if ($hash{$var1} == $var2) {
  print "You are in\n";
}
else {
  print "Bad, monkay, bad!\n";
}

##</code><code>##

if (defined($var1)) {
 ...
}

##</code><code>##

if (defined($hash{$var1}) && length($hash{$var1}) > 0) {
 ...
}