On Tue, Jan 29, 2013 at 10:56 AM, Rob Stewart <robertstewart@comcast.net>wrote:
On Jan 28, 2013, at 5:12 PM, Joel de Guzman <djowel@gmail.com> wrote:
On 1/29/13 5:58 AM, Gottlob Frege wrote:
How do I know if is it singular valued?
>
How do you know if an iterator is singular valued? You can't. Same here.
it == container.end()?
Or am I confused?
Nope. A singular valued iterator may not be compared. A singular valued iterator is not associated with any sequence. E.g default constructed iterator pointing to nowhere.
Singular iterators are default constructed instances that represent a universal end iterator.
This is only true for some iterators. Generally, comparing to default constructed iterators is UB; for example comparing to default initialized pointers. It is generally not possible to discover a singular iterator. HTH, -- gpd