Question

I knew that Lua does not fully support unicode however there should be a workaround to solve this problem?
string.reverse will not work with unicode so the following example will not work

  print(string.reverse("أحمد"))

any help on that?

Answer 1

Corona SDK seems to be using UTF-8 as encoding.

If you want to reverse all Unicode code points in a string, instead of all bytes, you can use that code:

function utf8reverse(str)
  return str:gsub("([\194-\244][\128-\191]+)", string.reverse):reverse()
end

print(utf8reverse("أحمد"))

The trick is as follows: a multibyte Unicode code point always start with a byte 11xx xxxx, followed by one or several bytes 10xx xxxx. The first step is to reverse all bytes on each multibyte code point, and then reverse all bytes.

Note: when a Unicode character is composed of several code points, that simple trick will not work. A full support would require a big Unicode database to deal with.