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From: steved@sun.UUCP
Newsgroups: comp.lang.fortran
Subject: Re: Problem with substrings
Message-ID: <20281@sun.uucp>
Date: Wed, 3-Jun-87 14:33:29 EDT
Article-I.D.: sun.20281
Posted: Wed Jun  3 14:33:29 1987
Date-Received: Sat, 6-Jun-87 03:46:32 EDT
References: <286@nikhefh.UUCP>
Reply-To: steved@sun.UUCP (Steve Dever)
Distribution: world
Organization: Sun Microsystems, Mountain View
Lines: 35

In article <286@nikhefh.UUCP> i91@nikhefh.UUCP (Fons Rademakers) writes:
>Does somebody know what according to the FORTRAN 77 standard 
>should happen in the following substring expression:
>
>        CHARACTER*10 CH, STR
>        
>	STR = 'ABCDEFGHIJ'
>        I   = 6
>        NC  = 0
>        CH  = 'FOO'//STR(I:I+NC-1)//'BAR'
>


The results of this program fragment are undefined.  The FORTRAN 77
standard states (section 5.7.1) that in a substring reference of the
form:

    V ( e1 : e2)

"The values of e1 and e2 *must* be such that:

      1 <= e1 <= e2 <= len

where len is the length of the character variable or array element"

So a program with a substring like this is does not conform to the
standard.  The standard does not prohibit a FORTRAN implementation
from accepting this as an extension nor does it require that it
signals an error either. 

-- 
---------------------------
Steve Dever          steved@Sun.COM
                          or
Sun Microsystems     sun!steved