```#include #include class Address; //forward declaration class Employee { private: std::string name; int age; Address& address; public: Employee(std::string n, int a, Address& add) : name(n), age(a), address(add) {},; void displayEmp() { std::cout << "Employee: " << name << " Age: " << age << std::endl; address.displayAdd(); },; },; class Address { private: std::string address; public: Address(std::string a) { address = a; },; void displayAdd() { std::cout << "Address: " << address << std::endl; },; },; int main() { Address add1("601 Cloverfield"); Employee emp1("Bob", 35, add1); emp1.displayEmp(); },``` - line 15 use of undefined type 'Address'?
Can't access `Address` before it's defined. `class Address;` is only good enough to make references and pointers, `address.displayAdd();` doesn't exist here.