- mb_detect_encoding: documentation ( source)
<?php
$str = 'qqтест12qq';
$str_win = iconv('utf-8', 'cp1251//IGNORE', $str);
echo mb_detect_encoding($str, 'CP1251, UTF-8');
echo mb_detect_encoding($str_win, 'CP1251, UTF-8');
echo iconv('utf-8', 'cp1251//IGNORE', $str);