C++基础09-货物售卖和MyArray实现

1、货物出货与进货

#if 0
#include<iostream>
using namespace std;
/*
某商店经销一种货物。货物购进和卖出时以箱为单位。各箱
的重量不一样，因此商店需要记录目前库存的总重量，现在用
C++模拟商店货物购进和卖出的情况
*/
class Goods {
public:
	Goods() {
		weight = 0;
		next = NULL;
		cout << "创建了一个重量为：" << weight << "的货物" << endl;
	}
	Goods(int w) {
		//需要创建一个w的货物，并且仓库加这个重量
		weight = w;
		next = NULL;
		total_weight += w;
		cout << "创建了一个重量为：" << weight << "的货物" << endl;
	}
	static int get_total_wight() {
		return total_weight;
	}
	~Goods() {
		//需要删除一个w的货物，并且仓库减这个重量
		cout << "删除了一个重量为：" << weight << "的货物" << endl;
		total_weight -= weight;
	}
public:
	Goods *next;
private:
	int weight;
	static int total_weight;
};
int Goods::total_weight = 0;
void buy(Goods *&head, int w) {
	//创建一个货物 重量为w
	Goods *new_goods = new Goods(w);
	if (head == NULL)
		head = new_goods;
	else {
		new_goods->next = head;  //头结点插入
		head = new_goods;
	}
}
void sale(Goods * &head) {
	if (head == NULL) {
		cout << "仓库为空" << endl;
		return;
	}
	Goods *temp = head;
	head = head->next;
	delete temp;
	cout << "saled." << endl;
}
int main(void) {
	int choice = 0;
	int w;
	Goods *head = NULL;  //利用链表管理 无头指针
	do
	{
		cout << "1 进货" << endl;
		cout << "2 出货" << endl;
		cout << "0 退出" << endl;
		cin >> choice;
		switch (choice)
		{
		case 1:
			cout << "请输入要创建货物的重量" << endl;
			cin >> w;
			buy(head, w);
			break;
		case 2:
			sale(head);
			break;
		case 0:
			return 0;
			break;
		default:
			break;
		}
		cout << "当前仓库的总重量是：" <<Goods::get_total_wight()<< endl;
	} while (1);
}
#endif

我的思路：

#if 0
#include<iostream>
using namespace std;
/*
某商店经销一种货物。货物购进和卖出时以箱为单位。各箱
的重量不一样，因此商店需要记录目前库存的总重量，现在用
C++模拟商店货物购进和卖出的情况
*/
class Goods {
public:
	Goods(int num, int weight) {
		m_num = num;
		m_weight = weight;
	}
	void get_in_good() {
		
		m_sum_weight += m_num*m_weight;
	}
	void get_out_good(int num, int weight) {
		m_sum_weight -= num*weight;
	}
	static int get_m_sum_weight(){
		return m_sum_weight;
	}
private:
	int m_num;
	int m_weight;
	static int m_sum_weight;
};
int Goods::m_sum_weight = 0;
int main() {
	Goods g1(1, 20);
	Goods g2(2, 30);
	Goods g3(3, 50);
	g1.get_in_good();
	g2.get_in_good();
	g3.get_in_good();
	g2.get_out_good(1, 30);
	cout << Goods::get_m_sum_weight() << endl;
	return 0;
}
#endif

2、数组类的封装

MyArray.h

#pragma once
#include<iostream>
using namespace std;
class MyArray
{
public:
	friend ostream& operator<<(ostream& os, const MyArray &obj);
	friend istream& operator>>(istream& os, MyArray &obj);
	friend bool operator==(const MyArray &a1, const MyArray& a2);  //全局函数
	bool operator!=(const MyArray& another);  //成员函数
	MyArray();
	MyArray(int length);
	MyArray(const MyArray &obj);
	MyArray& operator=(const MyArray &obi);
	int& operator[](int index) const; 
	void setData(int index, int value);
	int getData(int index);
	int getLength() const;
	~MyArray();
private:
	int m_length;
	int *m_space;  //指向堆上空间 数组首地址
};

MyArray.cpp

#include "MyArray.h"

MyArray::MyArray() {
	cout << "MyArray()" << endl;
	m_length = 0;
	m_space = NULL;
}
MyArray::MyArray(int length){
	/*if (length < 0)
	{
		m_length = 0;
		m_space = new int[length];
	}
	else {
		m_length = length;
		m_space = new int[length];
	}*/
	//等价于
	if (length < 0)
	{
		length = 0;
	}
		m_length = length;
		m_space = new int[length];
}
MyArray::MyArray(const MyArray &obj) {
	if (obj.m_length>=0)
	{ 
		if (m_space != NULL) {
			delete[] m_space;
			m_space = NULL;
		}
		this->m_length = obj.m_length;
		this->m_space = new int[this->m_length];
		for (int i = 0; i < m_length; i++) //数据元素深拷贝
		{
			this->m_space[i] = obj.m_space[i];
		}
	}
}
MyArray::~MyArray() {
	if (m_space != NULL) {
		delete[] m_space;
		m_space = NULL;
	}
}
MyArray& MyArray::operator=(const MyArray &another) {
	if (this == &another)
	{
		return *this;
	}
	if (this->m_space != NULL) {
		delete this->m_space;
		this->m_space = NULL;
		this->m_length = 0;
	}
	if (another.m_length >= 0)
	{
		this->m_length = another.m_length;
		this->m_space = new int[this->m_length];
		for (int i = 0; i < m_length; i++) //数据元素深拷贝
		{
			this->m_space[i] = another.m_space[i];
		}
	}
	return *this;
}
int& MyArray::operator[](int index) const{
	return this->m_space[index];
}

void MyArray::setData(int index, int value) {
	if (m_space != NULL) {
		//a1.setData(i, i);
		m_space[index] = value;
	}
	
}
int MyArray::getData(int index) {
	return m_space[index];
}
int MyArray::getLength() const {
	return m_length;
}
bool MyArray::operator!=(const MyArray& another) {
	/*if (this->getLength() != another.getLength()) {
		return true;
	}
	for (int i = 0; i < this->getLength(); i++) {
		if (this->m_space[i] != another.m_space[i])
			return true;
	}
	return false;*/
	//等价于
	return !(*this == another);
}
ostream& operator<<(ostream& os, const MyArray &obj) { //防止被修改添加const后报错
			//原因分析：在调用getLengt()传入的是&obj,并不是const类型
		        //安全性高的转换为安全性低的会报错
			//下面的operator[](&obj)传入的是&obj,并不是const类型 所以报错
			//修改方法就是加上在getLength() 函数后添加const
			//修改方法就是加上在operator[](int index)函数后添加const
	os << "遍历整个数组" << endl;
	//for (int i = 0; i <obj.m_length; i++)  无法修改
	for (int i = 0; i <obj.getLength(); i++)
	{
		//os << obj.m_space[i] << " ";
		//等价于
		os << obj[i] << " ";
	}
	return os;
}
//istream& operator >> (istream& is,MyArray &obj) {
//	cout << "请输入数组元素个数：";
//	cin >> obj.m_length;
//	obj.m_space = new int[obj.m_length];
//	for (int i = 0; i < obj.m_length; i++)
//	{
//		int j;
//		cin >> j;
//		obj.m_space[i] = j;
//	}
//	return is;
//
//}
istream& operator>>(istream& is, MyArray &array) {
	cout << "请输入：" << array.getLength() << "个数" << endl;
	for (int i = 0; i < array.getLength(); i++)
	{
		cin >> array[i];
	}
	return is;
}
bool operator==(const MyArray &a1, const MyArray& a2) {
	if (a1.getLength() != a2.getLength()) {
		return false;
	}
	for (int i = 0; i < a1.getLength(); i++)
	{
		if (a1.m_space[i] != a2.m_space[i])
			return false;
	}
	return true;
}

main.cpp

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


int main() {
	MyArray a1(10);
	for (int i = 0; i < a1.getLength(); i++)
	{
		//a1.setData(i, i);
		a1[i] = i + 10;  //space[i]=i+10
	}
	cout << "print a1" << endl;
	for (int i = 0; i < a1.getLength(); i++)
	{
		//cout<<a1.getData(i)<<"  ";
		cout << a1[i] << " " ;
	}
	MyArray a2 = a1;
	cout << endl<<"print a2" << endl;
	for (int i = 0; i < a2.getLength(); i++)
	{
		//cout<<a1.getData(i)<<" ";
		cout << a2[i] << " " ;
	}
	cout << endl;
	MyArray a3;
	a3 = a1;
	cout << endl << "print a3" << endl;
	for (int i = 0; i < a3.getLength(); i++)
	{
		//cout << a3.getData(i) << " ";
		cout << a3[i] << " " ;
	}
	cout <<endl<< "<<操作符重载" << endl;
	cout << a3 << endl;

	MyArray array1(3);
	cin >> array1;
	cout << array1 << endl;

	if (array1 == a1) {
		cout << "相等" << endl;
	}
	else
		cout << "不相等" << endl;

	if (array1 != a1) {
		cout << "不相等" << endl;
	}
	else
		cout << "相等" << endl;
}