{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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15
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1answer
386 views

\ifmmode doesn't seem to work correctly inside an array environment

I’m struggling with getting \ifmmode to work correctly when used inside an array environment which is inside a displaymath environment. Here is a minimal example: \documentclass{article} ...
5
votes
2answers
403 views

String test, with complicated arguments

I have a command \mycom{} which takes 1 argument. The command should perform a test on the argument and do something accordingly. For simple arguments, I can use \ifthenelse, but I need to consider ...
33
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2answers
18k views

Conditionally hidden slides in beamer

When creating a presentation, I sometimes create extra slides that contain additional information, a more thorough explanation, or an extra plot pertaining to certain parts of my talk. These extra ...
29
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6answers
5k views

Test whether token list is empty

Is it possible to test whether a token list register is empty without expanding it?
15
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2answers
5k views

Conditional cases expression

How can I create a command \if with 1 argument, namely #1, \if{#1=1}{symbol1}...{#1=n}{symboln} that returns symbol1, when #1 is 1, ..., and returns symboln, when #1 is n, and returns nothing, ...
15
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1answer
371 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 ...
13
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2answers
1k 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 ...
21
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1answer
4k views

Can I test if a file exists? [duplicate]

Can I somehow test if a file exists? And can I use this to do only things when it exists? I like to do something like if(exist('members.csv')) { do something }
18
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2answers
889 views

Check if an entry is cited multiple times

I am trying to find out whether it is currently possible to have a test in Biblatex that tests at the very first time an entry is cited whether the same entry will be cited more than once in the ...
10
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2answers
684 views

biblatex: is there a command analogous to \ifciteseen but within one page?

Biblatex is loaded as \usepackage[style=numeric-comp,hyperref=true]{biblatex} \ExecuteBibliographyOptions{citetracker=true,sorting=none,firstinits=true} I am looking for an if-command, which would ...
6
votes
1answer
683 views

pgfplotstable: Conditional post-processing of cell content on a per-column basis

I am trying to add an asterisk to the content of certain cells depending on the cell's content (essentially, adding a marker for significant p-values) but I am having trouble trying to do so on a ...
5
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1answer
414 views

Counters for use in array/tabular cells

The following practical example \documentclass{article} \usepackage{array}% http://ctan.org/pkg/array \newcounter{tabcol}\newcounter{tabrow} \newcolumntype{C}{>{\stepcounter{tabcol}}c} ...
16
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2answers
872 views

Automatically remove page number if document has only one page (but not if two)

I write a lot of documents (agreements) based on memoir with the article option. Normal pagestyleis plain (page number centered in the footer). Sometimes a document is only one page long, and a page ...
9
votes
1answer
2k views

Bibliographies when using subfiles

I am writing my Ph.D. thesis in XeLaTeX with Biblatex, and there are times when I need to compile individual chapters, and times when I need to compile the entire document, so I use subfiles, which ...
9
votes
1answer
2k views

Using ifthenelse in pgfmath

Following questions on constructing functions on the forum, I tried to build some myself. I can't seem to get the ifthenelse function in TikZ/PGF to work. Here is an example: ...
3
votes
1answer
951 views

Multilingual beamer presentations from a single souce?

I have a beamer presentation of which I have two language versions (german and english), more languages are upcoming. I keep both versions in one source and select the one to typeset with the comment ...
16
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3answers
544 views

What's the use of the @compatibility condition?

All of the standard LaTeX document classes (article, book and report) declare some basic functionality and parameters based on the condition @compatibility. Here's an extract from from article.cls ...
11
votes
1answer
201 views

How can I check if the current code is inside a tikzpicture?

I read the answer for this question (inside a environment) but I would like to know if there is something more specific. LaTeX keeps the current environment in the macro \@currenvir but how do the ...
8
votes
2answers
418 views

How to check if a column type is defined?

Column types for tables can be defined and overwritten with \newcolumntype. I would like to know if a column type is already defined for an example which shall only be executed in the case where the ...
8
votes
1answer
503 views

How do I make make different versions of my document with command line compile flags?

I've found a number of answers online, and plainly none of them have seemed to be able to execute any conditional code. This answer looked particularly promising. One thing I noticed is that in the ...
5
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1answer
208 views

How do I use \ifcommandkey , or how do I check if a key was given?

I'm trying to create a keycommand with optional arguments, but I can't get it to work. I looked at Comparing an argument to a string when argument is a result of a command with etoolbox and although ...
27
votes
3answers
8k views

When to use @ in an \if statement

I am new to LaTeX and so this question might come across as rather basic. It might also reflect my biases/assumptions from my C/C++ programming days. I was seeing the code of the 'exam' class and ...
24
votes
1answer
1k views

What is an \if?

I'm reading TeX by Topic, but in little chunks (rather than from first page to last) and just read the stuff on conditionals. I want to be sure that I understand what's going on when TeX starts ...
21
votes
2answers
3k views

What does \begingroup\expandafter…\endgroup do?

I often see code of the following form in package implementations (this example is from the LaTeX3 sources): \begingroup\expandafter\expandafter\expandafter\endgroup \expandafter\ifx\csname ...
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 ...
18
votes
5answers
1k views

Combining \ifxetex and \ifluatex with the logical OR operation

I want to write in the preamble of a LaTeX document code that should be take into account by different compilers when the document is typeset. There are fragments that should be used: only by ...
16
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4answers
2k 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 ...
26
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4answers
2k views

Test success of write18

For the new version of my package and class standalone I like to call external programs: further (pdf)latex runs to optionally compile included standalone files, and to convert the resulting PDF to ...
20
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3answers
5k views

What is the difference between \ifx\somecommand\undefined and \ifdefined\somecommand\else?

What is the difference between \ifx\cyrdash\undefined and \ifdefined\cyrdash\else? \cyrdash is any macro.
18
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5answers
6k views

new command with cases / conditionals / 'if… then's

Suppose I want to define a command, say, \tree with, say, two arguments. I would like \tree to do different things depending on what my first argument is. For example, if #1 = a, then return ...
12
votes
5answers
2k views

Teach me how to use \loop…\repeat constructs, etc

The following code snippet is a part of the solution given here: \def\IncludeOutput#1{ \parskip=2mm \def\examplename{#1} \pdfximage{\Directory/\examplename.pdf}% ...
12
votes
3answers
1k views

Choosing styles conditionally in TikZ

I want to create a series of images that visualise a recursion tree as walked on by an algorithm. That means that different styles are applied to nodes depending on the step the algorithm is in, such ...
17
votes
6answers
2k views

Checking if a number is a multiple of 4

Using etoolbox, ifthen, or another form of conditional checking, how can I check if a value is a multiple of 4? E.g. if the number is 4, 8, 12, 16, etc., then it returns "true".
17
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2answers
2k views

Doing something only when the draft option is on?

I would like to do some stuff that is only enabled when the draft option is given in \documentclass[draft]{article}. How would I go about doing this?
14
votes
2answers
1k 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, ...
13
votes
4answers
393 views

How do you test whether a known key value has been set in pgfkeys

Using the .code handler to my keys and a private macro, I can easily test whether a key has been set when using pgfkeys. For example: \documentclass{article} \newcounter{mytestenvcounter} ...
12
votes
2answers
570 views

How to detect if option provided via \tikzset

I would like to be able to detect if a particular option has been provided via a \tikzset and issue a message based on that. The MWE yields: But once the conditional works (just a comment for ...
12
votes
1answer
553 views

Biblatex: Print ISBN only if DOI is not defined

I have a large set of references and I in most cases do have either ISBN DOI DOI and ISBN I'd like to setup a filter that prints the ISBN only when the DOI does not exist. How can I set up a ...
8
votes
3answers
252 views

Detecting which version of the LaTeX format is in use

ltxcmds provides \ltx@ifpackagelater, \ltx@ifclasslater, \ltx@iffilelater and there is \@ifpackagelater - but is there any "if TeX later" or some other way to (automatically) get the used TeX version ...
23
votes
6answers
7k views

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 ...
19
votes
2answers
2k views

Difference between \newbool and \newtoggle from etoolbox package

Paul Gaborit's answer to How to detect if option provided via \tikzset uses \newbool to define a new boolean \booltrue to set a boolean, and \ifbool to perform a conditional operation all from ...
14
votes
1answer
457 views

Create Two PDF versions of Classroom slides from Single LaTeX file: Teacher and Student

Is there a way to create a single document that will process a LaTeX file in two different ways (different preambles) and produce two different outputs. Specifically, I want to produce a set of ...
11
votes
1answer
598 views

Require a certain (or later) version of a package?

Is there a way to enforce that a certain version, or a later version, of a package is loaded when building the document? I've found that compiling a document on another platform, where the package ...
9
votes
2answers
664 views

Expand command read from file

I have a file, that contains a list of latex commands each command per line. Now I want to read this file line per line and execute/expand the macros automatically. I tried the following but this only ...
8
votes
2answers
413 views

Custom ToC — Put vspace only below chapters that have sections in them

I’m using the titletoc package in the book class. Currently, my chapter entries are configured like this (I left out the unimportant parameters for simplicity): \titlecontents{chapter}[0pc] ...
7
votes
2answers
219 views

How can I write a conditional coloring command that distinguishes variables within sectioning commands vs those within the body text?

Question Is it possible to write a conditional statement for commands that change them based on where they appear in the document? Example Situation When command appears in the body, it should be ...
7
votes
2answers
202 views

How to use the total page count in a conditional expression?

I would like to have different footer or page style depending on whether the document has one or more pages. I am not very experienced with TeX programming, so the answers about "Comparing an argument ...
4
votes
3answers
703 views

Create odd-numbered answers, or all answers

I'm starting with a clean slate creating a solutions manual. I would like the ability, by setting a switch, to produce only the solutions for the odd-numbered problems, or those for all problems, in ...
22
votes
2answers
476 views

Show footnotes on odd pages only

I'm writing my thesis using the scrbook-class. Is it possible to display footnotes only on the odd (right) pages? This should mean that \footnote{something} should be collected on even pages and ...
12
votes
4answers
2k views

How to make a “condition” in a macro?

I would like to make a macro with two parameters which return a text. For instance, I want \M{1}{5} to return [1,5], and \M{2}{2} to return [2] (because the two arguments are the same). So I need to ...