Icelandic, utf8 and utf8x in LaTeX

Question

First of all, what\'s the difference between utf8 and utf8x in

\\usepackage[utf8]{inputenc}
\\usepackage[utf8x]{inputenc}

whe

Answer 1

[UTF8] is "supported" by the LaTeX team and covers a fairly specific/limited range of unicode input characters. It only defines those symbols that are known to be available with the current font encoding.

[UTF8x], AFAIK, is no longer supported, but covers a much broader range of input symbols. I would recommend only trying it if [UTF8] doesn't do what you need.

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Secondly, the listings package (and most other related packages that do character scanning) does not support UTF8 input. (If it's working on a friend's machine they must be using an 8-bit input encoding instead.) The listingsutf8 package provides a UTF8-compatible replacement for \lstinputlisting but not for the main lstlisting environment. Using XeLaTeX might help you here, however.