Templated Class Declaration for KDTree

Question

The following class returns the following error from g++:

tree.h:9: error: expected unqualified-id before 'template'

If line 5 is uncommented, the same error occurs, only at line 5.

Am I missing an obvious syntax error here from staring at this too long? Or am I improperly declaring the template class?

#ifndef TREE_H
#define TREE_H


//template <typename T, typename P, typename C> class kdtree_t;

//Kdtree class

template <typename T, typename P, typename C> 
class kdtree_t{
private:
    struct node_t
    {
        P  data;
        T  min, max;
        node_t *left, *right;
        int axis;

        node_t(const P& d = 0, const T& in = 0, 
               const T& ix = 0, node_t *l = NULL, 
               node_t * r = NULL, int a = 0)
         : data(d), min(in), max(ix), 
           left(l), right(r), axis(a) {}
    };
public:
    void nn(T& q,  P& t, double radius)
    {
        nn(root, q, t, radius);
    } 

    void insert(std::vector<P>& x, const T& min, const T& max)
    {
        root = insert(root, x, min, max, 0);
    } 

    void knn(T& q, std::vector<P> vec, double r, int k)
    {
        knn(root, q, vec, r, k);
    } 

    void range(T& min, T& max, std::vector<P> irange)
    {
        this->range(root, min, max, irange);
    }

    void clear()
    {
        clear(root);
    }

private:

    void            nn(node_t* &,T&,P&,double&);
    void            knn(node_t* &,T&,std::vector<P>&,double&,int);
    void            range(node_t* &,const T&,const T&,std::vector<P>&);

    void            clear(node_t* &);
    node_t*         clone(node_t* ) const;

    node_t* root;
    node_t* insert(node_t * &, std::vector<P>&, const T&, const T&, int);

};

#endif

Answer 1

You're template code is correct, but the code that comes before it (likely in another header) is not. Check to make sure your class definitions in other headers have semi-colons after them.

class x // no semi-colon here causes same error!

template <typename T, typename P, typename C>
};

int main() {
}