#include <iostream>
#include <string>
#include <boost/regex.hpp>  // Boost.Regex lib

using namespace std;

int main( ) {

  std::string s,sre;

  //regular expression with [:xdigit:]
  sre="[:xdigit:]*page[:xdigit:]*error[:xdigit:]";//why :xdigit: doesnot match ??
  //regular expression with \w
  //sre="\\w*page\\w*error\\w"; //generates match OK

  //Matching string
  s="###############################1PAGE1ERROR1########################";

  boost::regex re;
  re.assign(sre, boost::regex_constants::icase);

  std::string::const_iterator start, end;
  start = s.begin();
  end = s.end();
  boost::sregex_iterator it(start, end, re);
  boost::sregex_iterator it_end;

  for( ; it != it_end; it++)
    {
      cout << "Found Pattern:start:" << std::string((*it)[0].first, (*it)[0].second) << ":end:\n" 
	   << "Pattern starts at :" << (*it)[0].first - s.begin()  
	   << "\nPattern ends at: " << ((*it)[0].second - 1) - s.begin() 
	   << "\nPattern length:" << (*it)[0].length() << endl;
    }

}