Question

I understand the concept but i don’t know why i require to use non-type template arguments ?

Answer 1

There are many use-cases, so let’s look at a couple of situations where they are indispensable:

• Fixed sized array or matrix classes, see for example C++11 std::array or boost::array.

• A possible implementation of std::begin for arrays, or any code that needs the size of a fixed size C style array, for example:

return the size of an array:

template <typename T, unsigned int N>
unsigned int size(T const (&)[N])
{
  return N;
}

They are also extremely useful in template metaprogramming.