Seeing double

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

This script takes a text file and parses two types of lines; Customer name and Message-Id. Unfortunately, there are usually two Message-Id tags per email. Anybody know how I would get the script to ignore the second one? Here is the code:

#!/usr/bin/perl

$textfile = "iwn.txt";

open (TEXT, "$textfile") || die "Con't Open $textfile";


@text=<TEXT>;
close(TEXT);
$glob = @text;

for($i=0; $i<$glob; $i++){
    $_ = @text[$i];
    if(/Email address:/){

        print $_;
    }
    elsif(/Message-Id:/){
        print $_;
    }    
}
[download]

Here are the current results with two emails:

Email address:     19324213@glerp  
Message-Id: <200103160515.WAA07878@mal.elp.rr.com>
Message-Id: <200103160515.WAA07878@mal.elp.rr.com>
Email address:     19075680@glerp
Message-Id: <200103150512.VAA27508@prxy3.ba.best.com>
Message-Id: <200103150512.VAA27508@prxy3.ba.best.com>
[download]

Any advice would be much appreciated. Thanks

Comment on Seeing double Select or Download Code

Replies are listed 'Best First'.
(Ovid - remove duplicates) Re: Seeing double by Ovid (Cardinal) on Apr 20, 2001 at 01:53 UTC
My thought: use a hash. `#!/usr/bin/perl -w use strict; my %message_id; while ( <DATA> ) { if ( /Email address:/ ) { print; } elsif ( /Message-Id:/ && ! $message_id{ $_ }++ ) { print; } } __DATA__ Email address: 19324213@glerp Message-Id: <200103160515.WAA07878@mal.elp.rr.com> Message-Id: <200103160515.WAA07878@mal.elp.rr.com> Email address: 19075680@glerp Message-Id: <200103150512.VAA27508@prxy3.ba.best.com> Message-Id: <200103150512.VAA27508@prxy3.ba.best.com>` [download] Cheers, Ovid Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l]
Re: Seeing double by stephen (Priest) on Apr 20, 2001 at 01:58 UTC
If what you're parsing is a file full of e-mails, I'd recommend going straight for the Mail-Tools. Mail::Util will break up a file full of mail messages into individual messages. Mail::Internet can be used to parse out those messages, and Mail::Header can be used to parse that header. Once you're dealing with headers individually, your problem becomes much simpler. stephen	[reply]
Re: Seeing double by indigo (Scribe) on Apr 20, 2001 at 01:35 UTC
Sure. `#!/usr/bin/perl -w use strict;` [download] Always use -w and use strict. `my $textfile = "iwn.txt";` Use my to declare variables under use strict. `open TEXT, $textfile or die "Can't Open $textfile"; my ($email, $id); while (<TEXT>){ $email \|\|= $_ if /Email address:/; $id \|\|= $_ if /Message-Id:/; }` [download] You were using C style looping. Perl loops are much nicer. $x \|\|= $y (or equals) is the same as $x = $x \|\| $y. The end effect for you is $id gets a value only if it doesn't already have one. `close TEXT; print $email; print $id;` [download] Pulling these variables out of the loop ensures they only get printed once.	[reply] [d/l] [select]
(jeffa) Re: Seeing double by jeffa (Bishop) on Apr 20, 2001 at 01:26 UTC
Here is one way, with a cheesy flag: `use strict; my $textfile = "iwn.txt"; open (TEXT, "$textfile") \|\| die "Con't Open $textfile"; my @text=<TEXT>; close(TEXT); my $flag = 0; foreach (@text) { if (/Email address:/) { print; $flag = 0; } if (/Message-Id:/ and !$flag) { print; $flag = 1; } }` [download] Jeff R-R-R--R-R-R--R-R-R--R-R-R--R-R-R-- L-L--L-L--L-L--L-L--L-L--L-L--L-L--	[reply] [d/l]
Re: Seeing double by satchboost (Scribe) on Apr 20, 2001 at 01:26 UTC
Use a counter. So, you'd have something like: `elsif (/Message-Id:/) { $counter = 1 - $counter; print $_ if $counter; }` [download] Somewhere in the beginning, have `my $counter = 0;` and you should be fine.	[reply] [d/l] [select]
Re: Seeing double by ChemBoy (Priest) on Apr 20, 2001 at 01:33 UTC
Couple of quick ideas: `my $flag=0; for($i=0; $i<$glob; $i++){ $_ = @text[$i]; if(/Email address:/){ print $_; } elsif(/Message-Id:/ and !$flag++){ print $_; } }` [download] Or alternatively `my ($email,$mesgid)= ("",""); for($i=0; $i<$glob; $i++){ $_ = @text[$i]; if(/Email address:/){ $email = $_; } elsif(/Message-Id:/){ $mesgid = $_; } } print $email,$mesgid;` [download] And a question: why the for loop, instead of `while (<TEXT>){ ... }` [download] ? If God had meant us to fly, he would never have give us the railroads. --Michael Flanders	[reply] [d/l] [select]


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