Question

I receiving a undefined reference error when try to compile an c++ program. I’m the using the -I and -L switches to point to lib and include files my command:

g++ -g  -Wall -L/usr/local/lib/active -I/usr/local/include/active tutorial_01.cpp -o tutorial_01

Can some help me with what I’m missing?

    In file included from /usr/local/include/active/jaus/core/header.h:44:0,
                 from /usr/local/include/active/jaus/core/message.h:49,
                 from /usr/local/include/active/jaus/core/service.h:44,
                 from /usr/local/include/active/jaus/core/transport/transport.h:44,
                 from /usr/local/include/active/jaus/core/component.h:43,
                 from tutorial_01.cpp:42:
/usr/local/include/active/jaus/core/address.h: In static member function ‘static bool JAUS::Address::IsReservedComponentID(JAUS::Byte)’:
/usr/local/include/active/jaus/core/address.h:302:40: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
/usr/local/include/active/jaus/core/address.h:303:40: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
/tmp/cczAJw8H.o: In function `main':
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:58: undefined reference to `JAUS::Component::Component()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:78: undefined reference to `JAUS::Discovery::Name'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:78: undefined reference to `JAUS::Component::GetService(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:88: undefined reference to `JAUS::Discovery::SetSubsystemIdentification(JAUS::Subsystem::Type, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:100: undefined reference to `JAUS::Component::Initialize(JAUS::Address const&, double)'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:109: undefined reference to `CxUtils::Time::GetUtcTimeMs()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:122: undefined reference to `JAUS::Management::Name'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:122: undefined reference to `JAUS::Component::GetService(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:130: undefined reference to `CxUtils::Time::GetUtcTimeMs()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:136: undefined reference to `CxUtils::Time::GetUtcTimeMs()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:139: undefined reference to `CxUtils::GetChar()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:144: undefined reference to `CxUtils::SleepMs(unsigned int)'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:150: undefined reference to `JAUS::Component::Shutdown()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:58: undefined reference to `JAUS::Component::~Component()'
/home/reese/JAUS++-2.110519-src/libraries/jaus++/2.0/src/jaus/core/tutorial_01.cpp:58: undefined reference to `JAUS::Component::~Component()'
collect2: ld returned 1 exit status

Answer 1

The -L option doesn’t really do anything for you unless you also use -l with the name of the library. I’m going to take a guess that your library is named libactive.a, in which case you’ll want to do this:

g++ -g -Wall -L/usr/local/lib/active -lactive -I/usr/local/include/active tutorial_01.cpp -o tutorial_01

If the library has a different name, you’ll need to change it.

Here’s the rule: For a library called /path/to/library/libmylibrary.a, use this command line: -L/path/to/library -lmylibrary.