“error: Expected a type, got 'classname'” in C++

Question

Using the following code:

template 
class node {
    [. . .]
};
class b_graph {
friend istream& operator>> (istream& in, b_graph&         


        

Answer 1

node is not a class, it's a class template. You need to instantiate it to use it as the element type of vector, e.g.,

vector<node<int> > vertices;

(int is used as an example; you should use the type you actually need)