Question

in C++, I have two list<T> objects A and B and I want to add all the members of B to the end of A. I’ve searched a few different sources and haven’t found a simple solution (e.i. A.append(B);) and this surprises me a bit.

What is the best way to do this?

As it happens, I don’t care about B after this (it gets deleted in the very next line) so if there is a way to leverage that for better perf I’m also interested in that.

Answer 1

If you want to append copies of items in B, you can do:

a.insert(a.end(), b.begin(), b.end());

If you want to move items of B to the end of A (emptying B at the same time), you can do:

a.splice(a.end(), b);

In your situation splicing would be better, since it just involves adjusting a couple of pointers in the linked lists.