Hi, Is there any special steps to link a *.cpp to a library created and compiled with C compiler? I have a class that calls a C function in an existing library (libXX.so). This library is written in C. I got the following error while compiling, and I think it happens during linking: =========== cincai@haha:~/tmp/msg++/src> g++ -I../include \ -L/home/cincai/tmp/grimpsim/lib -lsimgrid Host.cpp /tmp/ccfjw59W.o(.text+0x76): In function `Host::Host[not-in-charge](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, double)': : undefined reference to `MSG_host_create(char const*, char*, double, void*)' ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ /tmp/ccfjw59W.o(.text+0x15a): In function `Host::Host[in-charge](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, double)': : undefined reference to `MSG_host_create(char const*, char*, double, void*)' ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ collect2: ld returned 1 exit status =========== The content of /home/cincai/tmp/grimpsim/lib is: =========== libsimgrid.a libsimgrid.la libsimgrid.so libsimgrid.so.0 libsimgrid.so.0.0.1 =========== -- -- Verdi March --