Template Class in C++ - trouble writing begin for linked list

This is your problem:

return iterator itr( head->next );

You should probably be doing this:

return iterator( head->next );

The code as you have it is trying to declare an iterator named itr, which is a statement, not an expression (as required by return).

I'm not using the same compiler as you, but; I included the header in the cpp rather than the other way around, added a 'using' for your namespace in the cpp, and fixed the function signature of the implementation of operator= and that got what you've given us to build.