Question

I’m trying to extend this class

template <class T> class dynamic_array

This does not work

class merge_sort : public dynamic_array

What is the proper way to extend the class?

Answer 1

You have to provide an argument for the template. If you want to use a fixed argument, say int, then you would do:

class merge_sort : public dynamic_array< int >

If you instead want to keep the extended class as generic, you would do:

template< class T >
class merge_sort : public dynamic_array< T >

Note that merge sort is an algorithm, and as such it would be better off as a free function than as an object. According to OOP, you should ask is merge_sort a dynamic_array? For me the answer sounds as no, so I would do this instead:

template< class T >
void merge_sort( dynamic_array< T >& array ){ ... }