What is the most efficient way to append one std::vector to the end of another?

Question

Let v1 be the target vector, v2 needs to be appended to the back of it.

I\'m now doing:

v1.reserve(v1.size() + v2.size()); 
copy(v2.begin(), v2.end()         


        

Answer 1

Probably better and simpler to use a dedicated method: vector.insert

v1.insert(v1.end(), v2.begin(), v2.end());

As Michael mentions, unless the iterators are input iterators, the vector will figure out the required size and copy appended data at one go with linear complexity.