[SOLVED] undefined reference to `gtk_init'

CollieJim · 07-11-2019, 12:38 AM

I am trying to compile a test GTK program following instructions in the "C_GUI_Programming" document found at https://www.raspberrypi.org/magpi/is...i-programming/ Page 77. I have installed libgtk2.0 and libgtk2.0-dev.
The code:

Code:

#include <gtk/gtk.h>

int main ( int argc, char *argv[] )
{
    gtk_init ( &argc, &argv );
    GtkWidget *win = gtk_window_new ( GTK_WINDOW_TOPLEVEL );
    gtk_widget_show ( win );
    gtk_main ( );
    return 0;
}

Code:

$ gcc `pkg-config --cflags --libs gtk+-2.0` gtktest.c -o gtktest
/tmp/ccQtPQqB.o: In function `main':
gtktest.c:(.text+0x12): undefined reference to `gtk_init'
gtktest.c:(.text+0x18): undefined reference to `gtk_window_new'
gtktest.c:(.text+0x20): undefined reference to `gtk_widget_show'
gtktest.c:(.text+0x24): undefined reference to `gtk_main'
collect2: error: ld returned 1 exit status

The output from pkg-confg follows. I have replaced spaces with newlines to make readable.

Code:

$ pkg-config --cflags --libs gtk+-2.0
-pthread
-I/usr/include/gtk-2.0
-I/usr/lib/arm-linux-gnueabihf/gtk-2.0/include
-I/usr/include/gio-unix-2.0/
-I/usr/include/cairo
-I/usr/include/pango-1.0
-I/usr/include/atk-1.0
-I/usr/include/cairo
-I/usr/include/pixman-1
-I/usr/include/gdk-pixbuf-2.0
-I/usr/include/libpng16
-I/usr/include/pango-1.0
-I/usr/include/harfbuzz
-I/usr/include/pango-1.0
-I/usr/include/glib-2.0
-I/usr/lib/arm-linux-gnueabihf/glib-2.0/include
-I/usr/include/freetype2
-I/usr/include/libpng16
-I/usr/include/freetype2
-I/usr/include/libpng16
-lgtk-x11-2.0
-lgdk-x11-2.0
-lpangocairo-1.0
-latk-1.0
-lcairo
-lgdk_pixbuf-2.0
-lgio-2.0
-lpangoft2-1.0
-lpango-1.0
-lgobject-2.0
-lglib-2.0
-lfontconfig
-lfreetype

What's missing?

astrogeek · 07-11-2019, 01:15 AM

Have a look at this thread on StackOverflow.

From that thread:

Quote:

Objects that want symbol definitions must be linked before the objects that provide the definitions.

As linked, from man ld

Quote:

The linker will search an archive only once, at the location where it is specified on the command line. If the archive defines a symbol which was undefined in some object which appeared before the archive on the command line, the linker will include the appropriate file(s) from the archive. However, an undefined symbol in an object appearing later on the command line will not cause the linker to search the archive again.

Move the --libs after the object file has been created.

NevemTeve · 07-11-2019, 03:05 AM

`ld` has been recently changed, the order of objects and libraries now matters, so try this:

Code:

gcc `pkg-config --cflags` gtktest.c -o gtktest `pkg-config--libs gtk+-2.0`