Question

I am not really sure what this line of code does.

 vector<vector<A>> someth;

Does this mean that creates a vector with elements vectors with objects of class A?
Can please someone explain this?

Thanks

Answer 1

Yes.

Also note that your syntax is not supported before C++11:

vector<vector<A> > someth;

is the pre-C++11 syntax. Before that, >> was treated as the bit-shift operator, so you’d get a compiler error on some compilers.

This actually creates an empty vector that can contain objects of type vector<A>.