{conditionals} is about macros like \if and \ifx that may execute other macros depending on whether certain conditions are true or not. Popular packages are {etoolbox} and {ifthen}.

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29
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5answers
3k views

Testing for number

How do I test if a given parameter is a number, in order to apply a different style? And if not, just ignore... Like: \domorestuffifnumber{things} -> things \domorestuffifnumber{123} -> ...
16
votes
3answers
789 views

Check if LuaTeX is running

I want to check if my tex document is compiled with LuaTeX (or any other Lua TeX compiler). The simple approach from the TeXbook is to check the \directlua macro against \@empty, like ...
5
votes
2answers
461 views

a/an substitution in LaTeX

I was wondering if there is a conditional command that I can use in LaTeX (e.g., \ifthenelse) that would allow me to, in one case, use the word 'a' and in another use the word 'an' based on the ...
15
votes
1answer
387 views

Conditioning behaviour of a macro on whether on top of a new page

Is there a way to find out, whether the currently typeset material will go to top of a page? I am trying to write a macro which, when invoked, typesets a horizontal divider to separate the subsequent ...
17
votes
1answer
918 views

Conditional pagebreak?

Is there a way I can have LaTeX insert a pagebreak, if the last line of the page is a certain string? e.g. \noindent \textsl{Solution}: thanks very much!
33
votes
5answers
13k views

If Then Else for odd page/even page

How to use if-then-else structure in LaTeX? I need a example of odd and even page. if odd then command 1 else command 2
9
votes
3answers
1k views

How to use the exact same file for handout and presentation modes in beamer

I want to use the exact same file for my beamer presentation and handout. I do not like the need to comment out lines in order to create the handout or presentation (my current solution), nor do I ...
156
votes
4answers
75k views

LaTeX conditional expression

I would like to be able to set a flag at the beginning of the main flag (say output) that tells if I want to produce a paper document or an electronic document. Then I should check this flag to ...
26
votes
4answers
2k views

Redundancy in bib file: conditionally suppress url if same as doi?

Mathscinet gives bibtex entries with both a doi and a url field included. Typically they look something like @article {some-article, […] DOI = {10.1016/j.apal.2008.12.003}, URL = ...
7
votes
2answers
271 views

Nicer way to test that exactly one flag is set

I have a package that takes a long list of boolean flags (currently about 10) in its options, and I want to test if exactly one of these is set to true - something like an XOR for 10+ booleans. The ...
4
votes
1answer
532 views

Booleans fail in tabular environment

I've got a workaround for this problem, but maybe someone knows a cleaner way to fix it. I'm using the standard packages in TexLive 2009. Here's the code that doesn't work: \documentclass{article} ...
6
votes
3answers
671 views

etoolbox conditional causes unwanted empty row in tabular

This code leaves an empty row at the bottom: \documentclass{article} \usepackage{etoolbox} \def\somedef{foo} \begin{document} \begin{tabular}{|l|} \hline First row, not important \\ \hline ...
22
votes
4answers
761 views

Is there an \iftex4ht command, and if not, how should it be defined?

Background: I'm using TikZ to generate a load of pictures that I want to put on the web as SVGs. So I'm using the pgfsys-tex4ht.def driver and it's working very well. My gut feeling is that the SVG ...
17
votes
4answers
3k views

Making switch/case with etoolbox's \ifdefequal

I've got a define such as \def\doctype{SomeString}. \doctype can take on one of five values. I want to do something like a switch statement in a programming language, i.e. (pseudocode): switch ...
36
votes
6answers
7k views

Is it possible to keep my translation together with original text?

I have an English article in LaTeX, which I'm going to translate to Russian. I want to keep my translation in sync with the original text. It means that I want every paragraph to stay as close to its ...
11
votes
2answers
270 views

What is “dimen” in the documentation for the ifthen package?

In the documentation for the ifthen package, there is a test called \lengthtest which compares two <dimen> parameters with the operators <, > or =. (For other test commands, <dimen> ...
21
votes
4answers
2k views

Detect beginning of a sentence in a macro for capitalization

Is it possible to make macros give different results at the beginning of a new sentence? Suppose that I want the macro "\secname" to write "Section" at the beginning of a new sentence, and "section" ...
11
votes
2answers
10k views

Tikz/Pgf if statements

I'm having trouble writing if statements, I can find next to no documentation on them and what I want to do seems quite simple. I'm using the orbitals pgf/tikz example from here, and I'd like to ...
4
votes
3answers
2k views

How to use \newcommand for \href?

I want to format Wikipedia entries in my document in a standard way: \href{http://en.wikipedia.org/wiki/Foo}{Foo} So I thought about using \newcommand*: \documentclass{article} \usepackage{ifthen} ...
6
votes
1answer
624 views

How to display some text based on a condition inside a tabular environment?

I defined a variable \@afwezig that holds people that were not present at a certain meeting. \long\def\@afwezig{} \def\afwezig#1{\def\@afwezig{#1}} Now I want to make the header of the meeting ...
14
votes
2answers
2k views

How do I conditionally execute something based on a documentclass option?

I'd like to conditionally do some things (like input a file) depending on if a specific class option was passed. For example, I'd like to have an "instructor" option to the class that would input a ...
29
votes
6answers
5k views

Test whether token list is empty

Is it possible to test whether a token list register is empty without expanding it?
2
votes
1answer
508 views

\newcommand that restricts the value of an argument

When defining a macro, is it possible to restrict the value of an argument, so that if the thing followed it is a number, then it takes it as an argument, but if it is not, then it is just empty. To ...
35
votes
4answers
11k views

How to conditionally define a new command in LaTeX?

I'm trying to compile a LaTeX code with an older version of some package. Thus, I'm having a few issues due to undefined commands. How can I add conditional code so that I can define some work-around ...
6
votes
1answer
970 views

Using versions environment tags inside a new environment definition

I just found out about the versions package here and am interested in using it to hide solutions in a problem set document. Recall that, to create versions block, in the preamble, you need ...
12
votes
1answer
676 views

Loading a package conditionally

Is it possible to load some package from a .sty file only if some option is selected? (Naive approach \DeclareOption{something}{\RequirePackage{something}} doesn't work.)
62
votes
6answers
3k views

Which document class is being used?

Is there a way to programmatically determine which document class is in effect? I'd like to be able to write conditional macros that behave differently depending on which document class is currently ...