I'm wondering what the benefits of using rbegin() rather than end() - 1 are for STL containers.
For example, why would you use something like:
vector<int> v;
v.push_back(999);
vector<int>::reverse_iterator r = v.rbegin();
vector<int>::iterator i = r.base();
Rather than:
vector<int> v;
v.push_back(999);
auto r = v.end() - 1;
rbegin()
return an iterator with a reverse operator++
; that is, with a reverse_iterator
you can iterate through a container going backward.
Example:
#include <vector>
#include <iostream>
int main()
{
std::vector<int> v{0,1,2,3,4};
for( auto i = v.rbegin(); i != v.rend(); ++i )
std::cout << *i << '\n';
}
Furthermore, some standard containers like std::forward_list
, return forward iterators, so you wouldn't be able to do l.end()-1
.
Finally, if you have to pass your iterator to some algorithm like std::for_each
that presuppose the use of the operator++
, you are forced to use a reverse_iterator
.