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

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";

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

print "0:\$txt=" . $tx1;
print "\n\n";

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

print "1:\$txt=" . $tx1;
print "\n\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";

$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 . "!\n";
print "\n";