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 $_;
    }    
}

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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>

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Any advice would be much appreciated. Thanks

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.

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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

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(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--
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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.
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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.

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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>){
...
}

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    ?

    If God had meant us to fly, he would *never* have give us the railroads.
        --Michael Flanders

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