2

I am quite new to C++ and I was trying to learn regular expressions using the Boost library. I am trying the following simple code.

#include <cstdlib>
#include <iostream>
#include <cstring>
#include <boost/regex.hpp>

using namespace std;
using namespace boost;

/*
 * 
 */
int main()
{
    const regex expression( "How to re" );

    string string1 = "How to re";

    bool match=regex_match(string1,expression);

    if (match){
        cout<<"Yes"<<endl;
    }

    return 0;
}

The problem is that a huge error is flagged when I try to run the file from the terminal. The error flagged is the following:

Undefined symbols:
  "boost::re_detail::get_mem_block()", referenced from:
      boost::re_detail::save_state_init::save_state_init(boost::re_detail::saved_state**, boost::re_detail::saved_state**)in ccqa7fIw.o
      boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::extend_stack()in ccqa7fIw.o
  "boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >::maybe_assign(boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > > const&)", referenced from:
      boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::match_match()in ccqa7fIw.o
  "boost::re_detail::get_default_error_string(boost::regex_constants::error_type)", referenced from:
      boost::re_detail::cpp_regex_traits_implementation<char>::error_string(boost::regex_constants::error_type) constin ccqa7fIw.o
      boost::re_detail::cpp_regex_traits_implementation<char>::error_string(boost::regex_constants::error_type) constin ccqa7fIw.o
  "boost::re_detail::put_mem_block(void*)", referenced from:
      boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::unwind_extra_block(bool)in ccqa7fIw.o
      boost::re_detail::save_state_init::~save_state_init()in ccqa7fIw.o
  "boost::re_detail::raise_runtime_error(std::runtime_error const&)", referenced from:
      void boost::re_detail::raise_error<boost::regex_traits_wrapper<boost::regex_traits<char, boost::cpp_regex_traits<char> > > >(boost::regex_traits_wrapper<boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::error_type)in ccqa7fIw.o
  "boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, 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)", referenced from:
      boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, __gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >&, 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::basic_string<char, std::char_traits<char>, std::allocator<char> > >)in ccqa7fIw.o
  "boost::re_detail::cpp_regex_traits_implementation<char>::transform_primary(char const*, char const*) const", referenced from:
      boost::cpp_regex_traits<char>::transform_primary(char const*, char const*) constin ccqa7fIw.o
  "boost::re_detail::cpp_regex_traits_implementation<char>::transform(char const*, char const*) const", referenced from:
      boost::cpp_regex_traits<char>::transform(char const*, char const*) constin ccqa7fIw.o
  "boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)", referenced from:
      boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)in ccqa7fIw.o
  "boost::re_detail::verify_options(unsigned int, boost::regex_constants::_match_flags)", referenced from:
      boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find_imp()in ccqa7fIw.o
  "boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find()", referenced from:
      bool boost::regex_search<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, __gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::match_results<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >&, 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::basic_string<char, std::char_traits<char>, std::allocator<char> > >)in ccqa7fIw.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

I really cannot understand what is going on here; I was also looking at examples of regex codes from other threads but couldn't find any solution. Can you please help me? Thanks!

4

1 回答 1

3

您不与 Boost 正则表达式库链接，它不仅是标题，而且还有一个您必须链接的库。

尝试

$ c++ -I $PATH/boost_1_52_0 filename.cpp -o filename -L$PATH/to/libraries -lboost_regex

您还必须设置库的路径，因为您似乎使用了自定义构建的 Boost。

于 2013-02-07T13:36:59.853 回答