Often when iterating through a string (or any enumerable object), we are not only interested in the current value, but also the position (index). To accomplish this by using
I would use it-str.begin() In this particular case std::distance and operator- are the same. But if container will change to something without random access, std::distance will increment first argument until it reach second, giving thus linear time and operator- will not compile. Personally I prefer the second behaviour - it's better to be notified when you algorithm from O(n) became O(n^2)...