Conditionals within captions

Question

I have defined a conditional using the ifthen package as:

\newcommand{\Switch}[1] { \ifthenelse{\equal{#1}{1}}{Test1}{Test2} }

Running this command works without problem. However, if I try to place it within a Figure Caption, it produces an error (i.e., \Switch{1} and \caption{Example text} work fine, but \caption{\Switch{1}} does not).

Is this expected behavior? How do I work around it to produce a conditional caption?

score 6 · Answer 1 · answered Jan 03 '11 at 15:24

6

The \ifthenelse command appears to be fragile? \caption{\protect\Switch{1}} works.

answered Jan 03 '11 at 15:24

Harald Hanche-Olsen

15,968

score 3 · Answer 2 · answered Jan 03 '11 at 16:09

3

As a modern alternative, you can use the commands from the etoolbox package:

\newcommand*{\Switch}[1]{\ifnumequal{#1}{1}{Test1}{Test2}}

Or the xparse package:

\ExplSyntaxOn
\NewDocumentCommand \Switch { m } {
  \int_compare:nNnTF { #1 } = { \c_one } {
    Test1
  } {
    Test2
  }
}
\ExplSyntaxOff

answered Jan 03 '11 at 16:09

Philipp

17,641

2

You don't like \int_compare:nTF { #1=1 }? No need for using the constant here (in fact, we shouldn't be promoting their use much, really). – Will Robertson Jan 03 '11 at 16:31

score 0 · Answer 3 · answered Mar 13 '21 at 15:19

The other solutions work, just adding this one for completeness. It also has the advantage of not needing \protect.

Declare your command as robust with:

\DeclareRobustCommand{\Switch}[1] { \ifthenelse{\equal{#1}{1}}{Test1}{Test2} }

You can now use \caption{\Switch{1}} just fine.

See this question for details about the difference between \newcommand and \DeclareRobustCommand.

Conditionals within captions

3 Answers3