c++构造和析构顺序

文章目录

c++构造和析构顺序

结论

  • 构造顺序:
    • 按照继承顺序调用基类的构造函数。
    • 按照声明顺序调用成员变量的构造函数。
    • 调用派生类的构造函数(体)。
  • 析构顺序(与构造顺序完全相反):
    • 调用派生类的析构函数(体)。
    • 按照声明顺序的反序调用成员变量的析构函数。
    • 按照继承顺序的反序调用基类的析构函数。

例子

cpp 复制代码
#include <iostream>

using namespace std;

class Base1 {
public:
    Base1() {
        cout << "Base1()" << endl;
    }

    virtual ~Base1() {
        cout << "~Base1()" << endl;
    }
};

class Base2 {
public:
    Base2() {
        cout << "Base2()" << endl;
    }

    virtual ~Base2() {
        cout << "~Base2()" << endl;
    }
};

class Member1 {
public:
    Member1() {
        cout << "Member1()" << endl;
    }

    ~Member1() {
        cout << "~Member1()" << endl;
    }
};

class Member2 {
public:
    Member2() {
        cout << "Member2()" << endl;
    }

    ~Member2() {
        cout << "~Member2()" << endl;
    }
};

class Member3 {
public:
    Member3() {
        cout << "Member3()" << endl;
    }

    ~Member3() {
        cout << "~Member3()" << endl;
    }
};

class Dervied : public Base1, public Base2 {
public:
    Dervied() : m3(), m1() {
        cout << "Dervied()" << endl;
    }
    ~Dervied() {
        cout << "~Dervied()" << endl;
    }

private:
    Member1 m1;
    Member2 m2;
    Member3 m3;
};

class Dervied2 : public Base2, public Base1 {
public:
    Dervied2() : m2(), m3(), m1() {
        cout << "Dervied()" << endl;
    }
    ~Dervied2() {
        cout << "~Dervied()" << endl;
    }

private:
    Member1 m1;
    Member2 m2;
    Member3 m3;
};

int main() {
    Base1 *b = new Dervied();
    cout << "---------------------" << endl;
    delete b;
    cout << "---------------------" << endl;
    Base1 *b1 = new Dervied2();
    cout << "---------------------" << endl;
    delete b1;
    return 0;
}

输出:

复制代码
Base1()
Base2()
Member1()
Member2()
Member3()
Dervied()
---------------------
~Dervied()
~Member3()
~Member2()
~Member1()
~Base2()
~Base1()
---------------------
Base2()
Base1()
Member1()
Member2()
Member3()
Dervied()
---------------------
~Dervied()
~Member3()
~Member2()
~Member1()
~Base1()
~Base2()
相关推荐
感哥12 小时前
C++ 面向对象
c++
沐怡旸13 小时前
【底层机制】std::shared_ptr解决的痛点?是什么?如何实现?如何正确用?
c++·面试
感哥20 小时前
C++ STL 常用算法
c++
saltymilk1 天前
C++ 模板参数推导问题小记(模板类的模板构造函数)
c++·模板元编程
感哥1 天前
C++ lambda 匿名函数
c++
沐怡旸2 天前
【底层机制】std::unique_ptr 解决的痛点?是什么?如何实现?怎么正确使用?
c++·面试
感哥2 天前
C++ 内存管理
c++
博笙困了2 天前
AcWing学习——双指针算法
c++·算法
感哥2 天前
C++ 指针和引用
c++
感哥2 天前
C++ 多态
c++