How to include gtk/gtk.h in a C file

Question

Im very new to development in C and would like to create a GUI using GTK. Ive already downloaded and installed gtk 3.6.4 bundle. Im trying to compile some example code like this:

#include <gtk/gtk.h>

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

I'm really having trouble understanding how to include the header files. I've seen a couple threads which discuss using a pkg-config command like :

pkg-config --cflags --libs gtk+-3.0

Where should this code be inserted? It runs on the command window and generates some output but this doesnt solve the error I get in MS visual studio in my code. I apologize in advance for repeating a question but I still am having trouble understanding where this pkg-config code should be run and that is not clear to me from the other responses.

Answer 1

The pkg-config line is a shell command that produces on standard output the compiler flags you would need to pass to use the function you want. For example,

pkg-config --cflags gtk+-3.0

produces for me

-pthread -I/usr/include/gtk-3.0 -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/gtk-3.0 -I/usr/include/gio-unix-2.0/ -I/usr/include/mirclient -I/usr/include/mircommon -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng12 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include 

What you want to do is use a feature of your shell in which the output of a command is dropped into the command line of another one. In bash, this is done with `...`:

gcc -o program program.c `pkg-config --cflags --libs gtk+-3.0`

For bash, another syntax is $(...):

gcc -o program program.c $(pkg-config --cflags --libs gtk+-3.0)

For GNU make makefiles, if you want to use $(...), you will need to use the shell function:

gcc -o program program.c $(shell pkg-config --cflags --libs gtk+-3.0)

--cflags produces the C compiler flags, --libs produces the linker flags. If you're building using a makefile, you'll want to only provide --cflags to the recipe that produces the .o files and only provide --libs to the recipe that produces the final executable. For compiling a single C file directly into an executable with a single command, provide both.