#!/usr/bin/env perl
use warnings;
use strict;
use Term::ReadKey;

Term::ReadKey::ReadMode 4;

print ": ";
my $c = ReadKey;

if ( $c =~ /[0-9]/ ) {
    print "$c\n";
}

print ": ";
$c = ReadKey;

if ( $c =~ /^[0-9]\z/ ) {
    print "$c\n";
}

Term::ReadKey::ReadMode 0;