special variable?

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

The code adds the delimiter to the file between all parameters but to remove and display it on the browser is another story cant do it making a silly mistake somewhere

#!/usr/bin/perl -w

use strict;
use warnings;
use CGI;
use CGI::Carp qw(fatalsToBrowser);

my $query= new CGI;
my $filename= "testfile.txt";
my $value;
my $fname;
my $lname;
my $textarea;
      $'="|";
sub Writing_to_file
    {

            my @input_to_file=@_; 
            open (DAT, ">>$filename") || die ("no file exists");
            print DAT join($', @input_to_file), "\n";
            close(DAT);
    }

sub display_on_browser
        {
            open (DAT, $filename) || die ("no file exists");
            my @data_in_the_file=<DAT>;
            close(DAT);
            my $data_to_read;
            print "Content-type:text/html\n\n";
            print"<html><head><title>Guestbook</title></head><body>";
            foreach $data_to_read(@data_in_the_file)
            {
                my @delimiter_to_remove=$data_to_read;
                @delimiter_to_remove=~s/\$'/\n/g;
                print "<table border=1><tr><td>@delimiter_to_remove\n<
+br></td></tr></table>";
            }
                print "<a href=http://guestbook.ds5403.dedicated.turbo
+dns.co.uk/index.html><h1>Back to guestbook</a>";
                print "</body></html>";
        }
$fname=$query->param('name');
$lname=$query->param('name1');
$textarea=$query->param('comments');
Writing_to_file($fname,$lname,$textarea);
display_on_browser();
[download]

Please advise thanks jinnks

Comment on special variable? Download Code

Replies are listed 'Best First'.
Re: Special variable... by Lawliet (Curate) on Aug 06, 2008 at 02:00 UTC
As mentioned in the CB, `$' is the same as substr($var, $+[0])` The reason you have to use `@-` is $' is a read only variable. (Also, it is a memory hog) `<(^.^-<) <(-^.^<) <(-^.^-)> (>^.^-)> (>-^.^)>`	[reply] [d/l] [select]
Re: Special variable... by kyle (Abbot) on Aug 06, 2008 at 02:30 UTC
Welcome to the Monastery! I think instead of `$'` (which is read-only), you want `$"`, which is what gets put between list elements interpolated into a double quoted string. As an aside, I'd suggest that this: `open (DAT, ">>$filename") \|\| die ("no file exists");` [download] ...be more like this: `open my $dat, '>>', $filename or die "Can't append '$filename': $!";` [download] That way you get a better error message, and it won't matter if `$filename` starts with some strange characters. I'm opening a lexical scalar as a filehandle here too, so you'd use "`$dat`" everywhere you had "`DAT`" before. Updated to add that I also agree with toolic that using a special variable here is not really necessary.	[reply] [d/l] [select]
Re: Special variable... by toolic (Bishop) on Aug 06, 2008 at 02:29 UTC
Lawliet has correctly diagnosed your problem: that you should not assign to the `$'` special variable (see perlvar). However, I do not understand why you are trying to use that variable at all in your code. If you are trying to join and split using "\|" as a delimiter, you can just do: `print DAT join('\|', @input_to_file), "\n"; @data_to_print=split /\\|/, $data_to_read;` [download]	[reply] [d/l] [select]