Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!uunet!mcsun!ukc!cam-cl!news
From: nmm@cl.cam.ac.uk (Nick Maclaren)
Newsgroups: comp.windows.x.motif
Subject: Re: writing Widgets with Float resources
Message-ID: <1991May31.133337.7434@cl.cam.ac.uk>
Date: 31 May 91 13:33:37 GMT
References: <13743@dog.ee.lbl.gov> <910530224357.250@sony>
Reply-To: nmm@cl.cam.ac.uk (Nick Maclaren)
Distribution: inet
Organization: U of Cambridge Comp Lab, UK
Lines: 23

In article <910530224357.250@sony> nazgul@alfalfa.com (Kee Hinckley) writes:
>> It appears that no matter what I try, XtSetValues passes junk
>> as the float;  as soon as I get into my SetValues function and
>> take a look at what is passed, I get some bizarre value.  This
>Look at the structure.  sizeof(float) is probably greater than
>sizeof(long).  You'll need to use pointers to float or some such.

This may be the reason, though I rather doubt it.  I suspect that you
have been caught by a combination of the 'designs' of C and X.

If XtArgVal is char *, you are in uncharted waters.  Let us assume that
it is long (which it often is).  You are then going to end up with a
coercion from float to long, which converts the value numerically.  If
you try to avoid this by casting it to void * or char *, you are back
in uncharted waters!

I advise trying XtVaSetValues - this is at least POSSIBLE to implement
in ANSI C.  However, be warned about automatic conversion to double
in argument lists - there are some horrible traps in some compilers.

Nick Maclaren
University of Cambridge Computer Laboratory
nmm@cl.cam.ac.uk