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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!sun-barr!newstop!sun!road!khb
From: khb@road.Sun.COM (Keith Bierman - Advanced Languages - Floating Point Group )
Newsgroups: comp.lang.fortran,comp.os.vms
Subject: Re: Question about variables local to subroutine
Keywords: Local variables, subroutines
Message-ID: <123145@sun.Eng.Sun.COM>
Date: 23 Aug 89 07:10:15 GMT
References: <24891@iuvax.cs.indiana.edu>
Sender: news@sun.Eng.Sun.COM
Reply-To: khb@sun.UUCP (Keith Bierman - Advanced Languages - Floating Point Group )
Organization: Sun Microsystems, Mountain View
Lines: 42

In article <24891@iuvax.cs.indiana.edu> templon@silver.bacs.indiana.edu (jeffrey templon) writes:
>
>I would like to know one simple (I hope) thing: what happens if you set
>the value of a variable (local) in a subroutine, exit the subroutine, and
>come back later?  Is it the same value, zero, or worse?  I read all TFMs
>I could find and saw no answer to this one.  I am using VAX Fortran,
>whatever version runs on VMS V4.6.  Thanks for any help you can send.
>
>					Jeff Templon


Well, if you read the standards document (:> turgid prose at best),
you will find that if you declare your variable

	subroutine sub(stuff)

	real your_var  ! extended fortran, for long var name and underscore
	save your_var  ! not to mention lower case and !

the standard assures you that your_var has the result from the last
invocation. 

If you don't employ save, vendor gets to do whatever they want.

DEC VMS FORTRAN happens to make all variables SAVEd for you anyway.

UNIVAC (used to) gives you junk. Sun (well me) strongly advises use of
the SAVE, if you really want your old value back.

I know of no one who promises you zero ... many machines (dec, sun)
give you zero the first time through ... second time zero is about the
least likely number.

-- 
Keith H. Bierman    |*My thoughts are my own. !! kbierman@sun.com
It's Not My Fault   |	MTS --Only my work belongs to Sun* 
I Voted for Bill &  | Advanced Languages/Floating Point Group            
Opus                | "When the going gets Weird .. the Weird turn PRO"
Keith H. Bierman    |*My thoughts are my own. !! kbierman@sun.com
It's Not My Fault   |	MTS --Only my work belongs to Sun* 
I Voted for Bill &  | Advanced Languages/Floating Point Group            
Opus                | "When the going gets Weird .. the Weird turn PRO"