- mb_strpos: documentation ( source)
- mb_convert_encoding: documentation ( source)
- var_dump: documentation ( source)
- hex2bin: documentation ( source)
<?php
var_dump(
$a = hex2bin("1b204422433222ebbb1b2842"),
mb_convert_encoding($a, "UTF-8", "ISO-2022-JP"),
mb_strpos($a, "?", 0, "ISO-2022-JP")
);