Hi Boost_UsersAll, I am trying to compile "...\libs\program_options\example\first.cpp" with VC6.0(sp6) and when I do it I get the following errors. I am sure that Boost1.33.0 has been successfully installed on my Windows XP machine. Any ideas/suggestions would be very helpful! Best regards！ ///////////////////////////////////////////////////////////////////////////////////// d:\work\algos\boost\boost_1_33_0\boost\program_options\options_description.hpp(156) : error C2258: illegal pure syntax, must be '= 0' d:\work\algos\boost\boost_1_33_0\boost\program_options\options_description.hpp(156) : error C2252: 'm_default_line_length' : pure specifier can only be specified for functions d:\work\algos\boost\boost_1_33_0\boost\program_options\options_description.hpp(159) : error C2065: 'm_default_line_length' : undeclared identifier d:\work\mfa\codes\libcleml_1.0.1\mfa_tests\first.cpp(27) : error C2660: 'parse_command_line' : function does not take 3 parameters d:\work\mfa\codes\libcleml_1.0.1\mfa_tests\first.cpp(37) : fatal error C1903: unable to recover from previous error(s); stopping compilation Error executing cl.exe. first.obj - 5 error(s), 0 warning(s)