Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!ysub!fc138001
Organization: Youngstown State University VM system (YSUB)
Date: Saturday, 8 Jun 1991 12:11:42 EDT
From: Phil Munro <FC138001@ysub.ysu.edu>
Message-ID: <91159.121142FC138001@ysub.ysu.edu>
Newsgroups: comp.lang.fortran
Subject: More on EQUIVALENCE (and CHARACTER)
Distribution: na
References: <1991Jun1.171914.802@weyrich.UUCP>
 <1991Jun5.220805.4653@alchemy.chem.utoronto.ca>
 <1991Jun7.022834.898@weyrich.UUCP>
 <1991Jun7.144220.16691@alchemy.chem.utoronto.ca>

>     ...                                               It has struck me
>since however that since the standard doesn't say what to do when one
>equivalences across data types, a particularly odd compiler could
>transform the "obvious" meaning of EQUIVALENCE into something else
>entirely (and still conform to the standard).  (I believe that this
>situation is common when equivalencing any numerical type to CHARACTER
>because of the peculiar way in which character variables are stored in
>some systems.)  I therefore retract my example.  I don't think you can use
>equivalence portably to do anything other than save space.
>
>                                Marc R. Roussel
>                                mroussel@alchemy.chem.utoronto.ca

  The above discussion raises questions for me.  Will the following code
be portable?  Might it cause problems on some compilers when trying to
pick off part of whole and overlay storage?  I know in the case of the
VS compiler that character storage allows this sort of thing.

      character*14 whole
      character*4  part
      data whole /'part and so on'/
      equivalence (whole,part)

  Or, here is another simpler example which I have used:

      character*8 blank8
      character*4 blank
      equivalence (blank8,blank)
      data blank8 /' '/