1. 车辆基本信息管理 问题场景描述如下： 为了对车量基本信息进行管理，对现实世界车量基本信息抽象后，抽象出Car类、ElectricCar类、Battery类， 它们之间的关系描述如下：基于Car类派生出ElectricCar类，派生类ElectricCar中新增数据成员为Battery类 对象。

/*代码如下*/

#ifndef BATTERY_H#define BATTERY_Hclass battery {    private:        int batterysize;    public:        battery(int bs0=70):batterysize(bs0){}        void get_batterysize(); }; #endif // !BATTERY_H

#include"battery.h"#include
      
       using namespace std;void battery::get_batterysize(){    cout << batterysize << "-KWH";}
      

#ifndef CAR_H#define CAR_H#include
      
       using namespace std;class car {  private:      string maker;      string model;     int year;     double odometer;     double sum_meters = 100000.0; public:     car(string maker0, string model0, int year0, double odometer0 = 0.0) :maker(maker0), model(model0), year(year0), odometer(odometer0) {}     car(){}     friend ostream & operator<<(ostream &out, const car &c);//重载<
      

#include"car.h"#include
      
       #include
       
        using namespace std;void car::update_odometer(double meters) {    double odometer1 = odometer;     odometer1 += meters;     if (odometer > odometer1)        {         cout << "WARNING,更新数据失败" << endl;        }     else odometer = odometer1; }ostream & operator<<(ostream &out,const car &c) //重载实现{     cout << "汽车制造商：" << c.maker << endl         << "汽车型号：" << c.model << endl         << "生产年份：" << c.year << endl         << "总里程数：" << c.odometer << "km" << endl;     return out; }
       
      

#ifndef ELECTRICCAR_H#define ELECTRICCAR_H#include"car.h"#include"battery.h"#include
      
       #include
       
        using namespace std; class electricCar :private car, private battery { private:     battery b;//新增成员 public:     electricCar(string maker0, string model0, int year0, double odometer0 = 0.0, battery b0 = 70) :b(b0), car(maker0, model0, year0, odometer0) {}     friend ostream & operator<<(ostream &out, electricCar &e);//<
       
      

#include"electricCar.h"#include
      
       #include
       
        using namespace std;void electricCar::update_odometer(double meters) {    car::update_odometer(meters);//调用派生类的成员函数 } ostream & operator<<(ostream &out, electricCar &e) {
    //<
       
      

#include 
      
       #include
       
        using namespace std;#include "car.h"#include "electricCar.h"#include  
        
         int main() {    // 测试Car类         car oldcar("Audi", "a4", 2016);              cout << "--------oldcar's info--------" << endl;     oldcar.update_odometer(25000);     cout << oldcar << endl;     // 测试ElectricCar类     electricCar newcar("Tesla", "model s", 2016);     cout << "\n--------newcar's info--------\n";     newcar.update_odometer(2500);     cout << newcar << endl;     system("pause");     return 0; }
        
       
      

2、重载运算符[]为一维动态整形数组类ArrayInt的成员函数，使得通过动态整形数组对象名和下标可以 访问对象中具体元素。 

/*代码如下*/

#ifndef ARRAYINT_H#define ARRAYINT_Hclass ArrayInt{    public:        ArrayInt(int n, int value=0);        ~ArrayInt();        // 补足:将运算符[]重载为成员函数的声明        int& operator[](int i);         void print();     private:         int *p;         int size; };#endif // ARRAYINT_H

#include "arrayint.h"#include 
      
       #include 
       
        using std::cout;using std::endl;ArrayInt::ArrayInt(int n, int value): size(n) {    p = new int[size];//动态内存分配     if (p == nullptr) {
    //关于null、nullptr的使用另附         cout << "fail to mallocate memory" << endl;         exit(0);     }     for(int i=0; i
       
      

#include 
      
       using namespace std;#include "arrayInt.h"#include
       
        int main() {    // 定义动态整型数组对象a，包含2个元素，初始值为0    ArrayInt a(2);    a.print();         // 定义动态整型数组对象b，包含3个元素，初始值为6     ArrayInt b(3, 6);     b.print();          // 通过对象名和下标方式访问并修改对象元素     b[0] = 2;     cout << b[0] << endl;     b.print();     system("pause");     return 0; }
       
      

?????是我的codeblocks版本太老了吗，好像不支持这个标准

其他的IDE就可以运行

 二：实验总结与体会

1.怎样在派生类中引用基类的友元函数卡了，查资料得知。

2.派生类和重载不熟练，常常需要翻书。。

3.关于那个nullptr的问题

https://www.cnblogs.com/yutongqing/p/6508327.html

似乎在这里能找到一些头绪。

                             ----X.Raven