Question

I want to sort a vector using sort algorithm in C++.

str is the name of std::vector<int> I want to sort.

What’s the difference between this:

std::sort(str.rend(),str.rbegin())

and this:

std::sort(str.begin(),str.end())

Answer 1

Assuming you intend to use std::sort to sort the string (since neither std::vector nor std::string have a sort method), the first statement is incorrect and leads to undefined behaviour (UB):

std::sort(str.rend(),str.rbegin());

Here, std::sort will attempt to dereference str.rend(), which is a “past the end” iterator. De-referencing such an iterator is UB.

A correct use of reverse iterators would be

std::sort(str.rbegin(),str.rend());

This would result in the string/vector being sorted in descending order.