C++构造和析构调用顺序

构造函数执行顺序

1.基类构造函数（如有多个则按基类声明顺序从左到右）

2.成员变量构造函数（如果有多个按成员变量声明顺序）

3.执行自身构造函数

析构函数执行顺序（与构造相反）

1.自身析构

2.成员析构（与声明顺序相反）

3.基类析构（从右自左）

#include <iostream>
using namespace std;
class B
{
public:
    int m_b;
public:
    B()
    {
        cout << "B构造" << endl;
    }
    B(int b)
    {
        m_b = b;
        cout << "B有参构造" << endl;
    }
    ~B()
    {
        cout << "B析构" << endl;
    }
};

class A
{
public:
    int m_a;
    B objB;
public:
    A()
    {
        cout << "A构造" << endl;
    }
    A(int a, int b) : objB(b), m_a(a)
    {
        cout << "A有参构造" << endl;
    }
    ~A()
    {
        cout << "A析构" << endl;
    }
};

class C
{
public:
    int m_c;
public:
    C()
    {
        cout << "C无参构造" << endl;
    }
    C(int c) : m_c(c)
    {
        cout << "C有参构造" << endl;
    }
    ~C()
    {
        cout << "C析构" << endl;
    }
};

class D
{
public:
    int m_d;
public:
    D()
    {
        cout << "D无参构造" << endl;
    }
    D(int d) : m_d(d)
    {
        cout << "D有参构造" << endl;
    }
    ~D()
    {
        cout << "D析构" << endl;
    }
};

class E : public A, public C
{
public:
    int m_e;
    D objD;
public:
    E()
    {
        cout << "E无参构造" << endl;
    }
    E(int a, int b, int c, int d) : A(a, b), C(c), objD(d)
    {
        cout << "E有参构造" << endl;
    }
    ~E()
    {
        cout << "E析构" << endl;
    }
};

int main(int argc, char *argv[])
{
    E objE(10, 20, 30, 40);
    return 0;
}

输出如下

B有参构造
A有参构造
C有参构造
D有参构造
E有参构造
E析构
D析构
C析构
A析构
B析构