实验四

1.

#ifndef BATTERY_H
#define BATTERY_H

class Battery {
public:
    Battery(int batterySize0 = 70);
        int showBattery();
private:
    int batterySize;
};

#endif

#include "battery.h"
Battery::Battery(int batterysize0):batterySize(batterysize0){
};
int Battery::showBattery() {
    return batterySize;
}

#ifndef CAR_H
#define CAR_H
#include <string>
#include <iostream>
using namespace std;

class Car {
public:
    Car(string a, string b, int y,int o=0);
    friend ostream&operator<<(ostream &out, Car &c);
    int updateOdometer(int x);
    string showmaker();
    string showmodel();
    int showyear();
    int showodometer();
private:
    string maker;
    string model;
    int year;
    int odometer;
};

#endif

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

Car::Car(string a, string b, int y,int o):maker(a),model(b),year(y),odometer(o) {
};
string Car::showmaker() {
    return maker;
}
string Car::showmodel() {
    return model;
}
int Car::showyear() {
    return year;
}
int Car::showodometer() {
    return odometer;
}
ostream &operator<<(ostream &out, Car &c) {
    out << "maker:" << c.maker << endl << "model:" << c.model << endl << "year:" << c.year << endl << "odometer:" << c.odometer << endl;
    return out;
}
int Car::updateOdometer(int x) {
    if (x < odometer)
        cout << "the new odometer is wrong" << endl;
    else
        odometer = x;
    return odometer;
}

#ifndef ELECTRICAR_H
#define ELECTRICAR_H
#include"battery.h"
#include"car.h"

class ElectricCar :public Car,public Battery{
public:
    ElectricCar(string a, string b, int y, int o=0);
    friend std::ostream & operator<<(std::ostream &out, ElectricCar &c);
private:
    int battery;
};

#endif

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

ElectricCar::ElectricCar(string a, string b, int y, int o) :Car(a, b, y, o) {
}
std::ostream &operator<<(std::ostream &out, ElectricCar &c) {
    out << "maker:" << c.showmaker() << endl << "model:" << c.showmodel() << endl << "year:" << c.showyear() << endl << "odometer:" << c.showodometer() << endl << "batterysize:" << c.showBattery() << "-kwh" << endl;
    return out;
}

#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;
}

 

2.

#ifndef ARRAY_INT_H
#define ARRAY_INT_H

class 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 a);
        void print(); 
    private:
        int *p;
        int size;
};

#endif

#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 == nullptr) {
        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;
}

// 补足:将运算符[]重载为成员函数的实现
// ×××
int &ArrayInt::operator[](int a){
    return p[a];
}

#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;
}

总结：对类的继承和派生还是有点生疏

           不怎么清楚operotar前为什么一定要加&