Re: easy gtk-programm fault

[Axel Simon <A Simon kent ac uk>]

On Tue, 2006-01-17 at 15:29 +0100, Daniel Dieterle wrote:
> hallo everybody,
>
> since some days i try to code my first gtk program. it 's not more than 
> a window with a label in it.
> the code is that:
> > #include <gtk/gtk.h>
> >
> >
> > int main( int argc,
> >                 char *argv[] )
> > {
> >         GtkWidget *window1;
> >         GtkWidget *label1;
> >         
> >         gtk_init (&argc, &argv);
> >
> >         window1 = gtk_window_new (GTK_WINDOW_TOPLEVEL);
> >         label1 = gtk_label_new ("Hallo Du");
> >
> >         gtk_container_add (GTK_CONTAINER (window1), label1);
> >         
> >         gtk_widget_show (label1);
> >         gtk_widget_show (window1);      
> >
> > //     sleep(1);
> > //      gtk_label_set_text (label1,"wie gehts?");
> >         
> >         gtk_main ();
> >
> >         return 0;
> > }
>
> there is no thing to warry about.
> but my aim is to change the text in the label. and if i uncomment the 
> "gkt_label_set_text ..."-line, gcc (gcc label.c `pkg-config --cflags 
> --libs gtk+-2.0`) shows a warning:
> > label.c: In Funktion ÂmainÂ:
> > label.c:22: Warnung: Verarbeiten des Argumentes 1 von Âgtk_label_set_text von inkompatiblem Zeigertyp
> which means that the "label1" in the "set_text"-line is a incompatible 
> pointertype, i think.
>
> do anybody know, what i'm doing wrong?

You should declare the label1 variable as GtkLabel*. The compiler
complains because you use a more general GtkWidget pointer as GtkLabel
pointer.

Besides, the program will not display the original text, since the main
loop must be run to display anything. Consider defining a call back that
sets the label. Then you can tell Gtk to call that call back after 1s
using g_timeout_add:

http://developer.gnome.org/doc/API/2.0/glib/glib-The-Main-Event-
Loop.html#g-timeout-add

Axel.