linking to boost regex in gcc

Question

i am trying to compile my program which uses regex on linux. I built the boost library in the libs/regex/build by typing make -fgcc.mak which created a directory gcc which contains the following four files

boost_regex-gcc-1_35
boost_regex-gcc-d-1_35
libboost_regex-gcc-1_35.a
libboost_regex-gcc-d-1_35.a

Now I want to use regex from my program which is in some arbitrary directory. I #included boost/regex.hpp

I got the error which stated that regex.hpp is not found. Then I gave the -I option in the g++ compiler. I didn't get that error. But I get the following error

undefined reference to `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)'

I googled and found that I need to somehow link one of the above 4 libraries to my program. How can I do it. Which one should I link and why?

Answer 1

Either add libboost_regex-gcc-1_35.a to your list of object files in your link step or add -static -lboost_regex-gcc-1_35 to the same. Also be sure that you have an -I switch pointing to your boost includes directory in your compile step. If the libraries are outside the typical search path (/usr/lib on *nix), add that directory to your link command with -Wl,-L/path/to/boost/libs for g++ or simply -L/path/to/boost/libs on ld.

Answer 2

I also faced similar problems when using boost filesystem. Here's what I needed to do to get it to link statically.

Excerpt from My Original (problematic) Makefile: LIBS = -static -lboost_filesystem

Solution: LIBS = -Wl,-Bstatic -lboost_filesystem -lboost_system -Wl,-Bdynamic

You can view the complete Makefile from http://code.google.com/p/neptuner/source/browse/codebase/trunk/stratego/uboat/Makefile

Needed to add boost_system to make it link properly. Direct addition/specification of libboost*.a created more problems. Note the -Bdynamic is present to prevent static link of standard libraries.