Hi, I think this is a bug but I'm willing to believe I'm misusing something. As a side point, I'm unsure of how to choose the regex syntax. I think I use boost::regex::perl as the second argument to the constructor but I haven't had much look with either that or the char_classes value. Anyway for me the snippet below the ----s hangs in the second find_all_regex. Ok, it may not hang, it may be building up a nice big core to dump but I only leave it for 20 seconds or so. This started with me trying to use find_regex which segfaulted when I tried to increment the iterator for the first time. I thought that might be me so I tried the safer way of just asking someone else to do all the real work :). This might prompt calls of "known issue." if I haven't messed up. In which case would someone care to hit me with a clue stick as to how I should check before bugging the list? Thanks for your time. Using Debian unstable: ii libboost-regex 1.32.0-2 regular expression library for C++ ii libboost-regex 1.32.0-2 regular expression library for C++ which I'm pretty sure is one for the library and one for the dev headers but I'm a noob there too, so I could be wrong. The compiler is: $ g++ -v Reading specs from /usr/lib/gcc-lib/i486-linux/3.3.5/specs Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/c++/3.3 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --enable-__cxa_atexit --enable-clocale=gnu --enable-debug --enable-java-gc=boehm --enable-java-awt=xlib --enable-objc-gc i486-linux Thread model: posix gcc version 3.3.5 (Debian 1:3.3.5-8) -------------- #include <string> #include <iostream> #include <boost/algorithm/string_regex.hpp> template<class T> std::ostream& operator<<(std::ostream& cout, const std::vector<T>& v) { std::copy(v.begin(), v.end(), std::ostream_iterator<T>(cout, " ")); return cout; } main() { std::string line1("word -opt 5 -opt 45M -flag word -flag -opt word"); typedef boost::find_iterator<std::string::iterator> fi; for (fi i = boost::make_find_iterator(line1, boost::first_finder("word", boost::is_equal())); ! i.eof(); ++i) { std::cout << boost::copy_iterator_range<std::string>(*i) << std::endl; } std::vector<std::string> result; boost::regex rx1(" [-a-z]*"); boost::find_all_regex(result, line1, rx1); std::cout << result.size() << result << std::endl; result.clear(); boost::regex rx2("[-a-z]*"); boost::find_all_regex(result, line1, rx2); std::cout << result.size() << result << std::endl; std::cout << line1 << std::endl; } -- Blue Skies