#!/usr/bin/perl

use Encode;

$regex_raw = 'много';
$text_raw = 'там очень много в городе, вот этих';

$regex_utf8_d = decode( 'iso-8859-5', $regex_raw );
$text_utf8_d = decode( 'iso-8859-5', $text_raw );

# the "_d" scalars have the utf8 flag ON
# perl will treat their values with character semantics


$regex_utf8_e = encode( 'utf8', $regex_utf8_d );
$text_utf8_e = encode( 'utf8', $text_utf8_d );

# the "_e" scalars have the utf8 flag OFF
# this use of encode is unnecessary and counter-productive; 
# it causes perl to treat the values with byte semantics


@labels = qw/raw-raw dec-dec enc-enc dec-enc enc-dec/;

$match{'raw-raw'} = ($text_raw =~ /$regex_raw/);
$match{'dec-dec'} = ($text_utf8_d =~ /$regex_utf8_d/);
$match{'enc-enc'} = ($text_utf8_e =~ /$regex_utf8_e/);

$match{'dec-enc'} = ($text_utf8_d =~ /$regex_utf8_e/);
$match{'enc-dec'} = ($text_utf8_e =~ /$regex_utf8_d/);

for ( @labels ) {
    print "$_ : $match{$_}\n";
}

__OUTPUT__
raw-raw : 1
dec-dec : 1
enc-enc : 1
dec-enc : 
enc-dec :