How to manage one to many relationship between objects? ( move related ) - c++

Question

First of all I wanna say that I am very new to CPP (I started with cpp11) :)
Considering the following entities: Student(first name + last name) and Group (description + more students).
I created the following 2 classes in C++:
class Student
{
private:
std::string firstName;
std::string lastName;
Student(const Student &student);
Student& operator=(const Student &student);
public:
Student():firstName(""), lastName("") { }
Student(std::string firstName, std::string lastName):firstName(firstName), lastName(lastName) { }
Student(const Student &&student):firstName(student.firstName), lastName(student.lastName) { }
Student& operator=(const Student &&student) { this->firstName=student.firstName; this->lastName=student.lastName; return *this; }
std::string GetFirstName() const { return this->firstName; }
std::string GetLastName() const { return this->lastName; }
};
class Group
{
private:
std::string description;
std::vector<std::shared_ptr<Student>> students;
Group(const Group &group);
Group& operator=(const Group &group);
public:
explicit Group():description(""), students(std::vector<std::shared_ptr<Student>>()) { }
explicit Group(std::string description) :description(description), students(std::vector<std::shared_ptr<Student>>()) { }
void NewStudent(Student &&student) { students.push_back(std::make_shared<Student>(std::move(student))); }
std::vector<std::shared_ptr<Student>> GetStudents() const { return students; }
};
In main I have this:
Student s1("fn1","ln1");
Student s2("fn2","ln2");
//Student s3("fn3","ln3");
Group cppGroup("C plus plus");
cppGroup.NewStudent(std::move(s1));
cppGroup.NewStudent(std::move(s2));
cppGroup.NewStudent(Student("fn3", "ln3"));
//cppGroup.NewStudent(s3);
std::vector<std::shared_ptr<Student>> cppStudents=cppGroup.GetStudents();
My question is related to NewStudent method.
In the first 2 cases the parameter is move(s) and in the third case is Student(...).
My guess is that Student("fn3", "ln3") is the same as Student s3("fn3, "ln3") but if i pass s3 to the function it just won't compile with the following error: cannot convert from Student to Student&&
PS: I would appreciate if you helped me understand how to make the example I considered ideal.
Thank you very much.
LE: I think I understand what is happening, Visual Studio shows the following error: cannot convert an lvalue to a rvalue so my guess is that if I pass to NewStudent s3 it doesn't know how to convert it to a rvalue but if i pass it Student("fn3", "ln3") if will call the move constructor.

Answer 1

If that is really your design, you can simplify it a lot and do away with all the smart pointers and custom structors:
class Student
{
private:
std::string firstName;
std::string lastName;
public:
Student(std::string firstName, std::string lastName):firstName(firstName), lastName(lastName) { }
std::string GetFirstName() const { return this->firstName; }
std::string GetLastName() const { return this->lastName; }
};
class Group
{
private:
std::string description;
std::vector<Student> students;
public:
explicit Group(std::string description) :description(description) { }
void NewStudent(Student student) { students.push_back(student); }
std::vector<Student> GetStudents() const { return students; }
};

Answer 2

Student("fn3", "ln3") is a temporary object which does not posses a name. The compiler decides it can give it away because you have no chance of using it again. In the case of Student s2("fn2","ln2")
you are keeping a reference to the object in the variable s2. So you must explicitly give it away with the move statement.

Answer 3

I suggest changing your design and using smart pointers.
Have one container for all of the students.
A Group of students would have one or more smart pointers to students in the "all students" container.
This design allows you to have different themed groups without copying the student objects. The Group contain would contain copies of the smart pointers.
Using this design, you can also create indexes to order your students by differing criteria. For example, you could have an index of students sorted by first name and another index of students sorted by last name.