#!/usr/bin/perl 
my $a = "123{12\n";
print "ACK digit! per cazz posix\n" if ($a =~ /[:^digit:]/);
print "\npast cazz posix\n";

print "ACK digit! per ww-digit-posix\n" if ($a =~ /[^:digit:]/);
print "\tpast ww posix\n";

print "ACK digit! per ww-ISdigit-posix\n" if ($a =~ /[^:isdigit:]/);
print "\tpast ww ISdigit-posix\n";

print "ACK ISdigit! per cazz-ISdigit-posix\n" if ($a =~ /[:^isdigit:]/);
print "\npast cazz ISdigit posix\n";

print "ACK \\D!\n" if ($a =~ /\D/);

##</code><code>##

print "ACK digit! per ww-ISdigit-posix\n" if ($a =~ /[[^:isdigit:]]/);  #changed; dbl brkts