{tex-core} is for questions that are independent of formats and macro packages. Such questions usually relate to low-level TeX programming or the behaviour of TeX at an underlying level. Note that even Plain TeX is a format in itself; for questions about it, use {plain-tex}.

learn more… | top users | synonyms (1)

15
votes
1answer
488 views

How do I ‘expand’ a control sequence `\let` to a character?

Consider the following: \let\1=X \edef\2{\1} \show\1 \show\2 The result is > \1=the letter X. > \2=macro: ->\1. Is it possible to ‘expand’ the meaning of \1 so that \2 contains just ...
15
votes
1answer
231 views

Am I programmatically tieing my hands behind my back by insisting on a particular engine?

I've read Differences between LuaTeX, ConTeXt and XeTeX, but still have a niggle at the back of my mind that I'd like to ask about. I'm developing a LaTeX package/class/stuff with the aim of making ...
14
votes
7answers
2k views

Can I see a plain TeX source file please?

all the LaTeX-tutorials tell me how LaTeX is an extention simplifying the building of TeX documents. Understandably, no one uses plain TeX anymore, right? But I seem to learn better when I grasp the ...
14
votes
2answers
1k views

Which “TeX” should one use?

This question is from my confusion with the editor. In the WinEdt 6.0, there is a button for different kinds of "TeX". How do I know which one I should use and what's the difference?
14
votes
3answers
3k views

What is the difference between \empty and \@empty?

I want to elaborate a command that would print differently simple differential dx and multidimensional differential d^3x. For this purpose I invented the command \dif with one optional argument. It is ...
14
votes
2answers
1k views

Breakable vboxes

In Plain TeX how can I make vboxes breakable, and can I handle/measure them separately? What I'm trying to do, is that I have a portion of text, that is treated separately (no indention, narrower, ...
14
votes
2answers
527 views

Why using character ^^ff before every chapter in the TeXBook source

When viewing the source code of the TeXBook, I find that there is a character ^^ff before every chapter in it. I am wondering why using this ^^ff character which seems useless? The following ...
14
votes
3answers
884 views

TeX macro and command expansion?

I have implemented couple of macros that should remove commas from numbers. It's nasty dirty stuff, but it works when input is number: \removecommas{12,34,56.7} % => 123456.7 But it stop working ...
14
votes
3answers
667 views

Is there a printable version of a reference manual for all TeX primitives?

Everywhere in the TeX community, I see suggestions like \parskip, \obeylines, \parindent, etc. I'd be surprised not to find them even in the most basic LaTeX packages. So I figured they must be deeper ...
14
votes
2answers
230 views

How can own commands be aware of \global?

When I define a command that defines commands \def\makefoobar{ \def\foo{foo} \def\bar{bar} } and prefix it with \global { \global\makefoobar } it is treated like { \global\def\foo{foo} ...
14
votes
2answers
989 views

Is a TeX macro defined?

I am looking for a way in TeX to check if a macro was defined. Currently I use a rather tangled way. I exploit a sort of side effect when comparing two macros via \ifx; this command returns: true, ...
14
votes
2answers
543 views

What is “plain TeX”?

I occasionally see a statement that plain TeX is not the same as TeX, because plain TeX is already a format. What is plain TeX, and what is the difference to TeX proper? Some answers are here (The ...
14
votes
2answers
176 views

Can I get at stuff in “current page” or “recent contributions”?

When I compile the following, \documentclass[a4paper]{article} \usepackage{atbegshi} \AtBeginShipout{\showlists} \showboxdepth\maxdimen \showboxbreadth\maxdimen \usepackage{lipsum} ...
14
votes
3answers
238 views

How to determine which register a count uses

Suppose there is \newcount\c@mycountera \newcount\c@mycounterb \newcount\c@mycounterc Each \newcount uses \alloc@ and that has \wlog{\string#5=\string#2\the\allocationnumber}. Thus to determine ...
14
votes
2answers
290 views

How to set tikzmarks with \noalign at the edge of tabular rows

I'm trying to improve the lines in a tabular with colored rows (lines above a colored row can disappear in the adobe reader at some zoom levels) by redrawing the line above a row after the row itself ...
14
votes
3answers
1k views

How can I open a file in “append” mode?

Could not find anything in the TeXBook, but this could be just me. I guess it is always possible to open the file for reading, copy its content to another file, and then continue writing to that ...
14
votes
2answers
363 views

Every possible \meaning that a token can have

In the context of a debugging package that I am writing, I need to analyse an arbitrary token in the input stream. What are the possible outcomes of \meaning<token>? Macro: (\protected) ...
14
votes
2answers
1k views

Globally redefining 1 pt to 1/72 in (PostScript point) and other similar changes

Introduction TeX point (1 pt in TeX) equals 1/72.27 in (= 2540/7227 mm ≈ 0.35145980351 mm). Quoting part of Traditional American point system section from Wikipedia's Point (typography) entry: In ...
14
votes
2answers
626 views

Why is \baselineskip not inserted before an \unvbox?

It seems that \setbox0=\vbox{\hbox{abc}}\unvbox0 is not equivalent to \hbox{abc}: the former does not insert a \baselineskip in the following situation. \vbox{% \hbox{XY}% \hbox{abc}% ...
14
votes
1answer
821 views

What is the command \span?

I have bumped into the \span primitive a couple of time. I got the impression it is defined in the TeX program, not even in plain.tex. Is that right? And what does that command do and what is it for?
14
votes
1answer
211 views

How to actually close a write-stream

I don't know too much about writing and reading to and from files. But I managed to create a nice command for me where I need to write something into a text-file and later-on read it again. ...
14
votes
2answers
1k views

Write to log without wrapping

I'd like to to generate some metadata in the log file that I can copy to another application. But the log file is wrapped to 80 columns and I end up with newlines embedded in what I'm putting there. ...
14
votes
2answers
222 views

Use TeX macros to store multiple data

I'm trying to use TeX macros to store multiple data such as website url/name. Here is an example : \documentclass{article} \def\Google{{http://www.google.com}{Google Search}} \makeatletter ...
14
votes
2answers
214 views

What is the easiest way to modify catcodes in a string?

Assume that a token register contains a sequence of letter tokens, each having a catcode of 12. I want to store in a second token register the same sequence of letter token, altering some catcodes on ...
14
votes
1answer
255 views

What practices are there regarding the use or avoidance of “internal” TeX or LaTeX commands?

What practices are there regarding the use or avoidance of "internal" TeX or LaTeX commands? (About "command" vs "macro", there is some discussion in this TeX.SX answer, though I don't know whether ...
14
votes
1answer
478 views

How to print and assign category codes?

Consider the code below, which after giving me some trouble (especially with catcode 9 and 15), prints all the category codes up to catcode 15. \documentclass{minimal} \parindent0pt \begin{document} ...
14
votes
1answer
239 views

How to read a stream of tokens up to one of two different delimiters

The core question How can I process text delimited by one of two terminators? For instance, if I want to process text up to the next \A, I can just write \def\CmdA#1\A{...} But suppose that \A ...
14
votes
1answer
1k views

How to transpose a table in expl3

I've been very impressed with xparse and expl3, and have written a wonderful document command using \ProcessList that takes a comma separated list and turns it into a (basically) 1 column table. ...
14
votes
1answer
815 views

How to change \hsize in the middle of a paragraph at pagebreak, especially for two-column?

The original question is: How to get two columns with different width in LaTeX? I know this older question: How can I create a two-column layout with different widths (and texts) for the two columns? ...
14
votes
2answers
680 views

Active characters let to a (non-active) character

It seems that if I \let\amp&, the alignment tab & can be replaced by \amp everywhere (e.g., in the preamble and in the body of an \halign). It is also possible to make the character & ...
14
votes
1answer
197 views

Can one determine the first character of a given math list?

I'm still pursuing my quest to code a better \widebar command. I can do bars over single characters quite well already, but I have problems when it comes to letter combinations such as AW. ...
13
votes
5answers
294 views

Checking if a string contains # with its original catcode

At comp.text.tex the following scheme was suggested for testing if a string contains the parameter character with catcode 6. \def\endcheck{\endcheck} \def\second#1#2{#2} ...
13
votes
2answers
857 views

Can the PostScript language be used to fully replace TeX? [closed]

THE POSTSCRIPT® LANGUAGE is a simple interpretive programming language with powerful graphics capabilities. ... Because of the importance of text in most applications, the PostScript ...
13
votes
2answers
270 views

How does math mode work?

When writing an a in TeX, it is typeset as an upright "a" by default. When writing an a in math mode it is typeset in italics. Furthermore, in math mode white spaces are ignored and no empty lines ...
13
votes
3answers
738 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 ...
13
votes
4answers
1k views

Dividing dimensions to get a count

Is there a way to divide two dimens and get a count? For example, if I have a box that doesn't fit on a single page, and I want to know the number of pages I'd need for the box (i.e., \heightofbox / ...
13
votes
4answers
1k views

Making efficient use of \writes

I'm currently trying to compile my thesis using LaTeX and have run up against the old ! No room for a new \write . problem. After some googling it seems the only way to actually resolve this problem ...
13
votes
2answers
1k views

Why (La)TeX can not work with true type fonts?

I know that if one wants to use true type fonts, there are solutions via xelatex or lualatex. My question however is, why it is like so? What is the fundamental difference between latex fonts and ...
13
votes
1answer
954 views

What does the \the\everypar do?

If you test the following minimal it does not produce an error. What does it actually do? \the\everypar \bye Why doesn't it produce an error as one would expect?
13
votes
2answers
777 views

The revenge of the vboxes

Yes, they're back. With a vengeance. Those pesky little buggers we call \vboxes which I've fought against previously. (And Bruno, too.) \parskip=0pt \def\unquo{\unvbox0\smallskip} ...
13
votes
2answers
289 views

How are dashes implemented in TeX?

How does LaTeX implement the differences between the dashes? -, --, and --- all print different dashes, but - is not an active character: it has catcode 12, the same as digits like 2.
13
votes
3answers
349 views

Expansion of first token in a tabular cell

Background I currently do some work on the collcell package which collects the content of a tabular/array cell and provides it to a user defined macro, e.g. using ...
13
votes
3answers
277 views

What other macros like \pdffilesize exist?

So I just learned about \pdffilesize from this answer. Are there other similar things like this? I learned about \the\inputlineno a while ago which prints the line number of the input file. In ...
13
votes
2answers
527 views

\expandafter within a \begingroup … \endgroup [duplicate]

Possible Duplicate: What does \begingroup\expandafter…\endgroup do? In many of Heiko Oberdiek's packages one sees this type of construction: ...
13
votes
2answers
637 views

All about \shipout

While reading about packages that allow to hook macros to certain events, I came across this command, \shipout. Searching on the internet didn't help a lot but if I'm not so wrong it's somehow related ...
13
votes
3answers
696 views

Can I make a command not gobble spaces?

(I'm using ConTeXt, but I suspect the answer will lie in plain TeX.) I've created an environment that takes one argument myBufferName, and stores its contents in a buffer of that name. Unfortunately, ...
13
votes
1answer
737 views

Using \toks registers

I was reading this tutorial for TeX programming: http://pgfplots.sourceforge.net/TeX-programming-notes.pdf recommended in the 2-nd answer here: Where do I start LaTeX programming? It says: ...
13
votes
2answers
252 views

ifx, macros and grouping

I do not understand how \ifx interacts with macro definitions. Here is a minimal example: \def\a#1{\b} \def\b#1#2{[#1:#2]} \a ABC The output is [B:C], as expected. If I change the definition of \a ...
13
votes
2answers
647 views

How to use tex -ini, tex -fmt, initex and fmtutil?

What are the roles of each of these commands? What is the good command to create a new format ?
13
votes
2answers
248 views

Difference between one glue and two glues after each other

Is there a difference between A\hskip 1pt \hskip 0pt plus 1fil B and A\hskip 1pt plus 1fil B ? Are these two glues the same in terms of spacing and (line-)breaking? Or do they just add up, as I ...