c++ 初始化列表构造函数初始化父类变量

c++ 初始化列表构造函数初始化父类变量，可以在构造时主动调用父类的含参构造函数

#include<iostream>
using namespace std;

class Person
{
public:
    string _name;
    string getNickName();
    Person(string name):_name(name){};
private:
    void initNickName();
    string _nickName;
};

string Person::getNickName()
{
  initNickName();
  return _nickName;
}

void Person::initNickName()
{
  _nickName="hahaha"+_name;
}

class Student: public Person
{
public:
  Student(string name, int id):Person(name), _id(id){};
  // Student(string name, int id):_name(name), _id(id){}; // 这样写会报错
  int getId();
private:
  int _id;
};

int Student::getId()
{
  return _id;
}

int main (int argc, char *argv[]) {
  cout<<"hello"<<endl;
  Student stu("xiaoming", 10);
  cout<<stu.getNickName()<<endl;
  cout<<stu.getId()<<endl;
  return 0;
}