Welcome to the Monastery, deep27ak!

At a glance, it appears as though you've got numerous issues with your code, including undefined variables, an erroneous }, repeatedly reassigning over a variable without using it in loops etc.

Please post enough of a sample of the XML file you're using as input that will satisfy a single pass of the script. Without that, it's too time consuming to reconstruct the code properly.

Also, get in the habit of using proper indenting. It'll help you greatly, and it'll help us work with what you've got.

Here's an example:

use strict;
use warnings;
use XML::Simple;

my $xml = do {local $/='';'network.xml'} ;
my $servers = XMLin($xml, ForceArray => 1);
my %seen;

foreach my $server (@{$servers->{server}}) {

    my $brlist;
    my $corebrip;
    my $brmask;
    my $brip;
    my $num;
    my $brlan;

    my @node =  $server->{NodeName__1} . "\n";
    my $lanip = $server->{CoreLanIP_1__1}  ;
    my @mask = $server->{CoreLanNetmask_1} . "\n";

    my $network = join("/", $lanip, @mask);
    $network =~ s/.[0-9]*\//.0\//g;
    push(my @networklist, $network) if ! $seen{$network}++;
    $brlan = $server->{BRLAN} ;

    if ( $brlan eq "y" )  {
        $brip = $server->{BR_IP};
        $num = $server->{CoreLanNum} ."\n" ;
    }

    my  @brnwlist;

    for my $n (1..$num){
        $corebrip = $server->{'CoreLanIP_'.$n.'__1'} ;
        $brmask  = $server->{'CoreLanNetmask_'.$n} ."\n";
    }

    if ( $corebrip eq $brip ){

        $brlist = join ("/", $brip, $brmask) ;
        $brlist =~  s/.[0-9]*\//.0\//g;
        push( @brnwlist, $brlist) unless $seen{$brlist}++;
    }
    else {
        print "coreip doesnot matches brip\n";
    }
}

for $a (@brnwlist) {

    if ( $a ne "") {
        print "empty array";

        my $vnum = $server->{CoreVlanNum} ."\n" ;

        for my $i (1..$vnum){

            my $vlanip = $server->{'CoreVlan_IP_'.$i} ;
            my $vmask  = $server->{'CoreVlan_Netmask_'.$i} ."\n";

            if ($vlanip eq $brip){

                my $vlist = join ("/", $brip, $vmask) ;
                $vlist =~  s/.[0-9]*\//.0\//g;
                push(my @vnwlist, $vlist) if ! $seen{$vlist}++;
                print @vnwlist;
            }
        }
    }
}
[download]

-stevieb

Thanks very much for looking into this. Yes I understand it has multiple issues and I am still trying to evolve on scripting so I sure WILL take your advice in upcoming posts

I have updated my question a trimmed version of xml although it contains all the necessary input required for the script.

if BRLAN = y then first the script should search for CoreLanNum $n. and the loop should run as many times as $n and should match BR_IP with CorLanNum_IP and store the value in a array.

If this array is empty run next for loop and search of CoreVlanNum $n and the script should again search for CoreVlanIP with BR_IP and map it with equivalent netmask.

For the first server mch30-nds-ins there in no BR_IP attribute to match against.

poj

use Data::Dumper;
my $count = 1;

foreach my $server (@{$servers->{server}}) {
    print "\nCount: ", $count++, "\n";
    my $brlan = $server->{BRLAN} ;
    print "brlan = $brlan\n";
    next unless $brlan eq "y";
    
    my $brip = $server->{BR_IP};
    my $num = $server->{CoreLanNum};
    my $corebrip = $server->{'CoreLanIP_'.$num.'__1'} ;
    my $brmask  = $server->{'CoreLanNetmask_'.$num};
    my @brnwlist;
    for my $n (1..$num){
        $corebrip = $server->{'CoreLanIP_'.$n.'__1'} ;
        if (not $corebrip) {
            print "CoreLanNum $n - No value for CoreLanIP_".$n."__1\n"
+;
            next;
        }
        print "CoreLanNum $n - brip: $brip, corebrip: $corebrip\n";
        $brmask  = $server->{'CoreLanNetmask_'.$n};
        if ( $corebrip eq $brip ){
            my $brlist = join ("/", $brip, $brmask) ;
            $brlist =~  s/.[0-9]*\//.0\//g;
            push( @brnwlist, $brlist) unless $seen{$brlist}++;
        }
        else {
            print "coreip does not match brip\n";
        }
    }
    print "brnwlist: ", Dumper(\@brnwlist);
    next if @brnwlist;
    
    my @vnwlist;
    my $vnum = $server->{CoreVlanNum};
    for my $i (1..$vnum){
        my $vlanip = $server->{'CoreVlan_IP_'.$i};
        if (not $vlanip) {
            print "CoreVlanNum $i - No value for CoreVlan_IP_$i\n";
            next;
        }
        print "CoreVlanNum $i - brip: $brip, vlanip: $vlanip\n";
        my $vmask  = $server->{'CoreVlan_Netmask_'.$i};
        if ($vlanip eq $brip){
            my $vlist = join ("/", $brip, $vmask) ;
            $vlist =~  s/.[0-9]*\//.0\//g;
            push(my @vnwlist, $vlist) if ! $seen{$vlist}++;
        }
        else {
            print "vlanip does not match brip\n";
        }
    }
    print "vnwlist: ", Dumper(\@vnwlist);
}
[download]

Count: 1
brlan = n

Count: 2
brlan = y
CoreLanNum 1 - brip: 192.168.165.16, corebrip: 192.168.156.16
coreip does not match brip
CoreLanNum 2 - brip: 192.168.165.16, corebrip: 192.168.156.16
coreip does not match brip
brnwlist: $VAR1 = [];
CoreVlanNum 1 - brip: 192.168.165.16, vlanip: 192.168.156.16
vlanip does not match brip
CoreVlanNum 2 - No value for CoreVlan_IP_2
vnwlist: $VAR1 = [];

Count: 3
brlan = y
CoreLanNum 1 - brip: 192.169.73.1, corebrip: 192.169.32.1
coreip does not match brip
CoreLanNum 2 - brip: 192.169.73.1, corebrip: 192.169.32.1
coreip does not match brip
CoreLanNum 3 - brip: 192.169.73.1, corebrip: 192.169.73.1
CoreLanNum 4 - brip: 192.169.73.1, corebrip: 192.169.73.1
brnwlist: $VAR1 = [
          '192.169.73.0/255.255.255.240'
        ];
[download]

Thanks very much stevieb and tangent.

You guys made my day. I now understand the usage of variables and the place it should be defined. I did tried using subroutines but I believe my script requirement would be fulfilled more by the second method.

Till now the script does works as expected with one loop hole as I see.

After picking up unique values the output contains empty lines as below

If vlannum exists

vnwlist: $VAR1 = [
          '192.168.165.0/255.255.255.0
'
        ];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
vnwlist: $VAR1 = [];
[download]

if corelannum exists

brnwlist: $VAR1 = [
          '192.169.73.0/255.255.255.0
'
        ];
brnwlist: $VAR1 = [];
brnwlist: $VAR1 = [];
brnwlist: $VAR1 = [];
brnwlist: $VAR1 = [];
brnwlist: $VAR1 = [];
[download]

I tried various provided here http://www.perlmonks.org/?node_id=124970

but nothing seems to work in my case. At one point I have to dump these values in a file and with these empty lines it will not be proper.

Also can someone please help me understand why do we use Data:Dumper ?

my script

        for my $n (1..$num){
        $corebrip = $server->{'CoreLanIP_'.$n.'__1'} ;
        if (not $corebrip) {
            print "CoreLanNum $n - No value for CoreLanIP_".$n."__1\n"
+;
        next;
        }
#       print "CoreLanNum $n - brip: $brip, corebrip: $corebrip\n";
        $brmask  = $server->{'CoreLanNetmask_'.$n} . "\n" ;
        if ( $corebrip eq $brip ){
        $brlist = join ("/", $brip, $brmask) ;
        $brlist =~  s/.[0-9]*\//.0\//g;
        push( @brnwlist, $brlist) unless $seen{$brlist}++;
        }
        else {
#       print "coreip doesnot matches brip\n";
        }
    }
        print "brnwlist: ", Dumper(\@brnwlist);

        next if @brnwlist;
        my @vnwlist;
        my $vnum = $server->{CoreVlanNum};
        for my $i (1..$vnum){

        my $vlanip = $server->{'CoreVlan_IP_'.$i} ;
        if (not $vlanip) {
#       print "CoreVlanNum $i - No value for CoreVlan_IP_$i\n";
            next;
        }
#       print "CoreVlanNum $i - brip: $brip, vlanip: $vlanip\n";
        my $vmask  = $server->{'CoreVlan_Netmask_'.$i} . "\n";

        if ($vlanip eq $brip){
        my $vlist = join ("/", $brip, $vmask) ;
        $vlist =~  s/.[0-9]*\//.0\//g;
        push @vnwlist, $vlist unless $seen{$vlist}++;

        }
     }
         @vnwlist = grep (/\S/, @vnwlist);
         print "vnwlist: ", Dumper(\@vnwlist);
  }
}
[download]

I played around for a bit and did a bunch of cleanup. I'm not sure if this does exactly what you're after, but it shows a much better structure that you should be able to follow.

The biggest thing is that I got rid of all the variable definitions near the top. It's much easier to troubleshoot when you declare your variables immediately before use where possible.

This code surely needs more work, but I did what I could with the time I had. Also note that it doesn't look like you use @networklist, but I left it in anyways.

use strict;
use warnings;
use XML::Simple;

use Data::Dumper;

my $xml = do {local $/='';'in.xml'} ;
my $servers = XMLin($xml, ForceArray => 1);
my %seen;

my @networklist;
my @brlist;
my @vlist;

for my $server (@{$servers->{server}}){

    my $node =  $server->{NodeName__1};
    my $lanip = $server->{CoreLanIP_1__1};
    my $mask = $server->{CoreLanNetmask_1};

    my $network = join("/", $lanip, $mask);
    $network =~ s/.[0-9]*\//.0\//g;

    push @networklist, $network if ! $seen{$network}++;

    if ($server->{BRLAN} eq "y" ){
        core_lan($server);
    }
    else {
        core_vlan($server);
    }
}

# output

print "\nBRNW LIST\n";
print Dumper \@brlist;

print "\nVLAN LIST\n";
print Dumper \@vlist;

exit(0);

#
# subroutine definitions
#

sub core_lan {

    my $server = shift;

    my $brip = $server->{BR_IP};
    my $num = $server->{CoreLanNum};

    for (1..$num){
        my $corebrip = $server->{'CoreLanIP_'.$_.'__1'};
        my $brmask  = $server->{'CoreLanNetmask_'.$_};

        if ($corebrip eq $brip){
            my $brlist = join ("/", $brip, $brmask);
            $brlist =~  s/.[0-9]*\//.0\//g;

            push @brlist, $brlist unless $seen{$brlist}++;
        }
        else {
            print "coreip doesnot matches brip\n";
        }
    }
}

sub core_vlan {

    my $server = shift;

    my $brip = $server->{BR_IP};
    my $vnum = $server->{CoreVlanNum};

    for (1..$vnum){

        my $vlanip = $server->{'CoreVlan_IP_'.$_};
        my $vmask  = $server->{'CoreVlan_Netmask_'.$_};

        if ($brip && $vlanip eq $brip){

            my $vlist = join ("/", $brip, $vmask);
            $vlist =~  s/.[0-9]*\//.0\//g;
            push @vlist, $vlist if ! $seen{$vlist}++;
        }
    }
}
[download]