compiling simple code with boost::regex

Question

I'm having trouble compiling the following code:

#include <iostream>
#include <string>
#include <boost/regex.hpp>

using namespace std;

int main()
{
  string s;
  boost::regex re("^{(APPLE|ORANGE),(\\d*)}$");
  boost::cmatch matches;

  while(true)
  {
    cout << "String: ";
    cin >> s;
    if(boost::regex_match(s.c_str(), matches, re))
    {
      for(int i=1; i<matches.size(); i++)
      {
        string match(matches[i].first, matches[i].second);
        cout << "match[" << i << "]:  " << matches[i] << endl;
      }

    }
    else
    {
      cout << "no match" << endl;
    }
  }
  return 0;

}

I used the following line to compile with g++:

g++ regexp_test.cpp -o regexp_test.o

also tried:

g++ -lboost_regex regexp_test.cpp -o regexp_test.o

but I'm getting this long error:

/tmp/ccyEpQIk.o: In function bool boost::regex_match<char const*, std::allocator<boost::sub_match<char const*> >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)': regexp_test.cpp:(.text._ZN5boost11regex_matchIPKcSaINS_9sub_matchIS2_EEEcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEEbT_SA_RNS_13match_resultsISA_T0_EERKNS_11basic_regexIT1_T2_EENS_15regex_constants12_match_flagsE[bool boost::regex_match<char const*, std::allocator<boost::sub_match<char const*> >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)]+0x4c): undefined reference toboost::re_detail::perl_matcher >, boost::regex_traits > >::match()' /tmp/ccyEpQIk.o: In function boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)': regexp_test.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)]+0x22): undefined reference toboost::basic_regex > >::do_assign(char const*, char const*, unsigned int)' /tmp/ccyEpQIk.o: In function boost::re_detail::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*)': regexp_test.cpp:(.text._ZN5boost9re_detail12perl_matcherIPKcSaINS_9sub_matchIS3_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC2ES3_S3_RNS_13match_resultsIS3_S6_EERKNS_11basic_regexIcSA_EENS_15regex_constants12_match_flagsES3_[_ZN5boost9re_detail12perl_matcherIPKcSaINS_9sub_matchIS3_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC5ES3_S3_RNS_13match_resultsIS3_S6_EERKNS_11basic_regexIcSA_EENS_15regex_constants12_match_flagsES3_]+0xb3): undefined reference toboost::re_detail::perl_matcher >, boost::regex_traits > >::construct_init(boost::basic_regex > > const&, boost::regex_constants::_match_flags)' collect2: ld returned 1 exit status

what am I doing wrong?

perreal perreal · Accepted Answer · 2012-07-15T06:17:18

Perhaps you don't have the boost binaries, the code compiles here with -lboost_regex. Also, curly brackets are for repeating patterns. For example \d{3} means three digits so you may need to change your regex to:

boost::regex re("^(APPLE|ORANGE),(\\d*)$");

compiling simple code with boost::regex

2 Answers