Hello all, i am using boost regex to check the syntax of a URL. the regex is as :- static const char *URLSYNTAXREGEX = "^((file|https?|ftp)://)?(([-a-zA-Z0-9_]+[.]{1})+(([-a-zA-Z0-9]+))([:]{1}([0-9]+)){0,1})([?/][^[:space:]]*)?" the function for evaluation is:- bool URLHandler::EvaluateRegex(const char *regularexp,std::string url){ boost::smatch what; boost::regex exp(regularexp,boost::regex::extended); boost::regex_search(url,what,exp); std::string search=(std::string)what[0]; if(search.length() == url.length()) { return true; } else { return false; } } when i am running this code with single thread it is running fine. But when i am integrating this code with a multithreaded application it is giving this error:- terminate called after throwing an instance of 'boost::regex_error' what(): Invalid content of repeat range Aborted Can you please help me in this. Its very urgent for me. Thanks. Yogendra --------------------------------- Do you Yahoo!? Everyone is raving about the all-new Yahoo! Mail Beta.