Date: Fri, 6 Aug 2004 16:53:24 -0400
Reply-To: Quentin McMullen <mcmullen@ALEXANDER.STAT.BROWN.EDU>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Quentin McMullen <mcmullen@ALEXANDER.STAT.BROWN.EDU>
Subject: Re: flat file modification
In-Reply-To: <446DDE75CFC7E1438061462F85557B0F0458BD67@remail2.westat.com>
Content-Type: text/plain; charset="us-ascii"
Thanks Mike,
So you're suggesting that I'm not supposed to be a SAS programmer, I'm
supposed to be a programmer who uses SAS, right? I can't forget about all
them bits and bytes? I suppose had I stayed at SAS Mecca, by now I would
have taken that C class Sig suggested I take, just to learn some perspective
on/ understanding of my SAS code....
Your explanation makes sense, and matches with what a colleague told me.
That said, I got an off-list suggestion of from Randy Rak
[rrak_at_ilexonc.com], kind enough to steer me toward:
infile "c:\junk1.txt" recfm=f lrecl=100;
file "c:\junk1.txt" recfm=f lrecl=100;
Which seems to do what I want in Windows world (I do get an extra line at
the end...).
I'm still not close enough to being a real programmer to have a solid
understanding of how this is doing the memory magic (I've got some theories)
but Friday at 4:30pm before a week's vacation, it's good enough for me. : )
For those curious, I am doing this in order to post-process some RTF code
produced by ODS.
Thanks to all,
--Quentin
--------------------------------
Quentin McMullen
Center for Statistical Sciences
Brown University, Box G-H
167 Angell Street, 3rd floor
Providence, RI 02912
voice: 401-863-1164
fax: 401-863-9182
e-mail: mcmullen@stat.brown.edu
--------------------------------
> -----Original Message-----
> From: Mike Rhoads [mailto:RHOADSM1@WESTAT.com]
> Sent: Friday, August 06, 2004 3:10 PM
> To: 'Quentin McMullen'; SAS-L@LISTSERV.UGA.EDU
> Subject: RE: flat file modification
>
>
> Quentin,
>
> I always hate to say "You can't do that" on this list,
> because there are many sharp folks who can typically find
> several ways that you CAN. ;-)
>
> However, let me be brave here and say "You can't do that",
> where "that" is defined as "modifying a flat file in place by
> inserting text without losing anything."
>
> The file is just a series of bytes on the disk, which special
> bytes to determine where each "record" ends and where the
> useful data for the entire file ends. So, under Windows
> where 2 bytes (carriage-return and line-feed) separate each
> record, you would start out with:
>
> I am the first test record~^I am the second test record~^I am
> the third record~^\
>
> where I'm using ~ to represent CR, ^ to represent LF, and \
> to represent the "control Z" end-of-file character. (Not
> sure whether you'd have all 3 at EOF, or just the \.)
>
> Inserting characters would have to shift everything else in
> the file down by the number of inserted characters, which is
> not really a modification in place -- everything following
> the insertion in the file has to change/move. It's like SAS
> or some other text editor or word processor in overtype mode.
> Or think of it as being like one of those CD holders with
> slots, where you have put all your CDs alphabetically, one
> per slot, with no empty slots. If you go out and buy 2 more
> Springsteen CDs, to put them in the right place you would
> either have to move all of the CDs later in the alphabet down
> 2 slots, or take out the 2 CDs where the new ones would go
> and just toss them on the couch.
>
> That's the best explanation I can come up with on a Friday
> afternoon -- hope it helps some.
>
> Mike Rhoads
> Westat
> RhoadsM1@Westat.com
>
> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On
> Behalf Of Quentin McMullen
> Sent: Friday, August 06, 2004 2:00 PM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: flat file modification
>
>
> Thanks boss,
>
> But I think I wasn't clear.
>
> In this case I do want to insert some text into the middle of
> a line in the flat file. So I want that line to become
> longer, and I'm happy with line
> #1:
>
> > I am the best first test record
>
> But I'm not happy with the line after that, which is lacking "I am":
>
> > the second test record
>
> Your suggestion changes from a text insertion problem to a
> text replacement problem (largely my fault for providing a
> poor example).
>
> Kind Regards,
> --Quentin
>
>
>
> > -----Original Message-----
> > From: Sigurd Hermansen [mailto:HERMANS1@WESTAT.com]
> > Sent: Friday, August 06, 2004 1:48 PM
> > To: 'Quentin McMullen'; SAS-L@LISTSERV.UGA.EDU
> > Subject: RE: flat file modification
> >
> >
> > Quentin:
> > _infile_=substr(_infile_,1,9)||'best '||substr(_infile_,10+5);
> > -----
> > ^ offset by
> > length of insert.
> > Once you concatenate a string of length 5 in the line, the pointer
> > argument in the next substr() function points to the 10th (in this
> > case) character in the augmented string. The offset advances the
> > pointer beyond the insert to the string that follows the
> insert. Sig
> > -----Original Message-----
> > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On
> Behalf Of
> > Quentin McMullen
> > Sent: Friday, August 06, 2004 1:19 PM
> > To: SAS-L@LISTSERV.UGA.EDU
> > Subject: flat file modification
> >
> >
> > Hi All,
> >
> > I am attempting to modify a single line of a flat file by inserting
> > some text into the middle of it. Below, I insert some text
> into line
> > #1 of a file (modifying the file in-place). To my horror,
> line 2 is
> > modified as well. It looks like when I add 5 characters to
> line #1,
> > somehow something wraps (?) and the first 5 characters from line #2
> > are deleted. Anyway, I've tried my usual flat-file random
> > guesses (lrecl? pad? truncover?) and some new to me
> > (sharebuffers), with no joy.
> >
> > No doubt the problem is obvious to a flatfile maven out there?
> >
> > data _null_;
> > file "c:\junk1.txt";
> > put "I am the first test record";
> > put "I am the second test record";
> > put "I am the third record";
> > run;
> >
> > data _null_;
> > infile "c:\junk1.txt" ;
> > file "c:\junk1.txt" ; *modify in place (real problem is a
> > big file,
> > modifying one line);
> > input;
> > if index(_infile_,"the first") then do;
> > _infile_=substr(_infile_,1,9)||'best '||substr(_infile_,10);
> > put _infile_;
> > end;
> > stop;
> > run;
> >
> > data _null_;
> > infile "c:\junk1.txt";
> > input;
> > put _infile_;
> > run;
> >
> > Result:
> > I am the best first test record
> > the second test record
> > I am the third record
> >
> > Kind Regards,
> > --Quentin
> >
>
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