Hi, When i run my C++ program which is using boost library, i am getting these errors main.o: In function `boost::program_options::variables_map::operator[](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const': /usr/local/include/boost-1_35/boost/program_options/variables_map.hpp:161: undefined reference to `boost::program_options::abstract_variables_map::operator[](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const' /usr/local/include/boost-1_35/boost/program_options/variables_map.hpp:161: undefined reference to `boost::program_options::abstract_variables_map::operator[](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const' /usr/local/include/boost-1_35/boost/program_options/variables_map.hpp:161: undefined reference to `boost::program_options::abstract_variables_map::operator[](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const' /usr/local/include/boost-1_35/boost/program_options/variables_map.hpp:161: undefined reference to `boost::program_options::abstract_variables_map::operator[](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const Please help to solve this problem. Please... -- Thanks & Regards Nagendar