要註意引用符號的使用，並且要返回輸出流對象

3.由於繼承後的派生類在打印時無法調用基類的私有成員，所以要在基類中設置接口，使得能夠在派生類中輸出基類中私有成員的值

4.一個問題，友元函數operator<<中使用electriccar1.battery.showbatterySize()時，編譯器顯示battery為私有成員無法調用，但是友元函數不是可以訪問私有成員？

5.有關<<運算符重載時要註意頭文件iostream和using namespace std；要寫全

6.system("pause")要在前面加上#include<stdlib.h>

7.運算符[]重載時，返回值必須為引用類型，因為它作為左值不能為常量

c++第四次實驗