How do I link GLFW

Question

I am trying to link GLFW to my C program.

The docs seem to suggest #include<GLFW/glfw3.h> however I have installed 2.7.2 (from my distro's repository) and don't have that header file:

find / -name *glfw* 2> /dev/null
/usr/lib/libglfw.so.2.6
/usr/lib/libglfw.a
/usr/lib/libglfw.so
/usr/lib/pkgconfig/libglfw.pc
/usr/lib/libglfw.so.2
/usr/include/GL/glfw.h
/usr/share/doc/libglfw-dev
/usr/share/doc/libglfw2
/var/cache/apt/archives/libglfw2_2.7.2-1_i386.deb
/var/cache/apt/archives/libglfw-dev_2.7.2-1_i386.deb
/var/lib/dpkg/info/libglfw2.list
/var/lib/dpkg/info/libglfw2.postinst
/var/lib/dpkg/info/libglfw-dev.md5sums
/var/lib/dpkg/info/libglfw2.postrm
/var/lib/dpkg/info/libglfw2.md5sums
/var/lib/dpkg/info/libglfw2.shlibs
/var/lib/dpkg/info/libglfw-dev.list

I tried #include<GL/glfw.h> but I still get undefined reference to 'glfwLoadTexture2D'

How do I link to GLFW and use glfwLoadTexture2D()?

Answer 1

An #include does nothing for the linker; it just brings in declarations, not the actual functions.

The documentation indicates that GLFW uses pkg-config (not surprising; @elmindreda knows her stuff), so your compilation line should be something like:

$ cc `pkg-config --cflags glfw3` -o foo foo.c `pkg-config --static --libs glfw3`

Also note that since the library uses pkg-config, you're not supposed to "care" about details such as where the header and library files are located on your particular installation. Just ask using the --cflags and --libs modes, and you will get the proper locations returned, as the example above indicates.

Answer 2

You are mixing up compilation and linking. If you were missing headers, you would probably have errors a lot sooner than the linking stage.

"Undefined reference" results from symbols not being found by the linker. The most likely cause is you not telling gcc that it should link to the GLFW libraries:

 gcc myfile.c -lglfw