- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$str_utf8 = 'Qwпарольww11';
$str_cp1251 = iconv('UTF-8', 'Windows-1251', $str_utf8);
var_dump(preg_match('#[а-яА-Я]#u', $str_utf8));
var_dump(preg_match('#[а-яА-Я]#u', $str_cp1251));
echo $str_cp1251;
?>