一、析构函数
#include<iostream>
#include<string>
//任务1：定义Date类
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
};
//任务2:定义Gender枚举类型
//任务3:定义Employee类
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()
{
numberOfObjects--;
delete birthday;
birthday = nullptr;
}
};
int Employee::numberOfObjects = 0;
//任务4:在堆和栈(函数作用域与内嵌作用域)上分别创建Employee对象，观察析构函数的行为
int main()
{
Employee e1;
std::cout << e1.toString() << std::endl;
Employee* e2 = new Employee{
"John",Gender::male,Date(19990,3,2) };
std::cout << e2->toString() << std::endl;
{
Employee e3{
"Alice",Gender::female,{
1989,2,14} };
std::cout << e3.toString() << std::endl;
}
std::cin.get();
return 0;
}
结果如上图所示。
二、拷贝构造
#include<iostream>
//任务1:创建Square类
class Square
{
private:
double side{
1.0 };
static int numberOfObjects;
public:
double getSide() {
return side; }
void setSide(double side) {
this->side = side; }
Square(double side)
{
this->side = side;
numberOfObjects++;
}
Square(const Square& s)
{
this->side = s.side;
numberOfObjects++;
std::cout << "Square(const Square&) is invoked" << std::endl;
}
~Square()
{
numberOfObjects--;
}
Square() :Square(1.0) {
}
double getArea() {
return side * side; }
static int getNumberOfObjects() {
return numberOfObjects; }
int getNumberOfObjectsNonStatic() {
return numberOfObjects; }
};
int Square::numberOfObjects = 0;
//任务4:在堆和栈上分别拷贝创建Square对象
int main()
{
Square s1(10.0);
std::cout << "Squares: " << Square::getNumberOfObjects() << std::endl;
Square s2{
s1 };
std::cout << "Squares: " << Square::getNumberOfObjects() << std::endl;
Square* s3 = new Square{
s1 };
std::cout << "Squares: " << Square::getNumberOfObjects() << std::endl;
std::cout << "s3's area is" << s3->getArea()<<std::endl;
delete s3;
std::cout << "Squares: " << Square::getNumberOfObjects() << std::endl;
return 0;
}
结果如上图所示。