Help with warnings!!!

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

Hello all, i am in desperate need of help to get rid of certain warnings, i tryied taking away the warnings, and strict stubs but no go!!!!!
here is my code

#!/usr/bin/perl
  use strict;
  use warnings;
my $program = 'netstat -a';
my @lines;
my ($protocol, $localAddress, $foreignAddress, $state);

  open NETSTAT, "$program|" or die "Cannot open netstat $!\n";
  @lines = <NETSTAT>;
  close NETSTAT;

foreach (@lines) {
  /(\w+)\s+(\w+:\w+)\s+(\d+\.\d+\.\d+\.\d+):\w+\s+(\w+)/;
  if($1, $2, $3, $4) {
    $protocol = $1;
    $localAddress = $2;
    $foreignAddress = $3;
    $state = $4;
    print "$protocol, $localAddress, $foreignAddress, $state\n";
  }
}
[download]

------------ end code -------------
results
-----------------------------------

  Useless use of a variable in void context at netstatReader.pl line 2
+6.
  Useless use of a variable in void context at netstatReader.pl line 2
+6.
[download]

20030818 Edit by Corion: Fixed formatting

Comment on Help with warnings!!! Select or Download Code

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Re: Help with warnings!!! by liz (Monsignor) on Aug 18, 2003 at 20:02 UTC
What do you think you're accomplishing with: `if($1, $2, $3, $4) {` [download] ? I think you probably mean either: `if($1 or $2 or $3 or $4) { # any of $1..$4 is not empty` [download] or: `if($1 and $2 and $3 and $4) { # all of $1..$4 are not empty` [download] Liz	[reply] [d/l] [select]
Re: Help with warnings!!! by Thelonius (Priest) on Aug 18, 2003 at 20:25 UTC
You actually want: `foreach (@lines) { if(/(\w+)\s+(\w+:\w+)\s+(\d+\.\d+\.\d+\.\d+):\w+\s+(\w+)/) { $protocol = $1; $localAddress = $2; $foreignAddress = $3; $state = $4; print "$protocol, $localAddress, $foreignAddress, $state\n"; } }` [download] This is because if a line fails to match, perl will not reset $1, $2, $3, $4, so they will still have a value from the previous match. Also, if you are not going to use the @lines array for something else, it's much more memory-efficient to combine the loops like this: `open NETSTAT, "$program\|" or die "Cannot open netstat $!\n"; while (<NETSTAT>) { if(/(\w+)\s+(\w+:\w+)\s+(\d+\.\d+\.\d+\.\d+):\w+\s+(\w+)/) { print "$1, $2, $3, $4\n"; # protocol, localAddress, foreignAddress, state } }` [download]	[reply] [d/l] [select]
Re: Help with warnings!!! by dragonchild (Archbishop) on Aug 18, 2003 at 20:02 UTC
`if($1, $2, $3, $4) ----- if ($1 && $2 && $3 && $4)` [download] Make that change and it'll be fine. You weren't doing what you thought you were doing. :-) ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply] [d/l]
Re: Help with warnings!!! by tcf22 (Priest) on Aug 18, 2003 at 20:04 UTC
Change `if($1, $2, $3, $4)` [download] to `if($1 && $2 && $3 && $4)` [download] Update: I guess liz and dragonchild beat me to it.	[reply] [d/l] [select]
Re: Re: Help with warnings!!! by jmaya (Acolyte) on Aug 18, 2003 at 20:14 UTC
Yup!!! thank you guys.... Newbie stuff. slowly but sureley...	[reply]