Question

So from what I understand, reserve doesn’t initialize the the abstractions but simply allocates space in order to contain them. However shouldn’t v[0] always give you the first unitialized memory and shouldn’t assigning a value into it always work?

Answer 1

Because reserve does not change the size of the vector. It only moves the vector to a place in memory where there is enough space to allow the size of the vector to increase when it becomes necessary.

If you want to be sure you can call v[0]=2, or even v[1]=0, you should use resize(2), not reserve(2).