#! /usr/bin/perl -w
use strict;

main->foobar($ARGV[0]);

sub foobar {
  print "foo$_[1]bar\n";
}

##</code><code>##

Use of uninitialized value in concatenation (.) or string at - line 7.
foobar

##</code><code>##

#! /usr/bin/perl -w
use strict;

main->foobar($ARGV[0]);

sub foobar {
  if ($_[1]) {
    print "foo$_[1]bar\n";
  } else {
    print "foobar\n";
  }
}

##</code><code>##

#! /usr/bin/perl
use strict;
use warnings;

main->foobar($ARGV[0]);

sub foobar {
  no warnings qw (uninitialized);
  print "foo$_[1]bar\n";
}