实验四

Posted 2021-11-30 qiuqiuwr

题一：

#ifndef BATTERY_H
#define BATTERY_H
class Battery {
public:
    Battery(int x = 70);
    int getbattery()const;
private:
    int batterySize;
   };

#endif

battery.h

#ifndef CAR_H
#define CAR_H
#include<string>
#include<iostream>
using namespace std;
class Car{
public:
    Car(string maker1,string model1,int year1,int odometer1=0) :maker(maker1), model(model1), year(year1), odometer(odometer1) {}
    friend ostream& operator<<(ostream &out,Car &c);
    void updateOdometer(int  number);
    string maker;
    string  model;
    int year;
    int  odometer;     
    
};
#endif

car.h

#ifndef ELECTRICCAR_H
#define ELECTRICCAR_H

#include"car.h"
#include"battery.h"
#include<string>
#include<iostream>
class ElectricCar:public Car,public Battery{
public:
    ElectricCar(string maker2, string model2, int year2, int odometer2 = 0) :Car(maker2, model2, year2, odometer2) {
    }

    friend ostream& operator<<(ostream &outCar,ElectricCar &d);
    void updateOdometer(int  number);
private:
    Battery battery;
};
#endif

electricCar.h

#include"Battery.h"
Battery::Battery(int x)
{batterySize=x; }
int Battery::getbattery()const 
{
return   batterySize;
}

battery.cpp

#include<iostream>
#include<string>
#include "Car.h"
using namespace std;
void  Car:: updateOdometer(int  number)
{
    if(number<odometer)
        cout<<"the new odometer is wrong!"<<endl;
    else
        odometer=number;
}
ostream& operator<<(ostream &out,Car &c)
{
    out<<c.maker<<endl<<c.model<<endl<<c.year<<endl<<c.odometer<<endl;
    return out;
}

car.cpp

#include"electricCar.h"
#include<iostream>
using namespace std;

ostream& operator<<(ostream &out,ElectricCar &d)
{
    out<<d.maker<<endl<<d.model<<endl<<d.year<<endl<<d.odometer<<endl;
    return out;
}
void   ElectricCar::updateOdometer(int  number)
{
    if (number < odometer)
        cout << "the new odometer is wrong!" << endl;
    else
        odometer = number;
}

electricCar.cpp

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

main.cpp

运行截图

题目二：

#ifndef ARRAY_INT_H
#define ARRAY_INT_H
class ArrayInt{
public:
ArrayInt(int n, int value=0);
~ArrayInt();
int &operator[](int x); 
void print();
private:
int *p;
int size;
};
#endif

arrayInt.h

#include "arrayInt.h"
#include <iostream>
#include <cstdlib>
using std::cout;
using std::endl;
ArrayInt::ArrayInt(int n, int value): size(n) {
p = new int[size];
if (p == NULL) {
cout << "fail to mallocate memory" << endl;
exit(0);
}
for(int i=0; i<size; i++)
p[i] = value;
}
ArrayInt::~ArrayInt() {
delete[] p;
}
void ArrayInt::print() {
for(int i=0; i<size; i++)
cout << p[i] << " ";
cout << endl;
}
int& ArrayInt:: operator[](int x)
{
    return p[x];
}

arrayInt.cpp

#include <iostream>
using namespace std;

#include "arrayInt.h"

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;
}

Main.cpp

 实验总结：

1.在写第一道题时，起初在定义car类之前没有使用ifndef def语句，导致了Car类的重定义，应该是C++标准类中有Car类了，浪费了一些时间。

2.之前没有明白运算符重载是怎么实现参数传递的，后来想明白了，就和函数一样。

3.第一道题中分别需要Car类带默认形参值的构造函数和ElectricCar类带默认形参值的构造函数，一开始没考虑太多，直接写了两个构造函数，编译时出错了，因为ElectricCar继承了Car类，有两个构造函数，计算机不知道选哪个，后来作了一些改动。当然不止一种解决办法，虚基类应该也可以解决。