begin() vs rbegin() 它们是如何实现的？

Question

In the following image I'm using the same type of iterators which means the same implementation of operator++ so how does the compiler know if it should get the next value or the previous one...?

Answer 1

First, the picture you have contains an error. As you can see here the reverse iterator type of vector is std::reverse_iterator<iterator> which uses the template std::reverse_iterator<T> . So begin and rbegin have not the same return value (and I also do not think they are convertible to each other).

But actually that wouldn't even be a problem, you could implement

struct iter {
    bool reverse;
    pointer ptr;
 
    iter& operator++() {
        if(reverse) --ptr;
        else ++ptr;
        return *this;
     }
};

But type-seperating them is really preferable.