C:\>type getopt.pl

use Getopt::Std;
our($opt_p);
getopt('p');
print "Using the getopt() method \$opt_p is ";
print defined $opt_p ? "'$opt_p'" : "undefined";

C:\>perl getopt.pl
Using the getopt() method $opt_p is undefined

C:\>perl getopt.pl -p
Using the getopt() method $opt_p is undefined

C:\>perl getopt.pl -p123
Using the getopt() method $opt_p is '123'