子类继承父类后，当创建子类对象，也会调用父类的构造函数

问题：父类和子类的构造和析构顺序是谁先谁后？

• 如果是单继承 ```cpp

  include

  using namespace std; class Person{ public: Person(){

    cout << "Person构造函数的调用" << endl;

  } ~Person(){

    cout << "Person析构函数的调用" << endl;

  } };

class Student:public Person{ public: Student(){ cout << “Student构造函数的调用” << endl; } ~Student(){ cout << “Student析构函数的调用” << endl; } }; int main(){ Student student; return 0; }

![image.png](https://cdn.nlark.com/yuque/0/2021/png/21436600/1623930072953-274dbc5e-6606-46ae-a604-a37ec88469e0.png#align=left&display=inline&height=406&originHeight=541&originWidth=998&size=142244&status=done&style=none&width=749)
会先调用父类的构造函数，然后再调用子类的构造函数<br />**没有父亲，哪里来的儿子**<br />**<br />**<br />**
- **如果是多继承**
```cpp
#include <iostream>
using namespace std;
class Person{
public:
    Person(){
        cout << "Person构造函数的调用" << endl;
    } 
    ~Person(){
        cout << "Person析构函数的调用" << endl;
    }
};
class Worker{
public:
    Worker(){
        cout << "Worker构造函数的调用" << endl;
    }
    ~Worker(){
        cout << "Worker析构函数的调用" << endl;
    }
};
class Student:public Worker,public Person{
public:
    Student(){
        cout << "Student构造函数的调用" << endl;
    } 
    ~Student(){
        cout << "Student析构函数的调用" << endl;
    }
};
int main(){
    Student student;
    return 0;
}

单继承会依据继承顺序，来调用父类的构造函数，比如这里会依次调用Worker, Person和 Student的构造函数