use constant APOSTROPHE =>  "\xE2\x80\x99" ;
my $string =~ s/APOSTROPHE/'/ ;

##</code><code>##

use constant APOSTROPHE =>  "\xE2\x80\x99" ;
my $string = "wjzw’xl cowuxze.";
$string =~ s/APOSTROPHE/'/ ;

##</code><code>##

my $pos = index $string, APOSTROPHE;
substr($string, $pos, length APOSTROPHE) = q{'};

##</code><code>##

#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;
use utf8;
use open OUT => qw{:encoding(UTF-8) :std};

my $string1 = 'abc’def’ghi’jkl';
my $string2 = 'mno’pqr’stu’vwx';

say '*** BEFORE ***';
say "\$string1[$string1]";
say "\$string2[$string2]";

($string1, $string2)
    = @{fancy_apos_to_ascii_apos(\($string1, $string2))};

say '*** AFTER ***';
say "\$string1[$string1]";
say "\$string2[$string2]";

sub fancy_apos_to_ascii_apos {
    my (@fancies) = @_;
    state $fancy_apos = '’';
    state $fancy_apos_len = length $fancy_apos;
    my $asciis = [];

    for my $string (map $$_, @fancies) {
        while ((my $pos = index $string, $fancy_apos) >= 0) {
            substr($string, $pos, $fancy_apos_len) = q{'};
        }

        push @$asciis, $string;
    }

    return $asciis;
}

##</code><code>##

*** BEFORE ***
$string1[abc’def’ghi’jkl]
$string2[mno’pqr’stu’vwx]
*** AFTER ***
$string1[abc'def'ghi'jkl]
$string2[mno'pqr'stu'vwx]