Win8 Strawberry 5.8.9.5 (32)  Tue 06/07/2022 22:25:09
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

my $str = '\x{aF}';

$str =~ m{ \A \\ x \{ ([[:xdigit:]]+) \} \z }xms;
my $hex_digits = $1;

print ">$hex_digits< \n";

my $hex_number_in_decimal = hex $hex_digits;
print "$hex_number_in_decimal \n";

^Z
>aF<
175