On Thu, Feb 17, 2005 at 01:05:43PM +0100, Gert Cuykens wrote: > static void callback( GtkWidget *widget, gpointer data ){ > g_print ("Hello again - %s was pressed\n", (gchar *) data); > } > > why do they put () around gchar ?
In C, it's called a cast. > why can it not be gchar *data ? Because that would be invalid C, a syntax error. > What does %s do ? It's a format specifier, it gets replaced with the string data points to. See 'man printf' for details. > Are gpointer and gchar global variables of gtk ? > Are gpointer and gchar data types or objects ? They're basic types of GLib. See http://developer.gnome.org/doc/API/2.0/glib/glib-Basic-Types.html > What does gpointer and gchar represent ? Well, gpointer represents a generic pointer and gchar represents a character corresponding to the standard C char type. I suggest that you get a good book on C programming so that you get at first familiar with the language before you start programming with GTK. Beginner questions for C are a bit off topic on this ML, I think. HTH -- Claudio _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list