You'll want to read these changelogs for the CRT and the STL: http://blogs.msdn.com/b/vcblog/archive/2014/06/18/crt-featur... , http://blogs.msdn.com/b/vcblog/archive/2014/06/06/c-14-stl-f... , and http://blogs.msdn.com/b/vcblog/archive/2015/07/14/stl-fixes-... .