了解嵌套结构

Question

I'm currently working on a program that requires a nested structure. Though, I am not sure I understand it. I'd like your help with this if anyone could. First week learning C++ so don't give me a hard time :P

I'm supposed create a Person structure containing two string members, first and last. Create an Address structure containing four string members, street, city, state, and zipcode. And also create a nested structure, Employee, that consists of three members. A Person member named name, an Address member named homeAddress and an int member named eid.

I think I've done most of it correctly, but I am getting an incomplete type is not allowed under my Address homeAddress for some reason. Also, when it says create a nested structure "Employee" does that mean I have to declare Employee somewhere?

Here is what I have so far, thanks in advance.

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

struct Person {
    string first;
    string last;
};

struct Address {
    string street;
    string city;
    string state;
    string zipcode;

    Person name;
    Address homeAddress;
    int eid;
};

Answer 1

Your code was almost complete. It should be:

struct Person {
  string first;
  string last;
};

struct Address {
  string street;
  string city;
  string state;
  string zipcode;
};

struct Employee {
  Person name;
  Address homeAddress;
  int eid;
};

Now the misnomer here is that nested can also imply visibility or scope. Hence, if you wanted to define the structure Address and Person within Employee , it would look like this:

struct Employee {
  struct Address {
    //..
  };
  struct Employee {
    //..
  };
  Person name;
  Address homeAddress;
  int eid;
};

That way, you make the scope of Person and Address native to that of Employee alone.

Answer 2

You are very close

struct Person {
    string first;
    string last;
};

struct Address {
    string street;
    string city;
    string state;
    string zipcode;
};

struct Employee {
    Person name;           // instance of Person struct from above
    Address homeAddress;   // instance of Address struct from above
    int eid;
};

Note that this last struct is "nested" as you describe it, since it is a struct that contains members that are two other types of struct .