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1. Deep copy and shallow copy
The core difference between deep copy and shallow copy:
Shallow copy: Copy the address of a variable, which is equivalent to pointing to the same storage space.
Deep copy: copying the contents of a variable is equivalent to creating a new one with the same contents.
#include<iostream>
#include<string>
#include"Date.h"
#include"Employee.h"
//任务1:构造Employee对象e1,拷贝构造e2
//任务2:调式模式观察e1和e2的biethday成员
//任务3:添加拷贝构造函数实现深拷贝
//任务4:调试模式观察e1和e2的birthday成员
int Employee::numberOfObjects = 0;
int main()
{
Employee e1{
"Alex",Gender::male,{
1998,5,1} };
Employee e2{
e1 };
std::cout << e1.toString() << std::endl;
std::cout << e2.toString() << std::endl;
std::cin.get();
return 0;
}
#pragma once
//任务1：定义Date类
#include<iostream>
#include<string>
class Date
{
private:
int year = 2019, month = 1, day = 1;
public:
int getYear() {
return year; }
int getMonth() {
return month; }
int getDay() {
return day; }
void setYear(int y) {
year = y; }
void setMonth(int m) {
month = m; }
int setDay(int d) {
day = d; }
Date() = default;
Date(int y, int m, int d) :year{
y }, month{
m }, day{
d }
{
std::cout << "Data" << toString() << std::endl;
}
std::string toString()
{
return (std::to_string(year) + "-" + std::to_string(month) + "-" + std::to_string(day));
}//2019-1-1
};
#pragma once
//任务2:定义Gender枚举类型
//任务3:定义Employee类
#include<iostream>
#include<string>
#include"Date.h"
enum class Gender
{
male,
female,
};
class Employee
{
private:
std::string name;
Gender gender;
Date* birthday;
static int numberOfObjects;
public:
void setName(std::string name) {
this->name = name; }
void setGender(Gender gender) {
this->gender = gender; }
void setBirthday(Date birthday) {
*(this->birthday)= birthday; }
std::string getName() {
return name; }
Gender getGender() {
return gender; }
Date getBirthday() {
return *birthday; }
std::string toString()
{
return (name + (gender == Gender::male ? std::string("male") : std::string("female")) + birthday->toString());
}
Employee(std::string name, Gender gender, Date birthday) :name{
name }, gender{
gender }
{
numberOfObjects++;
this->birthday=new Date{
birthday };
std::cout << "Now there are: " << numberOfObjects << "employee" << std::endl;
};
Employee() :Employee("Alan", Gender::male, Date(2000, 4, 1)) {
}
Employee(const Employee& e) //深拷贝函数 存在 则调用时为深拷贝
{
this->birthday = new Date{
*(e.birthday) };
numberOfObjects++;
}
~Employee()
{
numberOfObjects--;
delete birthday;
birthday = nullptr;
}
};
The result is shown above.