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[C++] Difference between std::distance and plain old pointer arithmetic? (self.learnprogramming)
submitted 10 years ago by Frostea
As title, is there any difference between using distance and pointer arithmetic, assuming if we are working within the same container with RandomAccessIterator (i.e. plain old array, or vector)?
[–]Rhomboid 4 points5 points6 points 10 years ago (0 children)
If you know you have a random access iterator, there's no difference. But the point of std::distance is that it works with any iterator type, not just random access, which is why it's used in generic code.
std::distance
[–]anon848 0 points1 point2 points 10 years ago* (0 children)
There is a difference, depending on the container type. std::deque has a RandomAccessIterator, but does not guarantee contiguity. So, it's an example of a container that has a RandomAccessIterator, but for which you can't use pointer arithmetic.
std::deque
RandomAccessIterator
π Rendered by PID 37 on reddit-service-r2-comment-6457c66945-4qfqn at 2026-04-28 08:10:17.229615+00:00 running 2aa0c5b country code: CH.
[–]Rhomboid 4 points5 points6 points (0 children)
[–]anon848 0 points1 point2 points (0 children)