Erlang identify umlauts - unicode

Question

How can I identify german umlauts in Erlang? I tried for days now, when I read a text as list it just doesn't get them. I tried this for example
change_umlaut(Word) -> change_umlaut(lists:reverse(Word), []).
change_umlaut([],Acc) -> Acc;
change_umlaut([H|T],Acc) ->
if
%extended ascii characters
H =:= 129 -> change_umlaut(T, ["ue"|Acc]);
H =:= 132 -> change_umlaut(T, ["ae"|Acc]);
H =:= 148 -> change_umlaut(T, ["oe"|Acc]);
%extended ascii characters
H == 129 -> change_umlaut(T, ["ue"|Acc]);
H == 132 -> change_umlaut(T, ["ae"|Acc]);
H == 148 -> change_umlaut(T, ["oe"|Acc]);
%literals
H == "ü" -> change_umlaut(T, ["ue"|Acc]);
H == "ä" -> change_umlaut(T, ["ae"|Acc]);
H == "ö" -> change_umlaut(T, ["oe"|Acc]);
%else
true -> change_umlaut(T, [H|Acc])
end;
it just passes all the arguments without matching until true...
Thank you for your help.

Answer 1

In Erlang, strings usually contain Latin-1 or Unicode codepoints, so you should be looking for 228 for "ä", 246 for "ö" and 252 for "ü".
Your literals section should have made this work transparently, except for the fact that H is a single character, and you're comparing it to strings ("ü", "ä" and "ö"). The corresponding character literals are $ü, $ä and $ö - make sure that your source file is saved as Latin-1 for this to work.