STL iterator before std::map::begin()

Question

In C++11\'s std::map, is there some valid iterator x such that ++x is guaranteed to equal map::begin()? I would like to detect i

Answer 1

By "walk the iterator off the front" I presume you are decrementing a forward iterator something like this:

// don't do this:
for(it = mymap.end(); --it >= mymap.begin(); ) { ... }

Instead, increment a reverse iterator like this:

// this is better:
for(it = mymap.rbegin(); it != mymap.rend(); ++it) { ... }

-Jesse