use strict;
use warnings;
use utf8;
use feature 'unicode_strings';

use Data::Dump qw/ dd /;

my $txt;
my $tx1;
my $s_;
my $TestCh1;
my $TestCh2;

binmode STDOUT, ':encoding(UTF-8)';
printf "\x{FEFF}";

# $txt = "This =>\N{U+100049}<= is a Unicode character in Plane 16";
$txt = "This =>&#1048649;<= is a Unicode character in Plane 16";
printf "Dumping \$txt=";
dd( $txt );

$tx1 = $txt;
$tx1 =~ s/"\\N{U+100049}"/"\N{U+2190}"/ge;

print "0:\$txt=" . $tx1;
print "\n";
printf "Dumping \$tx1=";
dd( $tx1 );
print "\n";

$tx1 = $txt;
$tx1 =~ s/\\xF4\\x80\\x81\\x89/"\\N{U+2190}"/ge;

print "1:\$txt=" . $tx1;
print "\n";
printf "Dumping \$tx1=";
dd( $tx1 );
print "\n";

$tx1 = $txt;
$TestCh1 = "\\xF4\\x80\\x81\\x89";
$TestCh2 = "\\N{U+2190}";

($s_ = '"'.($TestCh2).'"') =~ s/&/\$&/g;
print "2:\$s_=" . $s_ . "!, \$TestCh1=" . $TestCh1 . "!, \$TestCh2=" . $TestCh2 . "!\n";

$tx1 =~ s/$TestCh1/eval $s_/ge;
print "2:\$tx1=" . $tx1 . "!\n";
print "\n";
printf "Dumping \$tx1=";
dd( $tx1 );
print "\n";

$tx1 = $txt;
$TestCh2 = "\\xE2\\x86\\x90";
($s_ = '"'.($TestCh2).'"') =~ s/&/\$&/g;
print "3:\$s_=" . $s_ . "!, \$TestCh1=" . $TestCh1 . "!, \$TestCh2=" . $TestCh2 . "!\n";

$tx1 =~ s/$TestCh1/eval $s_/ge;
print "3:\$tx1=" . $tx1 . "!";
print "\n";
printf "Dumping \$tx1=";
dd( $tx1 );
print "\n";
__END__
Dumping $txt="This =>\x{100049}<= is a Unicode character in Plane 16"
0:$txt=This =>&#1048649;<= is a Unicode character in Plane 16
Dumping $tx1="This =>\x{100049}<= is a Unicode character in Plane 16"

1:$txt=This =>&#1048649;<= is a Unicode character in Plane 16
Dumping $tx1="This =>\x{100049}<= is a Unicode character in Plane 16"

2:$s_="\N{U+2190}"!, $TestCh1=\xF4\x80\x81\x89!, $TestCh2=\N{U+2190}!
2:$tx1=This =>&#1048649;<= is a Unicode character in Plane 16!

Dumping $tx1="This =>\x{100049}<= is a Unicode character in Plane 16"

3:$s_="\xE2\x86\x90"!, $TestCh1=\xF4\x80\x81\x89!, $TestCh2=\xE2\x86\x90!
3:$tx1=This =>&#1048649;<= is a Unicode character in Plane 16!
Dumping $tx1="This =>\x{100049}<= is a Unicode character in Plane 16"