Re: File modification

A number of suggestions, actually...

You should use "strict" and "warnings".
You should use the 3-arg form of open.
You should check for failure conditions, such as open failing, or @ARGV not being set.
If you use the module FileHandle, your filehandles don't have to be typeglobs.
It is redundant to do ($_ =~ /.../); instead just do (/.../).
If you use regex captures, you don't have to split afterwards.
You're not using $changeflag; get rid of it.
Finally, you're writing every line to the file, so why not just do a regex substitution and, if it fails, write the line anyway?
It's considered good form (though not technically necessary in this case) to close your files when you're done with them.

Here's my rewrite:

#!/usr/bin/perl -w

use strict;
use warnings;

use FileHandle;

(my $argact = shift) or die "Syntax:  $0  <fileid>\n";
my $input   = new FileHandle;
my $newfile = new FileHandle;

open($input,   "<", "one.txt") or die "Failed to read 'one.txt' ($!)\n
+";
open($newfile, ">", "output")  or die "Failed to write 'output' ($!)\n
+";

while(<$input>){
    s/^Authentication\s+number\s+is\s+(\d+)/Authentication number is $
+argact/;
    print $newfile "$_";
}

close $input;
close $newfile;
[download]

Isn't that a lot cleaner?

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

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Re^2: File modification by roboticus (Chancellor) on Jul 07, 2006 at 12:51 UTC
liverpole: ++ Excellent suggestions! One trivial note, though: Your blank lines appear to be a long string of blanks, as there are many unexpected line continuation characters on the screen here. (I just did a view source: The code lines don't appear to have trailing blanks, but all the blank lines do. I don't know if it's an artifact of how you pasted the code in, but I thought I'd mention it.) --roboticus	[reply]
Re^3: File modification by liverpole (Monsignor) on Jul 07, 2006 at 13:05 UTC
Thanks, roboticus, for your kind comments, and the feedback about the "long lines". I've fixed them. Yes you're right, it is an artifact of cut-and-paste. I've seen it before, and usually just fix it by hand, though it can be tedious if it's a long program. I don't know if it's the browser I'm using (Firefox), or if there's some easier way to fix it, but I'd be glad to hear of anyone else who's found a simpler solution. s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/	[reply]
Re^3: File modification by shmem (Chancellor) on Jul 07, 2006 at 18:38 UTC
++liverpole, just to be pedantic... ;-) check the return value of `close FH` (think NFS; file system full?) --shmem oops, this leaf wrong twig :-P _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l]