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### weird ifnum with compact syntax [duplicate]

In some packages like tabularx, I find the following syntax in many places {\ifnum0=`}\fi or even \ifnum0=`{\fi} But I can't figure out why this can be useful for? Is ` a register of some kind? ...
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### What is \iffalse for?

So this is something I've wondered about for a while. What use is a conditional that always evaluates to false? I guess it's a neat way to "hide code from LaTeX" but apart from that, is it ever useful?...
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### Where do I find \futurelet's nasty behaviour documented?

Until recently, I thought that execution of \futurelet\testtoken<token1><token2>... has the following effect: The control sequence \testtoken is \let to <token2> and \futurelet\...
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### TeX macro idioms, or: understanding advanced macros

I often find that when I look at solutions from the experts here, the macro definitions are completely inscrutable to me. Trying to use standard techniques one would use to understand code in most ...
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### When might it be helpful to use implicit braces instead of explicit braces?

We've covered the question "When can one use implicit braces instead of explicit braces?"; this leads immediately in my mind to the question "Why would one want to?" (Remember, implicit braces are e....
439 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 >{\collectcell\mymacro}c<{\...
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### Replace chars with xstring. Catcode problem

I try to do something like this (minimal example): \documentclass[]{article} \usepackage{mathtools} \usepackage{xstring} \newcommand{\foo}[1]{ \StrSubstitute{#1}{:}{\string&}[\fooo] \...
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### how to lower last term in a continued fraction after a diagonal row of dots?

How can I lower the last term of a continued fraction when it follows a diagonal row of dots?