my $var = 10; # This is a lexical variable.
$van = 5;     # This is a package global.

##</code><code>##

{
  my $var = 10;
  my $van = 5;
  print "\$var = $var; \$van = $van\n";
}
# Here, $var and $van don't exist.

##</code><code>##

use strict;
use warnings;

my %hash;
$hash{var} = 10;
$hash{van} = 5;
print "var = $hash{var}; van = $hash{van}\n"; 
delete hash{$_} for grep { /^v/ } keys %hash;

print "var = $hash{var}; van = $hash{van}\n";

##</code><code>##

$hash{$_} = undef for grep { /^v/ } keys %hash;