use strict;
use warnings;

my $numClients;

while ( (print "Enter Number of Clients: "), $numClients=<STDIN>,
         $numClients !~ /^\s*(?:[0]*)?[1-9]\d*\s*$/ or $numClients >=100)
{
   print "Your input is NOT a positive integer less than 100!\n";
}


$numClients += 0;  #optional conversion to numerio
print "Number of Clients: $numClients\n";

__END__

C:\PerlProjects\Monks>perl getposinteger2.pl
Enter Number of Clients: 123
Your input is NOT a positive integer less than 100!
Enter Number of Clients: 5
Number of Clients: 5