¿Cómo puedo implementar lo siguiente en látex? Deseo tener una variable predefinida (en el preámbulo), llamémosla A.
Entonces deseo tener un comando como
\TwoTexts{Text1}{Text2}
eso se cumplirá de la siguiente manera: si A=1, entonces se mostrará Texto1, si A=2, entonces se mostrará Texto2.
¿Algunas ideas? ¡Gracias!
Respuesta1
Aquí hay una versión con una macro \Amacroo un contador llamado acntr. Personalmente prefiero la versión contraria ya que no implica una redefinición de \Amacrosi es necesario.
La prueba de 1o si no se realiza con\ifnum...\fi
Aquí supuse que cualquier valor que no sea 1se bifurcará a Text2.
\documentclass{article}
\newcommand{\Amacro}{1}
\newcommand{\TwoTexts}[2]{%
\ifnum\Amacro=1\relax%
#1%
\else
#2%
\fi
}
\newcounter{acntr}
\newcommand{\TwoTextsImproved}[2]{%
\ifnum\value{acntr}=1\relax
#1%
\else
#2%
\fi
}
\begin{document}
\setcounter{acntr}{1}
\TwoTexts{You should see this}{Nope, not this}
\renewcommand{\Amacro}{2}
\TwoTexts{You should see this}{Nope, this is it}
\TwoTextsImproved{You should see this}{Nope, not this}
\stepcounter{acntr}
\TwoTextsImproved{You should see this}{Nope, this is it}
\end{document}
Respuesta2
Para evitar problemas con el desequilibrio ... \if..Haría el truco en términos de / :\else\fi\Firstoftwo\Secondoftwo
\documentclass{article}
\newcommand\Firstoftwo[2]{#1}%
\newcommand\Secondoftwo[2]{#2}%
\newcommand\Amacro{1}%
\newcommand\setAmacro[1]{\renewcommand\Amacro{#1}}%
\newcommand{\TwoTexts}{%
\ifnum\Amacro>1 %
\expandafter\Secondoftwo
\else
\expandafter\Firstoftwo
\fi
}
\begin{document}
\setAmacro{-3}
\texttt{\string\Amacro} is \Amacro.\\
\TwoTexts{Text in case the value in \texttt{\string\Amacro} is smaller than 1 or equal to 1}%
{Text in case the value in \texttt{\string\Amacro} is larger than 1}%
\setAmacro{0}
\texttt{\string\Amacro} is \Amacro.\\
\TwoTexts{Text in case the value in \texttt{\string\Amacro} is smaller than 1 or equal to 1}%
{Text in case the value in \texttt{\string\Amacro} is larger than 1}%
\setAmacro{1}
\texttt{\string\Amacro} is \Amacro.\\
\TwoTexts{Text in case the value in \texttt{\string\Amacro} is smaller than 1 or equal to 1}%
{Text in case the value in \texttt{\string\Amacro} is larger than 1}%
\setAmacro{2}
\texttt{\string\Amacro} is \Amacro.\\
\TwoTexts{Text in case the value in \texttt{\string\Amacro} is smaller than 1 or equal to 1}%
{Text in case the value in \texttt{\string\Amacro} is larger than 1}%
\setAmacro{17}
\texttt{\string\Amacro} is \Amacro.\\
\TwoTexts{Text in case the value in \texttt{\string\Amacro} is smaller than 1 or equal to 1}%
{Text in case the value in \texttt{\string\Amacro} is larger than 1}%
\end{document}
Por cierto: hace algunos años escribí una rutina \UD@KeepKthOfLArgumentsque le permite elegir un argumento arbitrario no delimitado entre una cantidad arbitraria de argumentos no delimitados que, debido a la recursividad, no está sujeto al límite de 9 argumentos generalmente impuesto en la macroprogramación de TeX. .
Puede usar esa rutina para crear otra rutina \choosetextque elija argumentos no delimitados que contengan frases de texto dependiendo del valor numérico contenido en alguna variable/marcador de posición/macro/ \countregistro/lo que sea.
\documentclass{article}
\makeatletter
%%=========================================================================
%% Paraphernalia:
%% \UD@firstoftwo, \UD@secondoftwo, \UD@PassFirstToSecond
%%.........................................................................
\newcommand\UD@firstoftwo[2]{#1}%
\newcommand\UD@secondoftwo[2]{#2}%
\newcommand\UD@PassFirstToSecond[2]{#2{#1}}%
%%-------------------------------------------------------------------------
%% Check whether argument is empty:
%%.........................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%% {<Tokens to be delivered in case that argument
%% which is to be checked is empty>}%
%% {<Tokens to be delivered in case that argument
%% which is to be checked is not empty>}%
%%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
%%
%% A concern in his posting is that the argument is hit with \string
%% after some expansions which in edge cases might result in unbalancing
%% surrounding \if..\fi-constructs if the macro is used inside of such
%% \if..\fi-constructs.
%%
%% That challenging concern sickened me. ;-)
%%
%% Therefore I decided to implerment a variant where this cannot happen
%% as expansion is forced by \romannumeral:
%%
%% After the first expansion-step, \string is not applied yet.
%% After the second expansion-step, any possibly disturbing remainders
%% are already removed due to \romannumeral-expansion.
%%
%% No eTeX- or whatsoever extensions. No \if.. .Only \romannumeral,
%% digit 0, space token for terminating \romannumeral-expansion,
%% \string, \expandafter, \UD@firstoftwo, \UD@secondoftwo, {, }.
%%
%% May 20, 2016
%%
%% Ulrich Diez (e-mail: [email protected])
%%
\newcommand\UD@CheckWhetherNull[1]{%
\romannumeral0\expandafter\UD@secondoftwo\string{\expandafter
\UD@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
\UD@secondoftwo\string}\expandafter\UD@firstoftwo\expandafter{\expandafter
\UD@secondoftwo\string}\expandafter\expandafter\UD@firstoftwo{ }{}%
\UD@secondoftwo}{\expandafter\expandafter\UD@firstoftwo{ }{}\UD@firstoftwo}%
}%
%%-------------------------------------------------------------------------
%% Keep only the K-th of L consecutive undelimited arguments.
%% ( IF K < 1 OR K > L just remove L consecutive undelimited arguments. )
%%.........................................................................
%% \UD@KeepKthOfLArguments{<integer number K>}%
%% {<integer number L>}%
%% {<Tokens to insert before K-th argument>}%
%% <L consecutive undelimited arguments>
%%
%% If K >= 1 and K <= L yields:
%% <Tokens to insert before K-th argument><K-th undelimited argument>
%% If K < 1 or K > L
%% (-> there is no K-th argument in the set
%% of <L consecutive undelimited arguments> )
%% yields:
%% <Tokens to insert before K-th argument>
%%
%% Examples:
%%
%% X\UD@KeepKthOfLArguments{3}{7}{<Tokens to insert>}{A}{B}{C}{D}{E}{F}{G}X
%% yields: X<Tokens to insert>CX
%%
%% X\UD@KeepKthOfLArguments{5}{2}{<Tokens to insert>}{A}{B}X
%% yields X<Tokens to insert>X
%%
%% X\UD@KeepKthOfLArguments{0}{2}{<Tokens to insert>}{A}{B}X
%% yields X<Tokens to insert>X
%%
%% X\romannumeral0%
%% \UD@KeepKthOfLArguments{3}{7}{ <Tokens to insert>}{A}{B}{C}{D}{E}{F}{G}X
%% yields: X\romannumeral0 <Tokens to insert>CX
%% yields: X<Tokens to insert>CX
%% In case of embedding the whole thing in other expansion-contexts,
%% you need to have "hit" \romannumeral by only one \expandafter-chain for
%% obtaining the result...
%%
%% January 17, 2005
%%
%% Ulrich Diez (e-mail: [email protected])
%%
\newcommand\UD@KeepKthOfLArguments[2]{%
\expandafter\UD@KeepKthOfLArgumentsA
\expandafter{\romannumeral\number\number#1 000\expandafter}%
\expandafter{\romannumeral\number\number#2 000}%
}%
\newcommand\UD@KeepKthOfLArgumentsA[3]{%
\UD@CheckWhetherNull{#1}{%
\UD@RemoveNArguments{#2}{#3}{}%
}{%
\expandafter\UD@PassFirstToSecond
\expandafter{%
\UD@firstoftwo{}#1}{\UD@KeepKthOfLArgumentsB{#1}{#2}}{#2}{#3}%
}%
}%
\newcommand\UD@KeepKthOfLArgumentsB[5]{%
\UD@CheckWhetherNull{#1}{%
\UD@RemoveNArguments{#3}{\UD@RemoveNArguments{#2}{#5}}{}%
}{%
\UD@CheckWhetherNull{#2}{%
\UD@RemoveNArguments{#4}{#5}{}%
}{%
\expandafter\UD@PassFirstToSecond
\expandafter{%
\UD@firstoftwo{}#2}{\expandafter\UD@KeepKthOfLArgumentsB
\expandafter{%
\UD@firstoftwo{}#1}}{#3}{#4}{#5}%
}%
}%
}%
\newcommand\UD@RemoveNArguments[3]{%
\UD@CheckWhetherNull{#1}{#2#3}{%
\UD@firstoftwo{%
\expandafter\UD@RemoveNArguments
\expandafter{\UD@firstoftwo{}#1}{#2}{#3}%
}%
}%
}%
%%-------------------------------------------------------------------------
%% A demo-routine:
%%
%% \choosetext{<number>}%
%% {<Text in case number < 1>}%
%% {<Text in case number = 1>}%
%% {<Text in case number = 2>}%
%% {<Text in case number = 3>}%
%% {<Text in case number = 4>}%
%% {<Text in case number = 5>}%
%% {<Text in case number = 6>}%
%% {<Text in case number = 7>}%
%% {<Text in case number = 8>}%
%% {<Text in case number = 9>}%
%% {<Text in case number = 10>}%
%% {<Text in case number = 11>}%
%% {<Text in case number = 12>}%
%% {<Text in case number = 13>}%
%% {<Text in case number = 14>}%
%% {<Text in case number > 14>}%
%%
%% The <number>-argument can hold anything that _expands_ to the components
%% of a quantity that is subsumable under the term <number> which is
%% explained in Donald E. Knuth's The TeXbook, Chapter 24: Summary of
%% Vertical Mode.
%%
%% Therefore <number> can as well be a macro-token expanding to a digit-
%% sequence, or a \the-call to a \count-register.
%%
%% January 24, 2017
%%
%% Ulrich Diez (e-mail: [email protected])
%%
%%.........................................................................
\newcommand\choosetext[1]{%
\romannumeral0%
\UD@KeepKthOfLArguments{\ifcase\expandafter\UD@firstoftwo
\expandafter{\number\ifnum#1<1 0\else#1\fi}{} %
1\or2\or3\or4\or5\or6\or7\or8\or
9\or10\or11\or12\or13\or14\or15\else16\fi}%
{16}%
{ }%
}%
%%-------------------------------------------------------------------------
%% A "variable" \Amacro and the routine \setAmacro for setting it's value.
%%.........................................................................
\newcommand\Amacro{1}%
\newcommand\setAmacro[1]{\renewcommand\Amacro{#1}}%
\makeatother
\begin{document}
The \verb|<number>|-argument of \verb|\choosetext| can hold anything that
expands to the components of a quantity that is subsumable under the term
\verb|<number>| which is explained in Donald E. Knuth's The TeXbook,
Chapter 24: Summary of Vertical Mode.
\bigskip
Thus the \verb|<number>|-argument of \verb|\choosetext| can hold a sequence
of digits, e.g., the digit \verb|5|:
\bigskip
\choosetext{5}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\bigskip
The \verb|<number>|-argument of \verb|\choosetext| can as well hold a
macro-token which serves as variable/placeholder for numerical values.
\bigskip
\setAmacro{17}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{15}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{14}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{13}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{12}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{11}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{10}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{9}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{8}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{7}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{6}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{5}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{4}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{3}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{2}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{1}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{0}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{-1}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\end{document}
Respuesta3
Como Atu"variable") es una constante, puedes definirla \TwoTextscon:
\newcommand\TwoTexts[2]{#1} % case A = 1
% \newcommand\TwoTexts[2]{#2} % case A = 2
Para elegir el valor de A, descomente la línea correcta.
Respuesta4
Acabo de mejorar mi \choosetextrutina dehttps://tex.stackexchange.com/a/350169/118714. Ahora puede especificar el límite inferior y el límite superior para el rango del número de variable. Por medio del paquete bigintcalc de Heiko Oberdiek, la rutina calculará la cantidad de argumentos no delimitados que se van a procesar y elegirá el argumento correcto automáticamente.
\documentclass{article}
\usepackage{bigintcalc}
\makeatletter
%%=========================================================================
%% Paraphernalia:
%% \UD@firstoftwo, \UD@secondoftwo, \UD@PassFirstToSecond
%%.........................................................................
\newcommand\UD@firstoftwo[2]{#1}%
\newcommand\UD@secondoftwo[2]{#2}%
\newcommand\UD@PassFirstToSecond[2]{#2{#1}}%
%%-------------------------------------------------------------------------
%% Check whether argument is empty:
%%.........................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%% {<Tokens to be delivered in case that argument
%% which is to be checked is empty>}%
%% {<Tokens to be delivered in case that argument
%% which is to be checked is not empty>}%
%%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
%%
%% A concern in his posting is that the argument is hit with \string
%% after some expansions which in edge cases might result in unbalancing
%% surrounding \if..\fi-constructs if the macro is used inside of such
%% \if..\fi-constructs.
%%
%% That challenging concern sickened me. ;-)
%%
%% Therefore I decided to implerment a variant where this cannot happen
%% as expansion is forced by \romannumeral:
%%
%% After the first expansion-step, \string is not applied yet.
%% After the second expansion-step, any possibly disturbing remainders
%% are already removed due to \romannumeral-expansion.
%%
%% No eTeX- or whatsoever extensions. No \if.. .Only \romannumeral,
%% digit 0, space token for terminating \romannumeral-expansion,
%% \string, \expandafter, \UD@firstoftwo, \UD@secondoftwo, {, }.
%%
%% May 20, 2016
%%
%% Ulrich Diez (e-mail: [email protected])
%%
\newcommand\UD@CheckWhetherNull[1]{%
\romannumeral0\expandafter\UD@secondoftwo\string{\expandafter
\UD@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
\UD@secondoftwo\string}\expandafter\UD@firstoftwo\expandafter{\expandafter
\UD@secondoftwo\string}\expandafter\expandafter\UD@firstoftwo{ }{}%
\UD@secondoftwo}{\expandafter\expandafter\UD@firstoftwo{ }{}\UD@firstoftwo}%
}%
%%-------------------------------------------------------------------------
%% Keep only the K-th of L consecutive undelimited arguments.
%% ( IF K < 1 OR K > L just remove L consecutive undelimited arguments. )
%%.........................................................................
%% \UD@KeepKthOfLArguments{<integer number K>}%
%% {<integer number L>}%
%% {<Tokens to insert before K-th argument>}%
%% <L consecutive undelimited arguments>
%%
%% If K >= 1 and K <= L yields:
%% <Tokens to insert before K-th argument><K-th undelimited argument>
%% If K < 1 or K > L
%% (-> there is no K-th argument in the set
%% of <L consecutive undelimited arguments> )
%% yields:
%% <Tokens to insert before K-th argument>
%%
%% Examples:
%%
%% X\UD@KeepKthOfLArguments{3}{7}{<Tokens to insert>}{A}{B}{C}{D}{E}{F}{G}X
%% yields: X<Tokens to insert>CX
%%
%% X\UD@KeepKthOfLArguments{5}{2}{<Tokens to insert>}{A}{B}X
%% yields X<Tokens to insert>X
%%
%% X\UD@KeepKthOfLArguments{0}{2}{<Tokens to insert>}{A}{B}X
%% yields X<Tokens to insert>X
%%
%% X\romannumeral0%
%% \UD@KeepKthOfLArguments{3}{7}{ <Tokens to insert>}{A}{B}{C}{D}{E}{F}{G}X
%% yields: X\romannumeral0 <Tokens to insert>CX
%% yields: X<Tokens to insert>CX
%% In case of embedding the whole thing in other expansion-contexts,
%% you need to have "hit" \romannumeral by only one \expandafter-chain for
%% obtaining the result...
%%
%% January 17, 2005
%%
%% Ulrich Diez (e-mail: [email protected])
%%
\newcommand\UD@KeepKthOfLArguments[2]{%
\expandafter\UD@KeepKthOfLArgumentsA
\expandafter{\romannumeral\number\number#1 000\expandafter}%
\expandafter{\romannumeral\number\number#2 000}%
}%
\newcommand\UD@KeepKthOfLArgumentsA[3]{%
\UD@CheckWhetherNull{#1}{%
\UD@RemoveNArguments{#2}{#3}{}%
}{%
\expandafter\UD@PassFirstToSecond
\expandafter{%
\UD@firstoftwo{}#1}{\UD@KeepKthOfLArgumentsB{#1}{#2}}{#2}{#3}%
}%
}%
\newcommand\UD@KeepKthOfLArgumentsB[5]{%
\UD@CheckWhetherNull{#1}{%
\UD@RemoveNArguments{#3}{\UD@RemoveNArguments{#2}{#5}}{}%
}{%
\UD@CheckWhetherNull{#2}{%
\UD@RemoveNArguments{#4}{#5}{}%
}{%
\expandafter\UD@PassFirstToSecond
\expandafter{%
\UD@firstoftwo{}#2}{\expandafter\UD@KeepKthOfLArgumentsB
\expandafter{%
\UD@firstoftwo{}#1}}{#3}{#4}{#5}%
}%
}%
}%
\newcommand\UD@RemoveNArguments[3]{%
\UD@CheckWhetherNull{#1}{#2#3}{%
\UD@firstoftwo{%
\expandafter\UD@RemoveNArguments
\expandafter{\UD@firstoftwo{}#1}{#2}{#3}%
}%
}%
}%
%%-------------------------------------------------------------------------
%% \UD@incrementloop{<lower bound>}%
%% {<upper bound>}%
%% {<count start>}%
%% {<tokens to prepend in front of each number except last number>}%
%% {<tokens to prepend in front of last number>}%
%% {<tokens to prepend at the begnning>}%
%% {<tokens to append at the end>}%
%%
%% Examples:
%% \UD@incrementloop{3}{7}{2}{<Before All>}{<Before Number>}{<Before Last Number>}{<After Last Numbe>r}
%%
%% -> The range 3..7 contains 7-3+1 consecutive integeral numbers/elements
%% = 5 consecutive integeral numbers/elements.
%% -> Gathering 5 consecutive integeral numbers/elements starting with
%% number/element 2 yields the numbers/elements 2,3,4,5,6.
%% (You can gather them by iteratively decrementing from 7-3=4 until
%% reaching -1 while within each iteration before reaching -1
%% "spitting out" a value and incrementing that value, starting
%% with value=2.)
%%
%% -> <Before All><Before Number>2<Before Number>3<Before Number>4<Before Number>5<Before Last Number>6<After Last Number>
%%
%% ,i.e., with
%% <Before All>=\ifcase[<number>] 1} and
%% <Before Number>=\or and
%% <Before Last Number>=\else and
%% <After Last Number>=\fi
%% yields:
%%
%% \UD@incrementloop{3}{7}{2}{\ifcase[<number>] 1}{\or}{\else}{\fi}
%% ->
%% \ifcase[<number>] 1\or2\or3\or4\or5\else6\fi
%%
\newcommand\UD@incrementloop[3]{%
\romannumeral0%
\expandafter\UD@PassFirstToSecond
\expandafter{\number#3}{%
\expandafter\expandafter\expandafter\UD@PassFirstToSecond
\expandafter\expandafter\expandafter{\bigintcalcSub{\number#2}{\number#1}}%
{\UD@@incrementloop}{}%
}%
}%
\newcommand\UD@@incrementloop[7]{%
\ifnum\bigintcalcCmp{0}{#1}=-1 %
\expandafter\UD@secondoftwo
\else
\expandafter\UD@firstoftwo
\fi
{%
\ifnum\bigintcalcCmp{0}{#1}=1 %
\expandafter\UD@secondoftwo
\else
\expandafter\UD@firstoftwo
\fi
{ #4#2#6#3#7}%
{ #4#2#7}%
}{%
\expandafter\expandafter\expandafter\UD@PassFirstToSecond
\expandafter\expandafter\expandafter{\bigintcalcInc{#3}}%
{\expandafter\expandafter\expandafter\UD@@incrementloop
\expandafter\expandafter\expandafter{\bigintcalcDec{#1}}%
{#2#5#3}}{#4}{#5}{#6}{#7}%
}%
}%
%%-------------------------------------------------------------------------
%% A demo-routine:
%%
%% \choosetext{<number from variable>}%
%% {<number denoting lower bound>}%
%% {<number denoting upper bound>}%
%% {<Text in case <number from variable> is smaller than <number denoting lower bound> >}%
%% {<Text in case <number from variable> = <number denoting lower bound> >}%
%% {<Text in case <number from variable> = <number denoting lower bound>+1 >}%
%% {<Text in case <number from variable> = <number denoting lower bound>+2 >}%
%% ...
%% {<Text in case <number from variable> = <number denoting lower bound>+K >
%% ...
%% {<Text in case <number from variable> = <number denoting upper bound>-2 >}%
%% {<Text in case <number from variable> = <number denoting upper bound>-1 >}%
%% {<Text in case <number from variable> = <number denoting upper bound> >}%
%% {<Text in case <number from variable> is larger than <number denoting upper bound> >}%
%%
%% The <number...>-arguments can hold anything that _expands_ to the components
%% of a quantity that is subsumable under the term <number> which is
%% explained in Donald E. Knuth's The TeXbook, Chapter 24: Summary of
%% Vertical Mode.
%%
%% Therefore the <number...>-arguments can as well be a macro-tokens expanding
%% to a digit-sequences, or \the-calls to \count-registers.
%%
%% Due to \romannumeral-expansion the result is delivered within two
%% expansion-steps.
%%
%% January 24, 2017
%%
%% Ulrich Diez (e-mail: [email protected])
%%
%%.........................................................................
\newcommand\choosetext[3]{%
\romannumeral0%
\UD@KeepKthOfLArguments{%
\UD@incrementloop{2}%
{\bigintcalcAdd{\bigintcalcSub{\number#3}{\number#2}}{3}}%
{2}%
{%
\ifcase\expandafter\UD@firstoftwo\expandafter{%
\number
\ifnum\bigintcalcCmp{%
\bigintcalcSub{\number#1}{\number#2}%
}{0}<0 %
\expandafter\UD@firstoftwo
\else
\expandafter\UD@secondoftwo
\fi
{0}{%
\bigintcalcAdd
{\bigintcalcSub{\number#1}{\number#2}}%
{1}%
}%
}{} 1%
}%
{\or}%
{\else}%
{\fi}%
}{%
\bigintcalcAdd{\bigintcalcSub{\number#3}{\number#2}}{3}%
}{ }%
}%
%%-------------------------------------------------------------------------
%% A "variable" \Amacro and the routine \setAmacro for setting it's value.
%%.........................................................................
\newcommand\Amacro{1}%
\newcommand\setAmacro[1]{\renewcommand\Amacro{#1}}%
\makeatother
\begin{document}
The \verb|<number>|-argument of \verb|\choosetext| can hold anything that
expands to the components of a quantity that is subsumable under the term
\verb|<number>| which is explained in Donald E. Knuth's The TeXbook,
Chapter 24: Summary of Vertical Mode.
\bigskip
Thus the \verb|<number>|-argument of \verb|\choosetext| can hold a sequence
of digits, e.g., the digit \verb|5|:
\bigskip
\choosetext{5}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\bigskip
The \verb|<number>|-argument of \verb|\choosetext| can as well hold a
macro-token which serves as variable/placeholder for numerical values.
\bigskip
\setAmacro{9}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{7}{12}%
{Text in case number is smaller than 7}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is larger than 12}%
\hrulefill
\setAmacro{9}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{4}{8}%
{Text in case number is smaller than 4}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is larger than 8}%
\hrulefill
\setAmacro{17}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{14}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{13}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{12}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{11}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{10}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{9}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{8}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{7}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{6}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{5}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{4}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{3}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{2}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{1}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{0}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\hrulefill
\setAmacro{-1}%
\verb|\Amacro| expands to the number \Amacro:
\choosetext{\Amacro}{1}{14}%
{Text in case number is smaller than 1}%
{Text in case number is 1}%
{Text in case number is 2}%
{Text in case number is 3}%
{Text in case number is 4}%
{Text in case number is 5}%
{Text in case number is 6}%
{Text in case number is 7}%
{Text in case number is 8}%
{Text in case number is 9}%
{Text in case number is 10}%
{Text in case number is 11}%
{Text in case number is 12}%
{Text in case number is 13}%
{Text in case number is 14}%
{Text in case number is larger than 14}%
\end{document}
