Constructor of a derived class with sub-objects

This is what I just saw today. I felt that I didn't know much about this part of content before, so I want to share it with you. First, we need to introduce the concept of object at once. Data members of a class can be basic types such as int and char, or class objects. For example, they can contain such data members: [cpp] Student s1; // Student is a declared class. In this case, s1 is an embedded object in the class object, that is, a sub-object, which is similar to a struct variable. Let's review the syntax of the simple derived class constructor: [cpp] class student {public: student (int n, string nam, char s) {num = n; name = nam; sex = s ;}~ Student () {} protected: int num; string name; char sex;}; class student1: public student {public: student1 (int n, string nam, char s, int, string ad): student (n, nam, s) {age = a; addr = ad ;}~ Student1 () {} private: int age; string addr;}; the general format of the derived class constructor is the name of the derived class (total parameter list): Base Class Name (parameter list) {new data member initialization statement for the derived class;} How to Write the derived class constructor of the sub-object? We all know that the object should be initialized at the time of creation, but obviously the initialization of the sub-object cannot be performed when the derived class is declared, because the class is an abstract type and is only a model, no specific data. Therefore, the initialization of sub-objects is implemented by calling the constructor of the derived class when a derived class is created. Add a shift leader in the example just now. The type of the shift leader is obviously student, so it is a subobject. The constructor is as follows: [cpp] student1 (int n, string nam, char s, int n1, string nam1, char s1, int a, string ad): student (n, nam, s), monitor (n1, nam1, s1) {age = a; addr = ad;} There are eight parameters in the constructor above. The first three are parameters of the base class constructor, parameters 4th, 5, and 6 are the sub-object constructor parameters, and the last two are used for data member initialization of the derived class. To sum up, the constructor format is as follows: name of the derived class Constructor (total parameter list): name of the base class Constructor (parameter list) and sub-Object Name (parameter list) {new data member initialization statement in the derived class}