原链接：https://www.jb51.net/article/70251.htm

/**
 * utf8字符转换成Unicode字符
 * @param [type] $utf8_str Utf-8字符
 * @return [type]      Unicode字符
 */
function utf8_str_to_unicode($utf8_str) {
  $unicode = 0;
  $unicode = (ord($utf8_str[0]) & 0x1F) << 12;
  $unicode |= (ord($utf8_str[1]) & 0x3F) << 6; $unicode |= (ord($utf8_str[2]) & 0x3F); return dechex($unicode); } /** * Unicode字符转换成utf8字符 * @param [type] $unicode_str Unicode字符 * @return [type] Utf-8字符 */ function unicode_to_utf8($unicode_str) { $utf8_str = ''; $code = intval(hexdec($unicode_str)); //这里注意转换出来的code一定得是整形，这样才会正确的按位操作 $ord_1 = decbin(0xe0 | ($code >> 12));
  $ord_2 = decbin(0x80 | (($code >> 6) & 0x3f));
  $ord_3 = decbin(0x80 | ($code & 0x3f));
  $utf8_str = chr(bindec($ord_1)) . chr(bindec($ord_2)) . chr(bindec($ord_3));
  return $utf8_str;
}

$utf8_str = '我';

//这是汉字“你”的Unicode编码
$unicode_str = '4f6b';

//输出 6211
echo utf8_str_to_unicode($utf8_str) . "
";

//输出汉字“你”
echo unicode_str_to_utf8($unicode_str);