Question

I’m writing a random access container in C++. In my code I use this (well, in my real code I use all kinds of Allocator typedefs, this is just easier to understand):

template<typename T, typename Allocator = std::allocator<T> >
class Carray {
public:
    // ...
    typedef T* iterator;
    typedef const T* const_iterator;
    // ...
};

But I can also create a different iterator class derived from std::iterator. This would add support for typedefs (it::iterator_category, it::difference_type, etc).

Now my question, is there an overhead by using a iterator class instead of a raw pointer? If yes, how substantial is this overhead, and is it severe enough to not use a iterator class?

Answer 1

You have iterator category, difference type etc avalaibale for you even if you have a raw pointer. You see, there is this iterator_traits<> template which you should use. It is already specialized for pointers.

iterator_traits<int*>::value_type // ... etc. 
//or
iterator traits<my_custom_iterator>::value_type