C++学习日志22--对象的拷贝、匿名对象的使用

---

一、对象的拷贝

#include<iostream>

class Square 
{
    
    
private:
	double side = 1.0;
public:
	Square() = default;
	Square(double side)
	{
    
    
		this->side = side;
	
	}
	double getArea()
	{
    
    
		return (side * side);
	}

};
int main()
{
    
    
	Square s1, s2{
    
     4.0 };
	std::cout << s1.getArea() << std::endl;
	std::cout << s2.getArea() << std::endl;

	s1 = s2;

	std::cout << s1.getArea() << std::endl;
	std::cout << s2.getArea() << std::endl;


}

得到结果如上图所示。

二、匿名对象的使用

#include<iostream>
using std::cout;
using std::endl;

class Account 
{
    
    
private: 
	double balance;
public:
	Account()
	{
    
    
		balance = 0.0;
	}
	Account(double balance_)
	{
    
    
		balance = balance_;
	}
	void deposit(double amount)
	{
    
    
		balance += amount;
	}
	double withdraw(double amount)
	{
    
    
		auto temp{
    
     0.0};
		if (balance < amount)
		{
    
    
			temp = balance;
			balance = 0;
			return(temp);
		}
		else
		{
    
    
			balance -= amount;
			return(amount);
		}
	}
};

int main()
{
    
    
	Account a1;
	Account a2 = Account(100.0);

	a1.deposit(9.0);

	cout << a1.withdraw(10) << endl;
	cout << a2.withdraw(52.00) << endl;
	cout << Account(1000.0).withdraw(1001.0) << endl;

	return (0);



}

匿名对象调用时存在，调用结束后消失。