How to differate two default constructors or some other solution.

[Townsheriff]

I have class student

Student{
public:
   Student(){
      id = idCounter++;
   }
private:
    static int idCounter;
    int id;
}

but when I want to do:

Student *list = new Student[10];

and then:

list[0] = Student(); // this students id will be 10 or 11 

I wrote this for you to see. Those classes I have are very long that why I didnt add them here.

So how can I avoid this? One way would be make different constructors, but that seems to be bad idea.

[Peter87]

When you create the array it will automatically create all Student objects in it using the default constructor, so no need to do things like list[0] = Student();.

[Townsheriff]

Yes but my counter skyrockets. How can I avoid it?

[Townsheriff]

Im creating two classes one is something like vector and second is student. And I need to my vectorish object hold student objects.

[Peter87]

Well, you could create less objects...

Do you understand what list[0] = Student(); is doing? First a temporary object of type Student is created using the default constructor. The temporary object is then assigned to the already existing object list[0]. This means that list[0].id will be set to the id of the temporary object. And then, before the statement ends, the temporary object is destroyed. What happens is similar to this:

{
	Student tmp;
	list[0] = tmp;
}

So, can't you just avoid doing this?

If that is not an option, well maybe you should move the id generation to a function instead so that you can do: list[0].giveUniqueId();

[Townsheriff]

I understand what you are saying, but then how I should be making my list(vectorish) class?
Now it is :

template <class T> 
List{
private:
    T* _list;
public:
    List(){
       _list = new T[10];
    }
}

basically its like this, but size can change. When I add new values and _list is full then it creates new pointer with holds more T types.

[Peter87]

You could use placement new. Learn about it if you are interested. Not really a beginner subject though.