use strict;
use warnings;

while (1) {
    <STDIN>;
    m/./ and print "success.\n";
    # ... (more code) ...
}

##</code><code>##

Use of uninitialized value in pattern match (m//) 
at uninit.pl line 6, <STDIN> line 1.

##</code><code>##

use strict;
use warnings;

while (<STDIN>) {
    m/./ and print "success.\n";
    # ... (more code) ...
}