Path: utzoo!attcan!telly!druid!darcy
From: darcy@druid.uucp (D'Arcy J.M. Cain)
Newsgroups: comp.lang.c
Subject: Re: append mode "a" query
Message-ID: <1990Feb16.180007.1166@druid.uucp>
Date: 16 Feb 90 18:00:07 GMT
References: <5003.25dabd8f@uwovax.uwo.ca>
Reply-To: darcy@druid.UUCP (D'Arcy J.M. Cain)
Organization: D'Arcy Cain Consulting, West Hill, Ontario
Lines: 42

In article <5003.25dabd8f@uwovax.uwo.ca> chet@uwovax.uwo.ca writes:
>
>(2) The EOF (^Z, dec 26) was introduced by an assembly language editor
>that I sometimes use. When I used only MicroEMACS, program B ran
>without problem on Turbo C and Small-C. Whenever I used the other
>editor, the ^Z crept in (I used a third, binary, editor to confirm
>these facts).
>
>(3) For Turbo C, a simple fix was to change the mode from "a" (which by
>default is "at") to "r+" and then use lseek(fp, -1, 2). This position
>the file pointer just before the EOF. Note, however, that it should not
>be necessary to do this!
>
Why not?  If you have an editor that thinks it is running on CP/M and must
add a ^Z to the end of the file then why wouldn't an append happen after
the last character in a file.  Do you think there is something special
about ^Z that DOS or fopen should recognize?  After all ^Z doesn't even
make any sense as an end of file.  It is a SUB (substitute) character
in ASCII.  I would think the following would make at least as much sense
as an end of file marker if one was needed:

^C  ETX  End of text
^D  EOT  End of transmission
^W  ETB  End of transmission block
^Y  EM   End of medium
^\  FS   File separator

So why not have append append from the ^D for instance.  Nope.  The
proper thing for append to do is go to the end of the physical file
and the programmer must back up if there are characters in the file 
that don't belong there.

Maybe you should write a utility that searches for ^Z and resizes the file
to the character before it.  Then you have a standard file which append
works properly on.


-- 
D'Arcy J.M. Cain (darcy@druid)     |   Thank goodness we don't get all 
D'Arcy Cain Consulting             |   the government we pay for.
West Hill, Ontario, Canada         |
(416) 281-6094                     |