Cannot understand the error msg: 'nonstatic member reference must be relative to specific object' [closed]

Answer 1

The error message clearly states that you are trying to access an object's member without an object: You need to distinguish classes and objects. A class defines how objects of that particular class look like, i.e., what data members and function members the objects support. You probably want to do something along the lines of

Employee worker;
worker.Info.ID = "ID";
std::cout << worker.Info.ID << '\n';

(assuming Info happens to be a data member of Employee whose type in turn has an ID data member.

Answer 2

Since you didn't supply any code, I am going to write my own. Your classes should look something like this.

class ID {
     public:
         string name;
         string ID;
};

class Employee : ID {};

int main(int argc, char **argv) {
     cin >> Employee.Info.ID;
}

There are alot of things wrong with the line:

cin >> Employee.Info.ID;

First of all Employee extends Info. It is not a member of Info. This means that all the members of Info become members of Employee. So the code would change to:

cin >> Employee.ID;

But there is still something wrong with this code. ID is an instance variable. Employee is not an instance it is a class. I am not entire sure what you want to do but there are two ways to fix this: 1) make ID a static variable or 2) create an instance of Employee.

1)

class ID {
     public:
         string name;
         static string ID; // Change to static
};

2)

 int main(int argc, char **argv) {
     Employee my_employee; // Create instance
     cin >> my_employee.ID;

What 1) does is set the ID's of all employers to the first word in cin. What 2) does is set the ID of my_employee (the instance we created) only.