Hi! I am trying to match a function body and find out if the params or return type have specific class name patterns. Therefore I did a really huge regex... sorry if is not so readable, but I used defines to make as little errors as possible... //non marking group #define NMG_S(s) "(?:"+s+")" #define NMG_S_0N(s) NMG_S(s)"*" #define NMG_S_1N(s) NMG_S(s)"+" #define NMG_S_01(s) NMG_S(s)"?" #define NMG(s) "(?:"s")" #define NMG_0N(s) NMG(s)"*" #define NMG_1N(s) NMG(s)"+" #define NMG_01(s) NMG(s)"?" #define RE_OR "|" #define RE_SPACE "[[:space:]]" #define RE_SPACE_01 RE_SPACE "?" #define RE_SPACE_0N RE_SPACE "*" #define RE_SPACE_1N RE_SPACE "+" #define RE_START_WORD "\\<" #define RE_END_WORD "\\>" #define RE_ID "[[:alpha:]]" NMG_0N("[_a-zA-Z0-9]") #define RE_CONST "const" #define RE_VOLATILE "volatile" #define RE_ANY "." #define RE_ANY_0N ".*" #define RE_ANY_1N ".+" #define RE_ANY_01 ".?" #define RE_PTR "\\*" #define RE_PTR_0N RE_PTR "*" #define RE_PTR_1N RE_PTR "+" #define RE_PTR_01 RE_PTR "?" #define RE_REF "&" #define RE_REF_0N RE_REF "*" #define RE_REF_1N RE_REF "+" #define RE_REF_01 RE_REF "?" #define RE_LINE_START "^" #define ONE_OF_PROTOCOLS NMG_S(strings::Name1) RE_OR NMG_S(strings::Name2) RE_OR NMG_S(strings::Name3) RE_OR \ NMG_S(strings::Name4) RE_OR NMG_S(strings::Name5) RE_OR NMG_S(strings::Name6) RE_OR \ NMG_S(strings::Name7) RE_OR NMG_S(strings::Name8) RE_OR NMG_S(strings::Name9) RE_OR \ NMG_S(strings::Name10) #define MATCH_PROTOCOL RE_START_WORD \ NMG_01(RE_ANY_0N "(" ONE_OF_PROTOCOLS ")" RE_ANY_0N) RE_OR \ NMG_01(RE_ANY_1N) \ RE_END_WORD RE_SPACE_0N Name1 to Name10 are static const std::string definitions within a class. A have the following regex defined to match params and function return type const boost::regex strings::regex_fct ( //possibly leading whitespace or const RE_LINE_START RE_SPACE_0N NMG_01(RE_CONST RE_SPACE_1N) //result type MATCH_PROTOCOL //return type can be a pointer or reference with const qualifier NMG_01(RE_CONST RE_SPACE_0N) RE_PTR_0N RE_SPACE_0N RE_REF_01 RE_SPACE_0N NMG_01(RE_CONST) RE_SPACE_1N //function name RE_START_WORD NMG_01(RE_ID) RE_END_WORD RE_SPACE_0N //function params "\\(" //open function params brace //param type (can be repeated 0 to N times) NMG_0N( RE_SPACE_0N MATCH_PROTOCOL RE_SPACE_0N //may be a ptr or ref type NMG_01(RE_CONST RE_SPACE_0N) RE_PTR_0N RE_SPACE_0N RE_REF_01 RE_SPACE_0N NMG_01(RE_CONST) RE_SPACE_1N //(?: still open //param name and default initializations are not important RE_ANY_0N //params can be comma separated in case of more then 1 param NMG_01(",") //close NMG_0N ) //terminate in "\\)" ); Now I have the following test string: using namespace std; string search_where_fct1("CName1_Setup const* someFct(){}"); set<string> uniques_names; find_protocols(search_where_fct1, strings::regex_fct, uniques_names); void find_protocols(const std::string& str, const boost::regex& expression, std::set<std::string>& log) { boost::smatch what; IdentifyProtocolUsage usage(log); if(boost::regex_match(str, what, expression, boost::match_extra)) //<<<<< crash!!!! { usage(what); } } This is the boost::regex function where it crashes: template <class BidiIterator, class Allocator, class traits> bool perl_matcher<BidiIterator, Allocator, traits>::match_imp() { // initialise our stack if we are non-recursive: #ifdef BOOST_REGEX_NON_RECURSIVE save_state_init init(&m_stack_base, &m_backup_state); used_block_count = BOOST_REGEX_MAX_BLOCKS; #if !defined(BOOST_NO_EXCEPTIONS) try{ #endif #endif // reset our state machine: position = base; search_base = base; state_count = 0; m_match_flags |= regex_constants::match_all; //LINE 162 perl_matcher_common.hpp !!! m_presult->set_size((m_match_flags & match_nosubs) ? 1 : re.mark_count(), search_base, last); m_presult->set_base(base); if(m_match_flags & match_posix) m_result = *m_presult; verify_options(re.flags(), m_match_flags); if(0 == match_prefix()) return false; return m_result[0].second == last; #if defined(BOOST_REGEX_NON_RECURSIVE) && !defined(BOOST_NO_EXCEPTIONS) } catch(...) { // unwind all pushed states, apart from anything else this // ensures that all the states are correctly destructed // not just the memory freed. while(unwind(true)){} throw; } #endif } Call from this line causes access violation: Unhandled exception at 0x104817fd in some_app.exe: 0xC0000005: Access violation writing location 0x56394ab7. I re-built regex with BOOST_REGEX_MATCH_EXTRA uncommented in user.hpp. Would be really nice to receive some comments or suggestions. With Kind Regards, Ovanes Markarian