Hi Kristian,
Thank you and Mr Liu.
Thanks for your explicit instrument.
> On Fri, Dec 25, 2009 at 9:14 AM, Randy <randyqiuxy@xxxxxxxxxxx> wrote:
> > {
> > const gchar *textLabel=gtk_label_get_text(GTK_LABEL(label));
> > const gchar *textWindow=gtk_window_get_title(GTK_WINDOW(window));
> >
> > if(keyEvent->keyval==GDK_Shift_L)
> > {
> > //surprise,if I skip(via "//") one of the two lines, another
> > //will work fine.....
> > gtk_window_set_title(GTK_WINDOW(window),textLabel);
> > gtk_label_set_text(GTK_LABEL(label),textWindow);
> > }
> > return FALSE;
> > }
>
> This is a bit tricky :) You have to note that textLabel and
> textWindow both point to a string that is internal to the
> GtkLabel/GtkWindow widgets.
Right,this is the key.I forgot the memory which wouldn't be used no
longer would be freed by its widget.
> This is why the string has to the const,
> you are not allowed to modify that internal string directly. The
> point is that when you set another title or text, this internal string
> will be replaced with the new string. So as soon as you call
> gtk_window_set_title(), the internal title string will be replaced and
> after this call your textWindow pointer is no longer valid (because it
> points to this internal string that has been replaced). But you still
> have to use it for the call to gtk_label_set_text(). Swapping the
> calls will not help, because gtk_label_set_text() does the same and
> textLabel will become invalid.
>
> The easiest solution is probably to just duplicate the strings you get
> from gtk_label_get_text() and gtk_window_get_title() using g_strdup()
> (and free them at the end of the function with g_free() !). This way
> you will have a copy that will persist when the set_title() and
> set_text() functions replace their internal strings.
>
> Hope this helps.
>
>
> regards,
>
> -kris.
>
Thanks so much!
Best regards,
Randy
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