Why std::set provides begin() and end() if we can not modify the set elements

Question

As the elements of the std::set are in sorted order and each element is unique. Also we can't modify the elements of the set, then why the library provides the begin() and end() functions as we already have cbegin() and cend().

Answer 1

Because if you removed these functions, you would not be able to use std::set in many places where a Container is expected. The most obvious one (to me)¹:

for (auto x: mySet) { }

Would not be possible because the range-based for loop rely on begin and end, not cbegin or cend (§6.5.4/1.3).

One other example where this would pose a problem would be the std::begin² function, which, as you can see in the link, rely on c.begin() and not c.end().

The basic idea is that you do not want std::set to have a different interface than the other standard containers.

¹ There are many places like that, this is just one example among others.

² Note that even std::cbegin rely on the const-overload of c.begin() rather than on c.cbegin().