C++进阶：新人易入的那些坑 --4.编译器生成的函数

最新推荐文章于 2024-06-09 20:38:12 发布

翻译最新推荐文章于 2024-06-09 20:38:12 发布 · 206 阅读

C++易入的坑专栏收录该内容

8 篇文章

订阅专栏

本文深入探讨了C++中编译器自动生成的四个默认成员函数：拷贝构造函数、拷贝赋值运算符、析构函数和默认构造函数。通过具体示例，解析了这些函数的工作原理和它们在不同情况下的行为。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

//########################################################################
/*
Compiler silently writes 4 functions if they are not explicitly declared
1.Copy constructor
2.Copy Assignment Operator
3.Destructor
4.Default constructor(only if there is no constructor declared).
*/

class dog {};
/* equivalent to */
class dog
{
public:
	dog(const dog& rhs)
	{
		...//Member by member initialization
	};
	dog& operator=(const dog& rhs)
	{
		//member by member copying
	};
	dog() {};
	//1.call base class's default constructor;
	//2.call data member's default constructor;
	~dog() {};
	//1.call base class's destructor;
	//2.call data member's destructor;
};
/*
1.They are public and inline.
2.They are generated only if they are needed.
*/

//Example:
class dog
{
public:
	string m_name;
	dog(string name = "Bob")
	{
		m_name = name;
		cout << "is born" << endl;
	}
	~dog()
	{
		cout << m_name << "is destroyed.\n" << endl;
	}
};

int main()
{
	dog dog1("Henry");
	dog dog2;
	dog2 = dog1;
}
/*
OUTPUT:
Henry is born.
Bob is born.
Henry is distroyed.
Henry is distroyed.
*/

/*example 2*/
class collar
{
public:
	collar()
	{
		std::cout << "collar is born.\n";
	}
};

class dog
{
	collar m_collar;
	//string& m_name;//this snippet will not be compiled
};

int main()
{
	dog dog1;
}

/*C++ 11 updata: */
class dog
{
public:
	dog() = default;
	dog(string name) { ... };
};