No display from glDrawElements

Question

When I use glDrawArrays I get a triangle in the middle of my screen, as expected. But when I try to use glDrawElements nothing comes up at all.

I have tried all sorts of

Answer 1

I think this:

unsigned int index[] = {
    1, 2, 3,
};

should be this:

unsigned int index[] = {
    0, 1, 2,
};