Search/Replace Character

rhiannasilel has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to do a replace by character on positions 12 and 13 of a flat file. These positions consistently are populated with "DC" and need to be replaces with two spaces. I don't want to do a global search and replace because there could be DC's elsewhere in the file that should not be replaced. My script is removing the DC's correctly; however, I appear to be losing 10 spaces in the new flat file as a result. This file is going to be used to upload into a database so the character positioning is vital. Any advice on where I'm going wrong? Here's my script:

#!/usr/bin/perl

$upload="<upload dir>";
$output="<output dir>";
$inputFile="$upload/inputFile.txt";

$filename="$upload/file.txt.mrk";
$outFile="$output/test.tmp";

open(MYINPUTFILE, "<$filename"); # open for input
open(MYOUTPUTFILE, ">>$outFile");
my(@lines) = <MYINPUTFILE>;
my($line);
 foreach $line (@lines)
 {
 print $line;
 substr($line,11,13)="  ";
 print MYOUTPUTFILE "$line";
 }
close(MYINPUTFILE);
close(MYOUTPUTFILE);
[download]

Comment on Search/Replace Character Download Code

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Re: Search/Replace Character by FunkyMonk (Bishop) on Apr 17, 2008 at 15:18 UTC
The 3rd argument of substr is a length, not another offset! You should be using `substr($line,11,2)=" ";` Unless I state otherwise, my code all runs with strict and warnings	[reply] [d/l] [select]
Re^2: Search/Replace Character by rhiannasilel (Initiate) on Apr 17, 2008 at 18:52 UTC
Aha! Thank you so much. So it's the same logic as it would be with awk, then? Got it. It's working perfectly now.	[reply]
Re: Search/Replace Character by elmex (Friar) on Apr 17, 2008 at 15:43 UTC
As already said, the third paramenter to `substr` is the length of the addressed substring. But for the sake of diversity, here a regex that would work: `# ... for my $line (@lines) { print $line; $line =~ s/^(.{11})DC/\1 /; print MYOUTPUTFILE $line; } # ...` [download] And if your script is just for filtering text files you could even reduce the whole thing to a simple command line (if you have a shell, that is): `elmex@home: ~# cat file.txt.mrk \| perl -ne 's/^(.{11})DC/\1 /; pri +nt' >> test.tmp` [download]	[reply] [d/l] [select]
Re^2: Search/Replace Character by moritz (Cardinal) on Apr 17, 2008 at 15:46 UTC
If you had warnings in effect, you'd get this message: `\1 better written as $1` [download]	[reply] [d/l]
Re^2: Search/Replace Character by rhiannasilel (Initiate) on Apr 17, 2008 at 18:59 UTC
Thanks for the suggestions. The command line idea will come in really handy. I get a lot of one off text files from my users where a vendor put in a wrong code or put a code in the wrong position and we need to adjust it. This can be a real pain when the file is over 1,000 records or more in some cases.	[reply]