#! /usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my $string = "\N{LATIN SMALL LETTER A WITH GRAVE}";
say length $string;     # 1

{
    use bytes;
    say length $string; # 2
}

open my $OUT, '>:utf8', '1' or die $!;
print {$OUT} $string;
close $OUT;

no utf8;
open my $IN, '<:utf8', '1' or die $!;
my $char = <$IN>;
say length $char;       # 1
say $char eq $string;   # 1

use utf8;
open $IN, '<', '1' or die $!;
my $bytes = <$IN>;
say length $bytes;      # 2
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utf8 tells Perl that the source code uses UTF-8. length is sensitive to bytes and to the UTF8 flag of its argument.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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