Remove first N elements from a std::vector

Question

I can\'t seem to think of a reliable way (that also compacts memory) to remove the first N elements from a std::vector. How would one go about doing that?

Answer 1

Use the .erase() method:

// Remove the first N elements, and shift everything else down by N indices
myvec.erase(myvec.begin(), myvec.begin() + N);

This will require copying all of the elements from indices N+1 through the end. If you have a large vector and will be doing this frequently, then use a std::deque instead, which has a more efficient implementation of removing elements from the front.