Hi, I have two problems that I would need some help. Thanks in advance. Question 1: Please consider the regular expression to match US phone number below: ((\(\d{3}\)?)|(\d{3}))([\s-./]?)(\d{3})([\s-./]?)(\d{4}) boost doesn't like it and it will throw an exception for the code below while it seems to be fine in online regex tester and .Net Regex library. I don't know what is imcompatiable with boost regex library. Please advice. try { boost::wregex expr(csRegex, boost::regex::normal | boost::regbase::icase); } catch (boost::exception const& e) { } Question 2: Please consider the regular expression to match US SSN below: (?!000)([0-6]\d{2}|7([0-6]\d|7[012])) ([ -])? (?!00)\d\d([ -|])? (?!0000)\d{4} It didn't throw an exception for this regular expression but it wasn't able to match any SSN at all in any format while it matches fine using other regular expression engine. Am I missing something? if (expr.expression()) { // Boost Regex usage flags boost::regex_constants::match_flag_type flags = boost::regex_constants::match_normal; // Start the boost regular expression iterator boost::wcregex_iterator start(boost::make_regex_iterator (StringToMatch, expr, flags)), end; while (start != end) { boost::match_results<const wchar_t*> match = *start; . . . } }