How to include/link boost::regex library?

Question

I am trying to use the boost regex library but I can't manage to compile my program. All related questions which involve similar error messages seem to relate to situations where regex library wasn't properly linked. I think that I am linking it, but maybe I am doing something stupid... Perhaps someone sees my mistake?
Here is my test program:

// ~/workspace/test/test.cpp
#include <string>
#include <iostream>
#include <boost/regex.hpp>
int main(){
   std::string s("abaab");
   boost::regex r("[ab]*");
   std::cout << boost::regex_match(s,r) << std::endl;   
}

Here are the boost binaries (I installed them via synaptic on Xubuntu):

  /usr/lib/i386-linux-gnu$ ls libboost_regex* -al
  -rw-r--r-- 1 root root 2169582 Okt 13 05:14 libboost_regex.a
  lrwxrwxrwx 1 root root      24 Okt 13 05:13 libboost_regex.so -> libboost_regex.so.1.53.0
  -rw-r--r-- 1 root root 1002568 Okt 13 05:14 libboost_regex.so.1.53.0  

Nevertheless I'm getting quite an ugly error message when running

~/workspace/test$ g++ -L/usr/lib/i386-linux-gnu/ -lboost_regex test.cpp  

Here is the complete message:

  ~/workspace/test$ g++ -L/usr/lib/i386-linux-gnu/ -lboost_regex test.cpp 
  /tmp/cc1yDf0v.o: In function `bool boost::regex_match<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)':
  test.cpp:(.text._ZN5boost11regex_matchIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS5_EEEcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEEbT_SD_RNS_13match_resultsISD_T0_EERKNS_11basic_regexIT1_T2_EENS_15regex_constants12_match_flagsE[_ZN5boost11regex_matchIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS5_EEEcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEEbT_SD_RNS_13match_resultsISD_T0_EERKNS_11basic_regexIT1_T2_EENS_15regex_constants12_match_flagsE]+0x4c): undefined reference to `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::match()'
  /tmp/cc1yDf0v.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)':
  test.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[_ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j]+0x22): undefined reference to `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)'
  /tmp/cc1yDf0v.o: In function `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(__gnu_cxx::__normal_iterator<char const*, std::string>, __gnu_cxx::__normal_iterator<char const*, std::string>, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, __gnu_cxx::__normal_iterator<char const*, std::string>)':
  test.cpp:(.text._ZN5boost9re_detail12perl_matcherIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS6_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC2ES6_S6_RNS_13match_resultsIS6_S9_EERKNS_11basic_regexIcSD_EENS_15regex_constants12_match_flagsES6_[_ZN5boost9re_detail12perl_matcherIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS6_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC5ES6_S6_RNS_13match_resultsIS6_S9_EERKNS_11basic_regexIcSD_EENS_15regex_constants12_match_flagsES6_]+0xcd): undefined reference to `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::string>, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init(boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)'
  collect2: error: ld returned 1 exit status

The header seems to be found, right? How else could gcc know about boost::re_detail::perl_matcher or boost::basic_regex?
I have no clue what the problem might be. Maybe it is the linking after all? Thanks in advance!

Answer 1

You just needed to make sure the library comes after your own sources.

g++ -L/usr/lib/i386-linux-gnu/ test.cpp -lboost_regex 

This is a FAQ:

• Why does the order in which libraries are linked sometimes cause errors in GCC?
• g++ linking order dependency when linking c code to c++ code

And probably quite a few more. I guess it's (sadly) one of those rites-of-passage that goes with the territory :(