Best way to manage list of users?

I want to store information about users. When a new user is added my program needs to look thru each user record to see if that name is allready in use. Should I do this using classes? How do I search thru each class?
I thought of having the class like this

Code:

---

class User
{
  char Name[20];
  class *Next;
}

---

And then I would use the next pointer to look thru all classes but what would be the best way to fill in the next pointer?

Once you declare the class User, you need to declare instances of the User class (that is individual objects) to do anything useful. You can store the objects in any container you wish to simplify your task. Then search container by whatever mechanism is appropriate for the contaier. Containers include basic arrays and lists, containers from the Standard Template Libraray like vectors, queues, stacks, etc, non standard third party containers, and user declared/defined containers.

Classes default to private access. What you'd want is one of the following (equivalent) forms:

Code:

---

struct User
{
  char Name[20];
  User* Next;
}

... or ...

class User
{
public:
  char Name[20];
  User* Next;
}

---

I just noticed that I didn't answer your question.

The data structure that you have described is a singly-linked list. (There is a brief tutorial at http://www.cprogramming.com/tutorial/lesson15.html and Google would be an invaluable reference to get more information.)

This will work for your purposes. You could just put the new nodes at the end and then search through the entire list, looking for the item, and then adding it if it isn't there. (You could order your list using an insertion sort algorithm, but this will not be of much help.)

A slightly more complicated data structure that you could use is an ordered binary tree, and this would improve efficiency (worst case, it would be no worse than a linked list). Getting more advanced there are algorithms to balance binary trees as well.

Starting off, however, a linked list is good.

The search method that you would use with linked lists is sequential search. The algorithm you'd use for binary trees is called binary search.

If you are not trying to do an exercise in data structure programming (a good exercise, though), you may want to look into using the std::list class.