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From: argv@turnpike.Eng.Sun.COM (Dan Heller)
Newsgroups: comp.windows.x.motif
Subject: Re: trouble with structures and callbacks
Message-ID: <3340@exodus.Eng.Sun.COM>
Date: 23 Nov 90 19:33:50 GMT
References: <2450@kiwi.mpr.ca>
Sender: news@exodus.Eng.Sun.COM
Organization: O'Reilly && Associates
Lines: 36

In article <2450@kiwi.mpr.ca> baker@mprgate.mpr.ca (Sue Baker) writes:
> i'm trying to pass a structure as client_data to a callback function,
> and am achieving nothing but frustration.

That's because you're passing a whole structure rather than a
pointer to one.

>     struct widget_type{               /* more detail to be added */
>         Widget widget_array[4]; };    /* to structure later */
>     struct widget_type text;
>     XtAddCallback(update, XmNactivateCallback, get_text, text);

The arg "text" should be "&text".  e.g.:
      XtAddCallback(update, XmNactivateCallback, get_text, &text);

void
get_text(widget, text_data, cbs)
Widget widget;
widget_type *text_data;
XmAnyCallbackStruct *cbs;
{
    int i;
    char *p;

    /* print the text of the widget in array */
    for (i = 0; i < 4; i++) {
	p = XmTextGetString(text_data->widget_array[i]);
	printf("widget_array[%d] = %s\n", i, p);
	XtFree(p);
    }
}
--
dan
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