does boost regex support 64-bit for SunOS 5.8, HP-UX 11i (native compilers), WIN (MSVC-6) ? we are using an old(?) version - regexpp version 3.12. Is it recommended to upgrade to the latest version ? Is it essential to upgrade to the latest version with relevance to 64-bit compilation ?

64-bit support should be fine in most recent versions (there was a 64-bit related bug in one release, but I forget which one now, it was some time ago now). However the compilers you mention are particularly broken when it come to compiling any kind of vaguely advanced C++ : The sun compiler should just about handle regex, as will MSVC 6, but HP aCC is just so broken we've never been able to port even the most basic Boost libraries to it, sorry... but see also http://lists.boost.org/MailArchives/boost/msg63570.php John.