实验4

1、车辆类的实现

battery.h

#ifndef BATTERY_H
#define BATTERY_H
class Battery
{
public:
 Battery(int a=70);
 int getbatterysize();
private:
 int batterysize;
};
#endif

battery.cpp

#include"battery.h"
#include<iostream>
Battery::Battery(int a=70):batterysize(a){};
int Battery::getbatterysize(){
 return batterysize;
}

car.h

#ifndef CAR_H
#define CAR_H
#include<iostream>
using std::string;
using std::ostream;
class Car{
public:
 Car(string a,string b,int c,double d=0){};
 friend ostream& operator<<(ostream &out,const Car &c);
 void updateOdometer(double e);
 string getmaker() const;
 string getmodel() const;
 int getyear() const;
 double getodometer() const;
private:
 string maker;
 string model;
    int year;
 double odometer;
};
#endif

car.cpp

#include"car.h"
#include<iostream>
#include<string>
using namespace std;
Car::Car(string a,string b,int c,double d=0){
      maker=a;
   model=b;
   year=c;
   odometer=d;
}
ostream &operator<<(ostream &out,const Car &c){
 out<<"maker:"<<c.maker<<endl<<"model:"<<c.model<<endl<<"year:"<<c.year<<endl<<"odometer:"<<c.odometer<<endl;
 return out;
}
void Car::updateOdometer(double e){
 if(e>=odometer)
 odometer=e;
 else
 cout<<"wrong"<<endl;
}
string Car::getmaker() const
{
 return maker;
}

string Car::getmodel() const
{
 return model;
}

int Car::getyear() const
{
 return year;
}

double Car::getodometer() const
{
 return odometer;
}

 electriccar.h

#ifndef ELECTRICCAR_H
#define ELECTRICCAR_H
#include"car.h"
#include"battery.h"
#include<iostream>
using std::string;
using std::ostream;
class ElectricCar:public Car,public Battery{
public:
 ElectricCar(string a,string b,int c,double d=0,int e=70){};
 friend ostream& operator<<(ostream &out,const Car &c);
private:
 Battery battery;
};
#endif

electriccar.cpp

#include"electricCar.h"
#include<iostream>
#include"battery.h"
#include"car.h"
using namespace std;
ostream &operator<<(ostream &out,const ElectricCar &c){
 out<<"maker:"<<c.getmaker<<endl<<"model:"<<c.getmodel<<endl<<"year:"<<c.getyear<<endl<<"odometer:"<<c.getodometer<<endl<<"battery:"<<c.getbatterysize<<endl;
 return out;
}
ElectricCar::ElectricCar(string a, string b, int c, double d = 0,int e) :Car(a, b, c, d),battery(e) {};

main.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;
}

2、重载【】

arrayint.h

#ifndef ARRAY_INT_H
#define ARRAY_INT_H

class ArrayInt{
 public:
  ArrayInt(int n, int value=0);
  ~ArrayInt();
  int &operator[](int i);
  void print();
 private:
  int *p;
  int size;
};

#endif

arrayint.cpp

#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;
}

int  &ArrayInt::operator[](int i) {
 return p[i];
}

main.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;
}

实验总结：第一个车辆类仍有许多未曾完善的地方，写的时候也花了很多不必要的时间。

第二个动态数组类理解起来更为容易，想较于以前的数组定义更简单明了。

总之还是需要多加强对运算符重载的练习以及对类的感觉。