Re: fortran/4885: BACKSPACE example that doesn't work as of gcc/g77-3.0.x

[Toon Moene <toon@moene.indiv.nluug.nl>]

The following reply was made to PR fortran/4885; it has been noted by GNATS.

From: Toon Moene <toon@moene.indiv.nluug.nl>
To: Youngjean Jung <yjjung@newton.me.berkeley.edu>
Cc: Tim Prince <tprince@computer.org>, gcc-gnats@gcc.gnu.org
Subject: Re: fortran/4885: BACKSPACE example that doesn't work as of 
 gcc/g77-3.0.x
Date: Fri, 16 Nov 2001 21:31:41 +0100

 Youngjean Jung wrote:
 
 > I conducted many tests on the Endfile, Backspace commands. They don't
 > work in the following senses:
 > 
 > 1) Endfile command writes meaningless letters on the data file.
 > 2) Endfile, Backspace combination doesn't make a 'backspace job'.
 
 >       program test
 > c
 >       implicit none
 >       integer  i,k
 > c
 >       do i=1,10
 >         open(1,file='s2.dat',status='unknown',access='sequential')
 >         do k=10,20
 >            write(1,*) i,k
 >            endfile 1
 >            backspace 1
 >         end do
 >         close(1)
 >       end do
 > c
 >       end
 
 Hmmm, I get the same s2.dat as you get (Debian GNU/Linux 2.2,
 gcc/g77-3.0.2):
 
 toon@laptop:~/g77-bugs$ cat s2.dat
  10 10
  10 11
  10 12
  10 13
  10 14
  10 15
  10 16
  10 17
  10 18
  10 19
  10 20
 
 This seems to be in accordance with the Standard:
 
 12.10.4.1 BACKSPACE Statement.
 
 Execution of a BACKSPACE statement causes the file connected to the
 specified unit to be positioned before the preceding record. If there is
 no preceding record, the position of the file is not changed. Note that
 if the preceding record is an endfile record, the file becomes
 positioned before the endfile record. 
 
 In other words, your backspace only backspaces over the endfile record
 (as per the standard).  If you want to backspace over the record you
 just wrote, you have to backspace twice.
 
 [Tim - does this mean I can close fortran/4885 ?  Thanks]
 
 -- 
 Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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