Question

how can i create a clss in gdbonline

Answer 1

As far as I know, onlinegb is just a bit of "wiring" around g++ and gdb. Any proper C11 construct should work here as it works in g++.

Answer 2

Just as you do in any C++ program:

class Name

{

string firstname;

string lastname;

public:

  void print()

 {

   cout << firstname << " " << lastname << endl;

}

};

Answer 3

See https://onlinegdb.com/S1v6LUtEH