title: Undefined reference when Gcc compiling Boost::regex with multiple versions of boost exist
body: <p>I was trying to install Boost on a linux machine(CentOs, Linux version 2.6.9-67.ELsmp).
  I followed with the instruction on Boost <a href="http://www.boost.org/doc/libs/1_49_0/more/getting_started/unix-variants.html#build-a-simple-program-using-boost">Getting Started</a> webpage.
  Downloaded and extracted the files, then I add prefix because I am not the root user.</p>
  
  <pre><code>./bootstrap.sh --prefix=/my_path/boost-1.49.0
  ./b2 install
  </code></pre>
  
  <p>I go to /my_path/boost-1.49.0 and check there are /include/boost/ and /lib/ contain files there.</p>
  
  <p>also I set LD_LIBRARY_PATH to /my_path/boost-1.49.0/lib/.</p>
  
  <p>To test if I installed successfully, I compile the following code:</p>
  
  <p>main.cpp</p>
  
  <pre><code>#include &lt;boost/regex.hpp&gt;
  #include &lt;iostream&gt;
  #include &lt;string&gt;
  
  using namespace boost;
  using namespace std;
  
  int main(int argc, char *argv[])
  {
      string line = "12345";
      regex pattern("^123");
      if (regex_match(line, pattern)) cout &lt;&lt; "match." &lt;&lt; endl;
      else cout &lt;&lt; "not match." &lt;&lt; endl;
      return 1;
  }
  </code></pre>
  
  <p>And compile by command:</p>
  
  <pre><code>g++ -v -I /my_path/boost-1.49.0/include/boost -L /my_path/boost-1.49.0/lib main.cpp -lboost_regex -o example
  </code></pre>
  
  <p>and generate following errors:</p>
  
  <pre><code>Reading specs from /usr/lib/gcc/x86_64-redhat-linux/3.4.6/specs
  Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-java-awt=gtk --host=x86_64-redhat-linux
  Thread model: posix
  gcc version 3.4.6 20060404 (Red Hat 3.4.6-9)
  /usr/libexec/gcc/x86_64-redhat-linux/3.4.6/cc1plus -quiet -v -I /my_path/boost-1.49.0/include/boost/ -D_GNU_SOURCE main.cpp -quiet -dumpbase main.cpp -mtune=k8 -auxbase main -version -o /tmp/ccW0ON8y.s
  ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../x86_64-redhat-linux/include"
  #include "..." search starts here:
  #include &lt;...&gt; search starts here:
  /my_path/boost-1.49.0/include/boost/
  /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../include/c++/3.4.6
  /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../include/c++/3.4.6/x86_64-redhat-linux
  /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../include/c++/3.4.6/backward
  /usr/local/include
  /usr/lib/gcc/x86_64-redhat-linux/3.4.6/include
  /usr/include
  End of search list.
  GNU C++ version 3.4.6 20060404 (Red Hat 3.4.6-9) (x86_64-redhat-linux)
          compiled by GNU C version 3.4.6 20060404 (Red Hat 3.4.6-9).
  GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
  as -V -Qy -o /tmp/ccpu82sB.o /tmp/ccW0ON8y.s
  GNU assembler version 2.15.92.0.2 (x86_64-redhat-linux) using BFD version 2.15.92.0.2 20040927
  /usr/libexec/gcc/x86_64-redhat-linux/3.4.6/collect2 --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o example /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../lib64/crt1.o /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../lib64/crti.o /usr/lib/gcc/x86_64-redhat-linux/3.4.6/crtbegin.o -L /my_path/boost-1.49.0/lib/ -L/usr/lib/gcc/x86_64-redhat-linux/3.4.6 -L/usr/lib/gcc/x86_64-redhat-linux/3.4.6 -L/usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../.. -L/lib/../lib64 -L/usr/lib/../lib64 /tmp/ccpu82sB.o -lboost_regex -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-redhat-linux/3.4.6/crtend.o /usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../../../lib64/crtn.o
  /tmp/ccpu82sB.o(.gnu.linkonce.t._ZN5boost11basic_regexIcNS_12regex_
  traitsIcEESaIcEEC1EPKcjRKS3_+0x27): In function `boost::basic_regex&lt;char, 
  boost::regex_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;::basic_regex(char const*, 
  unsigned int, std::allocator&lt;char&gt; const&amp;)':: 
  undefined reference to `boost::reg_expression&lt;char, boost::regex_traits&lt;char&gt;, 
  std::allocator&lt;char&gt; &gt;::reg_expression(char const*, unsigned int, 
  std::allocator&lt;char&gt; const&amp;)'
  
  /tmp/ccpu82sB.o(.gnu.linkonce.t.
  _ZN5boost11basic_regexIcNS_12regex_traitsIcEESaIcEED1Ev+0x11): In function 
  `boost::basic_regex&lt;char, boost::regex_traits&lt;char&gt;, 
  std::allocator&lt;char&gt;&gt;::~basic_regex()':
  : undefined reference to `boost::reg_expression&lt;char, boost::regex_traits&lt;char&gt;, 
  std::allocator&lt;char&gt; &gt;::~reg_expression()'
  /tmp/ccpu82sB.o(.gnu.linkonce.t.
  _ZN5boost9re_detail12perl_matcherIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub
  _matchIS6_EEENS_12regex_traitsIcEESaIcEEC1ES6_S6_RNS_13match_resultsIS6_S9_EERKNS_
  14reg_expressionIcSB_SC_EENS_15regex_constants12_match_flagsE+0xa1): In function 
  `boost::re_detail::perl_matcher&lt;__gnu_cxx::__normal_iterator&lt;char const*, 
  std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt;, 
  std::allocator&lt;boost::sub_match&lt;__gnu_cxx::__normal_iterator&lt;char const*, 
  std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt; &gt; &gt;, 
  boost::regex_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;
  ::perl_matcher(__gnu_cxx::__normal_iterator&lt;char const*, std::basic_string&lt;char, 
  std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt;, __gnu_cxx::__normal_iterator&lt;char 
  const*, std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt;, 
  boost::match_results&lt;__gnu_cxx::__normal_iterator&lt;char const*, std::basic_string&lt;char, 
  std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt;, 
  std::allocator&lt;boost::sub_match&lt;__gnu_cxx::__normal_iterator&lt;char const*, 
  std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt; &gt; &gt; &gt;&amp;, 
  boost::reg_expression&lt;char, boost::regex_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; const&amp;, 
  boost::regex_constants::_match_flags)':
  </code></pre>
  
  <p>however if I just compile with default boost that system administer installed</p>
  
  <pre><code>g++ -v main.cpp -lboost_regex -o example
  </code></pre>
  
  <p>Then it's fine.</p>
  
  <p>ldd example I got</p>
  
  <pre><code>libboost_regex.so.1 =&gt; /usr/lib64/libboost_regex.so.1 (0x0000002a95557000)
  </code></pre>
  
  <p>Due to some reason the I am asked not to update the boost in /usr/include/boost.
  Is there anything that can help me solve with this problem that install boost in a local folder and just change the path how to include and link to use different versions?</p>
  
  <p>I am not sure if this question is dumb or not, but I did search with google but mostly 
  related questions are not properly set -I, -L and -l in gcc command. I have no idea of 
  the error message above, really drive me mad. Any help is appreciated.</p>
  
  <p>Thanks for your patience and time.</p>