What is wrong with this usage of boost regex library?

Question

Here is the code;

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

using boost::regex;
using boost::regex_match;

int main(int argc, char **argv) {
    std::string input;
    regex gdreg(R"(g[a-z]+d)");
    while(true)
    {
        std::cout << "Give me a word: ";
        std::cin >> input;
        if(input == "q") {
            break;
        }
        if(regex_match(input, gdreg))
            std::cout << "It's a GD word!" << std::endl;
        else
            std::cout << "Nooooooo!" << std::endl;
    }
}

Here is the error msg:

g++ x.cpp -std=c++11 -o x
/tmp/ccJ7zdHo.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)':
x.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]+0x77): 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/ccJ7zdHo.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)':
x.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[_ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j]+0x2a): 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/ccJ7zdHo.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>)':
x.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_]+0x10b): 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

Not using raw string does not solve the problem.

peterh · Accepted Answer · 2021-02-25 09:29:33Z

13

I don't know - maybe undefined reference to 'boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)'?

Reading this error message isn't fun, for sure, but it contains all the info you need - provided you are aware of the meaning of terms like reference to and ld, and you are capable of structuring the message into parts:

ld returned 1 exit status: the linker is unhappy
/tmp/.... .o: I'm creating an object file.
but in function boost::basic_regex<...>::assign (the context)
undefined reference to boost::cpp_regex_traits<...>::do_assign(...) (the problem)

The linker doesn't see where to get the do_assign function code from. This is often caused by forgetting to add the library containing the code, e.g. -lboost_regex.

Also cfr. https://stackoverflow.com/a/559191/6610

edited Feb 25, 2021 at 9:29

peterh

1

answered Feb 18, 2014 at 19:16

xtofl

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Comments

Dasha · Accepted Answer · 2016-06-04 17:42:52Z

5

It is solved by just adding the -lboost_regex to the compiling line so:

This works: $ g++ main.cc -o main -lboost_regex

source: http://ubuntuforums.org/archive/index.php/t-1674703.html

for my case this solution worked :)

answered Jun 4, 2016 at 17:42

Dasha

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Comments

Eli Harper · Accepted Answer · 2019-08-29 14:33:44Z

0

In my case, I had to add /boost//libboost-regex to the Jamfile in that directory.

I'm sorry that you asked this question so long ago and haven't found the answer, but I hope this helps!

answered Aug 29, 2019 at 14:33

Eli Harper

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