Missing number, treated as zero. When attempting define special characters

Question

Looking into multiple threads, I stil cannot seem to solve my error. I therefore hope some of you might be able to help me out?

When attempting to define the three scandinavian letters å æ ø Å Æ Ø with the following code:

\catcode`æ=\active\catcode`ø=\active\catcode`å=\active
\catcode`Æ=\active\catcode`Ø=\active\catcode`Å=\active
\defæ{\ae}\defø{\o}\defå{\aa}
\defÆ{\AE}\defØ{\O}\defÅ{\AA}

I get the following error message when I typeset the document:

./main.tex:63: Missing number, treated as zero.
<to be read again> 

I am using "Classicthesis" and the input is defined as latin9

Hope one of you will be able to help me out here!

Best regards, Henrik

Answer 1

I can reproduce the issue, but only if the input file is UTF-8. If I save it as Latin-9, the definitions are performed without any complaint.

Why is the error issued when the file is encoded as UTF-8? Because in this case what you see as æ is actually two characters, as far as TeX is concerned (it doesn't understand multibyte encodings). Precisely, æ is seen as the pair of bytes <C3><A6>, so what TeX really sees is

\catcode`<C3><A6>=\active

(note that <xy> is used just to represent a single character), which is a bad assignment and indeed will trigger the error message you see. This cannot happen if the file is encoded in a one byte encoding such as Latin-9.

In any case you shouldn't do things like that. Check the file encoding looking carefully to what your text editing program tells you and then add to the document preamble

\usepackage[latin9]{inputenc}

if the encoding really turns out to be Latin-9, or

\usepackage[utf8]{inputenc}

if instead it is UTF-8. Both declarations (when the option agrees with the encoding of the file) automatically do what you want to do manually.

_{I'm under the impression that you're using some template you got from the net or some friend. Don't trust them, particularly if they contain things you know absolutely nothing about.}