"used without template parameters"

Question

I realize similar questions have been asked before, but I read a couple of those and still don't see where I'm going wrong. When I simply write my class without separating the prototype from the definition, everything works fine. The problem happens when I separate the prototype and definition as shown below:

template<class T> class VisitedSet {  public:     VisitedSet();      int getSize();      void addSolution(const T& soln);      void evaluate();  private:     vector<T> vec;     int iteration; }; 

And as an example of a definition that gives me this error:

int VisitedSet::getSize() {     return vec.size(); 

I've never made a templated class before, so please pardon me if the problem here is trivial.

Answer 1

VisitedSet is a template, not a class, so you can’t use VisitedSet in a nested name specifier such as VisitedSet::getSize(). Just as you specified the declaration of class VisitedSet<T> for all class T, you must specify the definition of VisitedSet<T>::getSize() for all class T:

template<class T> int VisitedSet<T>::getSize() { //            ^^^     return vec.size(); } 

The name of a template can, however, be used as though it were a class within a template definition:

template<class T> struct Example {     Example* parent;     T x, y; }; 

In this case, Example is short for Example<T>.

Answer 2

You want this:

template <class T> int VisitedSet<T>::getSize() {     return vec.size(); }