You need to use your ISP's news server or Deja News for these:
comp.lang.c++.moderated - moderated C++ discussion group. (via Deja News.)
comp.std.c++ - discussion of the Draft C++ Standard. (via Deja News.)
comp.lang.c++ - a very busy group (unfortunately with many off-topic messages <sigh>). (via Deja News.)
comp.std.c - C standardisation discussion (via Deja News.)
comp.lang.c - a very busy C discussion group. (via Deja News.)