Undefined symbols for architecture x86_64

[lukywong]

Hi, I tried to compile one of the examples on mac os x 10.11, but i got below error.
$ g++ -o main captcha.cpp
Undefined symbols for architecture x86_64:
"_XAllocClassHint", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XCheckMaskEvent", referenced from:
cimg_library::CImgDisplay::events_thread(void) in captcha-e2d6a3.o
"_XCheckTypedEvent", referenced from:
cimg_library::CImgDisplay::events_thread(void) in captcha-e2d6a3.o
"_XCheckWindowEvent", referenced from:
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XCloseDisplay", referenced from:
cimg_library::CImgDisplay::screen_width() in captcha-e2d6a3.o
cimg_library::CImgDisplay::screen_height() in captcha-e2d6a3.o
"_XCreateColormap", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XCreateImage", referenced from:
void cimg_library::CImgDisplay::_resize(unsigned char, unsigned int, unsigned int, bool) in captcha-e2d6a3.o
void cimg_library::CImgDisplay::_resize(unsigned short, unsigned int, unsigned int, bool) in captcha-e2d6a3.o
void cimg_library::CImgDisplay::_resize(unsigned int, unsigned int, unsigned int, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
"_XCreateSimpleWindow", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XCreateWindow", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
"_XDestroyWindow", referenced from:
cimg_library::CImgDisplay::assign() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_desinit_fullscreen() in captcha-e2d6a3.o
"_XFree", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XFreeColormap", referenced from:
cimg_library::CImgDisplay::assign() in captcha-e2d6a3.o
"_XGetVisualInfo", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XGetWindowAttributes", referenced from:
cimg_library::CImgDisplay::resize(int, int, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_map_window() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XGrabKeyboard", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XInternAtom", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XLookupString", referenced from:
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XMapRaised", referenced from:
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_map_window() in captcha-e2d6a3.o
"_XMoveWindow", referenced from:
cimg_library::CImgDisplay::move(int, int) in captcha-e2d6a3.o
"_XOpenDisplay", referenced from:
cimg_library::CImgDisplay::screen_width() in captcha-e2d6a3.o
cimg_library::CImgDisplay::screen_height() in captcha-e2d6a3.o
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XPutImage", referenced from:
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_paint(bool) in captcha-e2d6a3.o
"_XQueryKeymap", referenced from:
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XResizeWindow", referenced from:
cimg_library::CImgDisplay::resize(int, int, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XSelectInput", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
"_XSendEvent", referenced from:
cimg_library::CImgDisplay::_paint(bool) in captcha-e2d6a3.o
"_XSetClassHint", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XSetInputFocus", referenced from:
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XSetWMProtocols", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XSetWindowColormap", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XStoreColors", referenced from:
cimg_library::CImgDisplay::_set_colormap(unsigned long&, unsigned int) in captcha-e2d6a3.o
"_XStoreName", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XSync", referenced from:
cimg_library::CImgDisplay::assign() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_map_window() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XUngrabKeyboard", referenced from:
cimg_library::CImgDisplay::_desinit_fullscreen() in captcha-e2d6a3.o
"_XUnmapWindow", referenced from:
cimg_library::CImgDisplay::_handle_events(XEvent const) in captcha-e2d6a3.o
"_XVisualIDFromVisual", referenced from:
cimg_library::CImgDisplay::assign(unsigned int, unsigned int, char const, unsigned int, bool, bool) in captcha-e2d6a3.o
"_XWindowEvent", referenced from:
cimg_library::CImgDisplay::_init_fullscreen() in captcha-e2d6a3.o
cimg_library::CImgDisplay::_map_window() in captcha-e2d6a3.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[dtschump]

Looks like you forgot to link your code with the X11 library:

$ g++ -o foo foo.cpp -lX11 -lpthread

or, if you don't have X11 installed and if you don't want display capabilities of CImg:

$ g++ -o foo foo.cpp -Dcimg_display=0

[lukywong]

Thank you, all ok after installing x11

[caiyzik]

I tried doing this to no avail. I also used -L/opt/X11 and I still get the same errors

[devernay]

@trmontgomery did you install xquartz ? (google it)

[caiyzik]

@devernay Yes I did.

[devernay]

did you use this compile line:

clang++ -I .. -I /opt/X11/include captcha.cpp -L /opt/X11/lib -lX11 -o captcha

[caiyzik]

@devernay Wow that worked! Any idea on why I can't compile with g++? (Edit: Apparently the gcc that comes with Mac is just clang...)