------- Additional Comments From pcarlini at suse dot de 2005-09-07 16:28 ------- (In reply to comment #7) > The ANSI definition for %x (or %X) only covers unsigned integers. Surely then > doing hex formatting on a signed integer would at the very least be undefined > behavior.
Yes, you have a point that the mapping prescribed by the ISO/IEC Standards is not very precise, because, strictly speaking, the C Standard speaks only about unsigned int and the C++ Standard mandates "%x" for many different types (see 22.2.2.2.2/Stage1): then the user is allowed to invoke undefined behavior if he uses "hex" together with anything != unsigned int, that is, basically, *always* because unsigned int is not among the types over which do_put is overloaded! I consider this a defect of the C++ Standard and will take care of reporting it to the LWG Commitee. Thanks for pointing it out! As long as libstdc++-v3 is concerned, what we are doing in such circumstances, is implementing a kind of behavior, which is the one usually implemented by printf. This is good, in my opinion, because consistent with printf, thus very useful when C++ and C code interoperate. You are right that in principle libstdc++-v3 could well crash and remain conforming ;) -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23757
