utf8x vs. utf8 (inputenc)

Question

I normally use \usepackage[utf8]{inputenc} for my latex document but on this site i saw a lot of code with \usepackage[utf8x]{inputenc}.

What are the differences between the 2 options ?

Is there one of the option obsolete and which one should I use ?

Answer 1

The simple answer is that utf8x is to be avoided if possible. It loads the ucs package, which for a long time was unmaintained (although there is now a new maintainer) and breaks various other things.

The best way to deal with unicode source (especially with non-latin scripts) is really XeLaTeX or LuaLaTeX.

There's an extended discussion of this here: Encoding remarks. See especially the comments by Philipp Lehman and Philipp Stephani.

Answer 2

"The simple answer is that utf8x is to be avoided if possible." Yes and No. No it's not so simple utf8x is sometimes necessary when you need to write greek or some special symbols. Yes utf8x is for a long time was unmaintained but we can use it. Try to compile the next code with utf8

\documentclass{article}

\usepackage[utf8x]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[polutonikogreek,english]{babel}

\renewcommand*{\textgreek}[1]{%
  \foreignlanguage{greek}{#1}%
}

\begin{document}

This is english
\textgreek{Τηις ις γρεεκ}
This is english again.

\end{document}

Answer 3

I've had the experience of not being able to compile Hebrew with utf8, only with utf8x, using pdflatex in MikTeX (e.g. 2.9). Many guides on writing Hebrew LaTeX suggest using utf8x:

• ivritex
• A Hebrew wikibook on LaTeX
• The Hebrew Wikipedia LaTeX article
• Yoav Goldberg' Hebrew LaTeX tips page at BGU
• etc.

This is not to contradict what the learned sages say above, it's just an example of a case in which it seems to be impossible to avoid (unless someone suggests a way like Ulrike's suggesting regarding Greek).

Answer 4

In fact, utf8 may not be as restrictive as it seems: it only loads characters that can be displayed by the font encoding.

When typing

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

the font encoding is still OT1 when loading inputenc, which has very few characters. By using

\usepackage[T1]{fontenc} 
\usepackage[utf8]{inputenc}

you will allow all displayable utf8 characters to be available as input.