#c++#代码分析QAQ

Question

写出下面代码的输出结果，并进行代码输出分析

#include<iostream>
using namespace std;
class BaseA
{
public:
    BaseA(int a, int b);
    ~BaseA();
protected:
    int m_a;
    int m_b;
};
BaseA::BaseA(int a, int b) :m_a(a), m_b(b) {
    cout << "BaseA constructor" << endl;
}
BaseA::~BaseA() {
    cout << "BaseA destructor" << endl;
}
class BaseB {
public:
    BaseB(int c, int d);
    ~BaseB();
protected:
    int m_c;
    int m_d;
};
BaseB::BaseB(int c, int d) :m_c(c), m_d(d) {
    cout << "BaseB constructor" << endl;
};
BaseB::~BaseB() {
    cout << "BaseB destructor" << endl;
}
class Derived :public BaseA, public BaseB {
public:
    Derived(int a, int b, int c, int d, int e);
    ~Derived();
public:
    void show();
private:
    int m_e;
};
Derived::Derived(int a, int b, int c, int d, int e) :BaseA(a, b), BaseB(c, d), m_e(e) {
    cout << "Derived constructor" << endl;
}
Derived::~Derived() {
    cout << "Derived destructor" << endl;
}
void Derived::show() {
    cout << m_a << "," << m_b << "," << m_c << "," << m_d << "," << m_e << endl;
}
int main() {
    Derived obj(1, 2, 3, 4, 5);
    obj.show()；
    return 0;
}

Answer 1

BaseA constructor
BaseB constructor
Derived constructor
1,2,3,4,5
Derived destructor
BaseB destructor
BaseA destructor

代码输出分析如下：

首先创建了一个 Derived 类型的对象 obj，在创建过程中调用了 Derived 的构造函数。
在 Derived 构造函数中，首先调用 BaseA 的构造函数，输出 "BaseA constructor"，然后调用 BaseB 的构造函数，输出 "BaseB constructor"，最后初始化 Derived 的成员变量 m_e。
在 Derived 构造函数执行完成后，调用 obj 的 show() 函数，输出 m_a、m_b、m_c、m_d 和 m_e 的值。
main 函数执行完成后，销毁了 obj 对象，调用了 Derived 的析构函数，输出 "Derived destructor"；接着调用 BaseB 的析构函数，输出 "BaseB destructor"；最后调用 BaseA 的析构函数，输出 "BaseA destructor"。