Does anyone know an easy way to check if an item is a member in a comma-separated list?
Something like this would be excellent:
\ifmember{elem1}{elem1,elem2,elem3}{true}{false}
The above would expand to true since elem1 is in the list.
Thanks
Asked
Active
Viewed 598 times
2
Edd Barrett
- 357
- 1
- 2
- 11
-
How is the list done? – Jan 11 '16 at 14:24
-
6Does this help you? Package to test whether a string is in a list – Alenanno Jan 11 '16 at 14:25
-
@Alenanno looks promising, will try it out. – Edd Barrett Jan 11 '16 at 14:26
-
The xstring method works great. – Edd Barrett Jan 12 '16 at 11:59
2 Answers
7
LaTeX has such a test built in already, so you just need to define your requested syntax:
\documentclass{article}
\makeatletter
\newcommand\ifmember[2]{%
\in@{#1}{#2}%
\ifin@
\expandafter\@firstoftwo
\else
\expandafter\@secondoftwo
\fi
}
\makeatother
\begin{document}
\ifmember{elem1}{elem1,elem2,elem3}{true}{false}
\ifmember{elem4}{elem1,elem2,elem3}{true}{false}
\end{document}
David Carlisle
- 757,742
-
2actually The question is a duplicate (and Heiko's answer there covers this) I'll vote to close. – David Carlisle Jan 11 '16 at 15:53
1
Here's a quick expl3 (well, xparse method, for checking whether the second argument is in the list. However, the clist-variable would be in a command macro, usually,otherwise you would know if it is in the list.
\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
\NewDocumentCommand{\IsMember}{mm+m+m}{%
\clist_set:Nx \l_tmpa_clist {#1}
\clist_if_in:NnTF \l_tmpa_clist {#2} {#3} {#4}
}
\ExplSyntaxOff
\newcommand{\foo}{%
elem1,elem2,elem3%
}
\begin{document}
\IsMember{\foo}{elem1}{true}{false}
\IsMember{\foo}{elem5}{true}{false}
\end{document}