Neither auto nor typename in C++ provides the ability to get a variable's type and create new types using that information. To better explain why you might want to do this, let's look at the following example:
template<typename FUNC>auto question(FUNC &&func){ auto x = func() + 10; return x;}
We start our example with a function that takes any function as an input and returns the result of this function plus 10. We can then execute this function as follows:
short the_answer(){ return 32;}int main(void){ auto i = question(the_answer); show_type(i);}
As shown in the preceding example, we pass the question() function a pointer to another function that returns short. On executing this function, we store the results and then we ...
