#!/usr/local/bin/perl -w
use strict;

while (1) {
    print
"Please enter a single positive integer that represents a number of days, that you wish to convert into seconds. ,(enter q to quit): ";

    chomp (my $days = <STDIN>);
    $days =~ s/\+//;    # allow them to enter +12

    if ($days eq "q") {
        last;
    } elsif (($days =~ /[^\d]/) or ($days eq "")) {
        # days contains an non digit character or is empty
        print "\n!!! You must enter a positive integer.\n\n";
    } else {
        my $seconds = $days * 86400;
        my $plural = ($days == 1) ? '' : 's';
        print "\n$days day$plural = $seconds seconds.\n\n";
    }
}

print "Goodbye\!\n\n";