#!/usr/bin/perl
use strict;
use warnings;
use Encode qw( encode decode );
my $unicode_name_CURRENCY_SIGN = chr(0xa4);

sub _hex {
    my $str = shift;
    join '', map sprintf('%02X', ord($_)), split //, $str;

}

for (qw(ISO-8859-1 ISO-8859-15 windows-1252 UTF-8)) {
    printf "%s %s\n", $_, _hex(encode($_, $unicode_name_CURRENCY_SIGN));
}
__END__
ISO-8859-1 A4
ISO-8859-15 3F
windows-1252 A4
UTF-8 C2A4