Path: utzoo!attcan!uunet!wuarchive!uwm.edu!ux1.cso.uiuc.edu!hirchert
From: hirchert@ux1.cso.uiuc.edu (Kurt Hirchert)
Newsgroups: comp.lang.fortran
Subject: Re: COMMON and SAVE statements
Message-ID: <1990Aug7.141214.20334@ux1.cso.uiuc.edu>
Date: 7 Aug 90 14:12:14 GMT
References: <65861@lll-winken.LLNL.GOV> <1990Aug6.215727.21612@ux1.cso.uiuc.edu> <6814@vax1.acs.udel.EDU>
Organization: National Center for Supercomputing Applications
Lines: 22

In article <6814@vax1.acs.udel.EDU> gilmore@vax1.udel.edu (Scott Gilmore) writes:
>In article <1990Aug6.215727.21612@ux1.cso.uiuc.edu> hirchert@ux1.cso.uiuc.edu (Kurt Hirchert) writes:
>>Also, as someone else pointed out, if you declare your COMMON block in your
>>main program, you don't need to SAVE them explicitly. 
>
>What about BLOCK DATA subprograms?  Does this implicit save behavior also 
>apply to them?
>-- 
>Scott Gilmore                                       gilmore@vax1.udel.edu
>Mechanical Engineering and Center for Composite Materials, U. of Delaware

No.  If a variable or array in a COMMON block is initialized (through a BLOCK
DATA) and not subsequently redefined, it will remain defined even if not SAVEd,
but that's all.  In other words, if you are using a value in COMMON as a kind
of global constant, it will work, but the mere fact that you initialize a
COMMON block is not enough in general to make it retain values between CALLs.
(In the overlay model, this means that an unSAVEd COMMON can still be moved
out to a branch overlay with the initialization of that COMMON being done
each time the overlay is loaded.)
-- 
Kurt W. Hirchert     hirchert@ncsa.uiuc.edu
National Center for Supercomputing Applications