what about changing your code to the following? any noticeable speed changes?

size_t size = data.size(); for (size_t i = 1; i != size; ++i) { data[i] += data[i - 1] ; }

FB recently introduced Enhanced Auth Dialog which solves the problem you mention about.(https://developers.facebook.com/docs/opengraph/authenticatio...)

It allows users to remove permissions such as posting to facebook.

Unfortunately it is opt-in for apps.