List of cyrillic characters

Here is code from biblio_theme_inc that returns the list of characters A,B,C, ...Z
for ($i = 65; $i <= 90; $i++) {
if ($i == ord($current)) {
$output .= '[' . chr($i) . '] ';
}
I change the code for it could return me the list of Cyrillic characters
for ($i = 1040; $i <= 1071; $i++) {
if ($i == ord($current)) {
$output .= '[' . chr($i) . '] ';
}
I get instead of Cyrillic characters
!"#$%&.... ..

What I shoul do?