{catcodes} is about "category codes" — an integer number from 0–15 associated to each of the 256 character codes. The category codes indicate the role of a character.
144
votes
1answer
15k views
What do \makeatletter and \makeatother do?
Many TeX “hacks” begin with \makeatletter and end with \makeatother. What do these commands do?
12
votes
4answers
2k views
How to make a real backslash (escape) character?
I just want a good way to make a backslash character (or whatever character(s) any given format uses as escape characters), suitable to \write to a file or pass to a pdfTeX primitive.
Let me ...
25
votes
3answers
676 views
Using indentation to automatically begin and end itemize environments
This is a question one might answer with "Why the hell would you want to do it?!", sort of an experiment.
What I am looking for is a way to write lists with many levels of nestings (notes for school) ...
6
votes
3answers
508 views
Changing the catcode of _ in one command?
In the following code, I would like _ to be a simple letter. How can I achieve this ?
% Source : http://forum.mathematex.net/latex-f6/forcer-le-retour-a-la-ligne-dans-texttt-t13246.html#p127511
...
25
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4answers
928 views
What are category codes?
Following on from this question, I'd like to ask a more general question:
What are category codes, and what can I achieve by changing them?
10
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2answers
419 views
Removing a backslash from a character sequence
For indexing I wanted to write a macro \macroname that removes leading backslashes from macro names but leaves the names of environments untouched. That is
\macroname{\relax} --> relax
...
5
votes
2answers
144 views
Changing catcode for commercial at (@) inside a macro to get it matched in pattern.
This question is related to TikZ: pgfutil-common: pgfutil@in@ - how does it work? and is a result of coping with that problem. I've already read How to change #catcode in a macro, but it didn't help ...
6
votes
2answers
255 views
Active characters after \begin{document}
I'm using XeLaTeX and I want to do automatic repeating of plus sign after breakline. I've found the unoffical package for this but it seems to me a bit overkill (although didn't try it).
I tried to ...
12
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1answer
326 views
How to redefine @ and . to obfuscate email addresses?
I am writing a small package containing macros I intend to use regularly. Among those macros, I have \mailto with the following definition:
\@ifpackageloaded{hyperref}{%
\def\mailto#1{%
...
7
votes
1answer
193 views
Catcodes of unicode characters with \usepackage[utf8]{inputenc}
I don't understand why this is generating an error message...
\documentclass{article}
\usepackage[utf8]{inputenc}
\begin{document}
\catcode`ẟ=\active
\end{document}
As the inputenc suggests, I'm ...
9
votes
4answers
468 views
How do I get the category code of a character that is the value of a control sequence?
How can I get the category code of a character that is the value of a control sequence?
If I do this
The catcode for A is \the\catcode`A.
I get
The catcode for A is 11.
If I do this
\let\abc=A
...
27
votes
1answer
2k views
Is it \catcode or \catcode`?
I've noticed that \catcode is poorly documented in the TeXbook. The primitive is defined as \catcode but every time it is used, it is used as \catcode` ... the backquote is never discussed. ` itself ...
28
votes
2answers
585 views
No \makeatletter required?
In typing up some small examples that might create errors in LaTeX (for Documents with typical LaTeX errors), I tried the following:
\documentclass{article}
\def\my@macro#1{-#1-}% This is magic
...
15
votes
1answer
106 views
What is the differences between mathcode and catcode and how can I use mathcode?
The command \catcode is often used to change some internals. E.g. the command \makeatletter changes the catcode @. But what is \mathcode and how does it work?
catcodes are well explained here: Wiki ...
9
votes
2answers
407 views
How to get the catcode of a token?
For debugging a complicated macro I would like to print out the catcode of a token. Optimally I would like to have a macro \getcatcode such that, for example, \getcatcode{a} would expand to 10. How ...
8
votes
1answer
404 views
How to change #catcode in a macro
I want to change the catcode in a macro, but it seems it doesn't work. Can anyone help me?
\def\A{\catcode`\|=0 |bf{test}}
|bf{test} would not work as expect.
3
votes
1answer
115 views
Use catcode for alternative way of writing fractions
Writing fractions using different syntax would sometimes be useful, instead of using \frac{ab}{cd}, I would prefer to write something like
\frac{ab⌂cd}
where the Unicode ⌂ is the }{.
n.b., I don't ...
18
votes
2answers
352 views
How bad is slack \makeatother discipline really?
Following Will Robertson's admission that Fwiw, i'm not aware of any troubles with a missing \makeatother, but you're right. It's a bad habit of mine to omit it, and my own progressive slackness about ...
12
votes
2answers
257 views
Macro to take a character as argument, make it active, then \def it.
I have a XeLaTeX document in which I want some unicode symbols to be auto-substituted, like ¼ → 1/4, » → >>, « → <<. But instead of a long list like
\catcode`\¼=\active\def¼{1/4}
...
6
votes
1answer
307 views
catcode as used in defining Hypergeometric Function
This is perhaps not a very intelligent question, as I am not (of great intelligence nor) well versed in raw tex, even more so \catcode but in the code given in a previous answer there is a use of ...
11
votes
1answer
146 views
Can the makeatletter/makeatother mechanics lead to parsing problems?
The reason for using \makeatletter/\makeatother has been discussed in many places, for instance in this question.
However I think that this trick of playing around with the "@" character is itself ...
7
votes
1answer
249 views
Is there a counterpart/antidote for \obeylines?
The \obeylines command tells TeX to preserve line endings, which is useful for poetry and various other things. I can limit the effect of \obeylines by wrapping it in a scope, like so:
{\obeylines
...
6
votes
1answer
357 views
\input only part of a file using catchfilebetweentags package
I would like to include only a part of a .tex file into a different .tex file. The part I want to include is delimited by some comment tags, as it is used by catchfilebetweentags package.
I tried the ...
3
votes
1answer
112 views
Expanding subscript and subscript capabilities
Well, I liked the idea expressed in the question alternative syntax of subscripts using tex. But I want it to work in a sightly different way.
I just want to expand the usual _ and ^. How? So that ...
3
votes
2answers
373 views
How listing and verbatim do to escape special character?
I use one macro to display text using texttt style. For the moment this macro is very basic. For example, if I want to use the character _, its catcode must be changed.
Is there a clever way to ...
2
votes
1answer
72 views
Macros and environments that rely on the distinction between space and newline
In most cases, TeX does not distinguish between spaces and newlines. However, inside some macros and environments this distinction matters a lot. Time for a big list? Please edit the CW answer.
This ...
