LinuxQuestions.org - please help me with this perl code getting error "use of uninitialized value"

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- - please help me with this perl code getting error "use of uninitialized value" (https://www.linuxquestions.org/questions/programming-9/please-help-me-with-this-perl-code-getting-error-use-of-uninitialized-value-708363/)

please help me with this perl code getting error "use of uninitialized value"

hi
i am getting error as:
Use of uninitialized value in concatenation (.) or string at ./iothread.pl line 86, <GEN1> line 1.
during runtime

and
the output looks like this:

Quote:

Multiplex server running on port 4444...
Created thread 1 for new client 10.168.1.2:3233
Use of uninitialized value $_ in scalar chomp at ./iothread.pl line 66, <GEN1> line 1.
1005874632400418
1234
login

Use of uninitialized value in concatenation (.) or string at ./iothread.pl line 86, <GEN1> line 1.
10895
Thread 1 terminated abnormally: Not a CODE reference at ./iothread.pl line 87, <GEN1> line 1.

Code:

#!/usr/bin/perl

# iothreadserv.pl

use warnings;

use strict;

use integer;



BEGIN 

        {

        use Config;

        die "No thread support!\n" unless $Config{'usethreads'};

        }



use Thread;

use IO::Socket;

use DBI;

use DBD::mysql;



# Autoflushing on

$| = 1;

my $port = 4444;

my $server = IO::Socket->new(

        Domain    => PF_INET,

        Proto    => 'tcp',

        LocalPort => $port,

        Listen    => SOMAXCONN,

        Reuse    => 1,

);



die "Bind failed: $!\n" unless $server;

print "Multiplex server running on port $port...\n";



while (my $connection = $server->accept) 

        {

        my $name = $connection->peerhost;

        my $port = $connection->peerport;

        my $thread = new Thread(\&connection, $connection, $name, $port);

        print "Created thread ",$thread->tid," for new client $name:$port\n";

        $thread->detach;

        }

exit;





# child thread - handle connection

sub connection 

{

        my ($connection, $name, $port) = @_;

        $connection->autoflush(1);

        #############################my sql connect###############################

        my $platform = "mysql";

        my $database = "project";

        #my $host = "localhost";

        #my $port = "3306";

        my $user = "root";

        my $pw = "";

        

        # DATA SOURCE NAME

        my $dsn = "dbi:mysql:$database";

        

        # PERL DBI CONNECT

        my $dbh = DBI->connect($dsn, $user, $pw) or die "cannot connect to database";

        

        #######################################################################33



        print $connection "You're connected to the server!\n";

        my $client = <$connection>;

        chomp; # ($client);

        #while (<$connection>) {

        if ($client =~ /::login/)

        {

                print $connection "Login Initiated\n";

                my $rand = int(rand(100000));

                print $connection "Your rand number : $rand";

                #$client =~ s/([\$\@\\])/\\$1/mg; ##escape all $, @ and \

                #$client = quotemeta $client;

                my @recv_string = split /::/ , $client;

                foreach (@recv_string)

                {

                print "$_ \n";

                }

                #next line injection possible !! REMOVE IT!!

                my $sth = $dbh->prepare("select * from Temp_ID where TEMP_NO = $recv_string[0]");

                $sth->execute();

                #take only one output row

                my $ref = $sth->fetchrow_hashref();        

#                $sth->finish();

                print "$ref->{'Temp_ID'} $ref->{'CARD_ID'}\n";

                $sth = $dbh->("select PIN from Cards where Card_ID = $ref->{CARD_ID}");

                $sth->execute();

#                $sth->finish();

                

                my $ref2 = $sth->fetchrow_hashref();

                if ($recv_string[1] eq $ref2->{PIN})

                        {

                        print $connection "PIN verified OK";

                        

                        }

                        

                

        }

        

        if ($client =~ /:logout/)

        {

                print $connection "You are being Logged OUT\n";

        }

        print "Client $name:$port says: $client \n";

              print $connection "Message received OK\n";

        #        }

        $dbh->disconnect;

        $connection->shutdown(SHUT_RDWR);

}

please all ppl out there hel me
i am stuck

Well, if it says:

Code:

Use of uninitialized value $_ in scalar chomp at ./iothread.pl line 66, <GEN1> line 1.

then you'd better look at line 66, right?

Line 66 looks like this:

Code:

chomp; # ($client);

What do you expect that line to do for you? What purpose does it serve in your program?

Quote:

Originally Posted by wje_lq (Post 3461403)

Well, if it says:

Code:

Use of uninitialized value $_ in scalar chomp at ./iothread.pl line 66, <GEN1> line 1.

then you'd better look at line 66, right?

Line 66 looks like this:

Code:

chomp; # ($client);

What do you expect that line to do for you? What purpose does it serve in your program?

I would even ask a more particylar question: "What's the argument of 'chomp' ?".

Quote:

I would even ask a more particylar question: "What's the argument of 'chomp' ?".

In his code, it doesn't have one. But Perl doesn't require that it have one. That's why I'm asking him what he thinks the statement is supposed to do for him.

Quote:

Originally Posted by wje_lq (Post 3461652)

In his code, it doesn't have one. But Perl doesn't require that it have one. That's why I'm asking him what he thinks the statement is supposed to do for him.

Well, if a function doesn't have an argument (but it's not the case), then what does it do ?

Burns CPU time ? Changes a global variable randomly ?

This would be an interesting discussion to have at some point, but right now I'm mainly interested in what haxpak's intention was on line 66. haxpak? You still there?

Quote:

Originally Posted by wje_lq (Post 3461836)

This would be an interesting discussion to have at some point, but right now I'm mainly interested in what haxpak's intention was on line 66. haxpak? You still there?

I don't think there is a place for discussion, but I do think it's worth reading the manual. What about

perldoc -f chomp

?

My question about 'chomp' argument was a very practical one.

Quote:

My question about 'chomp' argument was a very practical one.

I never doubted your intention.

So. haxpak, you still there?

As Sergei Steshenko would ask:

Quote:

What's the argument of 'chomp' ?
As I would ask: what's your intention with line 66?

Code:

chomp; # ($client);

I agree with this line of reasoning: "what is your intention," and, "do you know what your intention is?"

This isn't a "slam" ... isn't public humiliation ... it's necessary in really understanding and solving any problem.

Perl has many "implied arguments," in this case as in many other cases (see perldoc perlvar), which can make it cryptic. But if you can first latch upon the designer's intent, whether "the designer" is you or someone else, the nature of any logic error usually reveals itself quickly.

I would urge you to respond: this is the help you are asking for. Participate. (Others are watching intently.)