PHP problem with Bulgarian-MIK character set, cant get one letter - php

Question

I know that Bulgarian-MIK character set can be converted with the ord function and adding 64, and the bulgarian-MIK characters are from 127 to 191 but i cant get the letter "а"(ord - 127).I tried a lot of ways but it seems that php is processing "а" with a blank symbol and i cant get it.
define("PHP_NL", "<br>");
$string = '-------------- 1 --------------'.PHP_NL;
$string .= '413 …±Ї°Ґ±® €¶® X1.000'.PHP_NL;
$string .= '358 ЊЁ­ ‚®¤  0.5 X1.000'.PHP_NL;
$string .= '--------------------------------'.PHP_NL;
$string .= '1 -Ђ¤°Ё ­  - ЊЂ‘Ђ: 1 - 6'.PHP_NL;
$string .= '17-08-2018 09:05:32'.PHP_NL;
$string .= '--------------------------------';
That is my string with Bulgarian-MIK encoding.I tried to convert it and i every letter is converted fine, but only "а" i cant get.
My function
function ConvertDosToWin($string) {
$chr = null;
for ($i = 1;$i<strlen($string);$i++) {
$chr = mb_convert_encoding($string[$i],'utf-8','windows-1251');
if((ord($chr) >= 127) && (ord($chr)<=(127+64)) ) {
echo 'inside if';
$string[$i] = chr(ord($chr)+64);
}
}
return $string;
}

Answer 1

I fixed the problem using iconv.
function ConvertWinToDos($string) {
$chr = null;
for ($i = 1;$i<strlen($string);$i++) {
$string = iconv(mb_detect_encoding($string,mb_detect_order(),true),'windows-1251',$string);
$chr = $string[$i];
if ((ord($chr) >= 192) && (ord($chr) <= 255)) {
$string[$i] = chr(ord($chr) - 64);
}
}
return $string;
}

Answer 2

I think that this approach may help. I used this in an old project and next is working example. PHP file is Windows-1251 encoded. If your text is in different encoding, you need to convert text using mb_convert_encoding() or iconv(), because ord() returns the binary value of the first byte of text as an unsigned integer between 0 and 255.
Test.php:
<?php
// Functions
function ConvertDosToWin($string) {
$chr = null;
for ($i = 0; $i<strlen($string); $i++) {
if ((ord($chr) >= 128) && (ord($chr) <= 191)) {
$string[$i] = chr(ord($chr) + 64);
}
}
return $string;
}
function ConvertWinToDos($string) {
$chr = null;
for ($i = 0; $i<strlen($string); $i++) {
$chr = $string[$i];
if ((ord($chr) >= 192) && (ord($chr) <= 255)) {
$string[$i] = chr(ord($chr) - 64);
}
}
return $string;
}
// Output
$text = 'АБВГДЕЖЗИЙ';
$text = ConvertWinToDos($text);
file_put_contents('dos.txt', $text);
?>