Split command output by odd/evens

Question

I have a document which looks like this, with a custom question command:

\documentclass[11pt]{article}

\newcommand\question[2]{\setcounter{qnum}{#1}\vspace{.25in}\hrule\textbf{#1:} \textit{#2}\vspace{.5em}\hrule\vspace{.10in}}
\newcounter{qnum}

\begin{document}
\question{1}{Prompt 1}

Answer 1

\question{2}{Prompt 2}

Answer 2

\question{3}{Prompt 3}

Answer 3

\end{document}

This may be beyond the scope of Latex, but is it possible to output the odd questions and their answers on one page (questions 1,3,5,..) and then have a pagebreak followed by the even questions and answers (questions 2,4,6,...)? I realize I could manually do this, but the questions have somewhat of a sequential nature (2 helps you answer 3) and typing them up in order is helpful to me. I wasn't able to find a similar question elsewhere.

You could try to use a if clause (like if the pagenumber is even do this if not that this …). — current_user, Sep 04 '18 at 17:10
@current_user Thanks, using "conditional" helped me search better. I'm looking at this and will get back. — Almacomet, Sep 04 '18 at 17:16
Do you have to use this format or are you open to different ways of setting this out? Also, how "complicated" can the prompts and answers be? — , Sep 04 '18 at 17:18
Does any of your code rely on category code changes (so do you use \verb or a verbatim like environment -- this includes listings)? Would it be ok for you to use an environment for input (I guess that the answers should be moved, too)? — Skillmon, Sep 04 '18 at 17:24
@Andrew The template is from here. I am rather fond of the look, but I see the answers package can do what I ask, if I concede the stylistic part. This is for math based homework, so answers/prompts may have inline equations, equations, proof environments, etc. There may occasionally be tables in either, but I can concede this. — Almacomet, Sep 04 '18 at 17:37
@Skillmon I may use a verbatim like environment occasionally, but it would be rare enough that if I am giving that up, it is okay. — Almacomet, Sep 04 '18 at 17:38

egreg · Accepted Answer · 2018-09-04T20:05:12.057

Here's the idea: you input the answer together with the question, saving it in a token register that can be delivered when you wish.

\documentclass[11pt]{article}

\newcommand\question[3]{%
  \par\vspace{.25in}\hrule\nopagebreak\vspace{.5em}
  \textbf{#1:} \textit{#2}\par\nopagebreak\vspace{.5em}
  \hrule\vspace{.10in}%
  \ifodd#1\relax
    \global\oddanswers=\expandafter{\the\oddanswers\answer{#1}{#3}}%
  \else
    \global\evenanswers=\expandafter{\the\evenanswers\answer{#1}{#3}}%
  \fi
}
\newtoks\oddanswers
\newtoks\evenanswers
\newcommand{\answer}[2]{%
  \par\noindent Answer to #1: #2\par
}
\newcommand{\printoddanswers}{\the\oddanswers}
\newcommand{\printevenanswers}{\the\evenanswers}

\begin{document}

\question{1}{Compute $1+1$}{$2$}
\question{2}{Compute $1+2$}{$3$}
\question{3}{Compute $1+3$}{$4$}
\question{4}{Compute $1+4$}{$5$}
\question{5}{Compute $1+5$}{$6$}

\section{Answers to odd numbered exercises}
\printoddanswers

\section{Answers to even numbered exercises}
\printevenanswers


\end{document}

The requested variant:

\documentclass[11pt]{article}

\newcommand\question[3]{%
  \ifodd#1\relax
    \global\oddquestions=\expandafter{%
      \the\oddquestions
      \problem{#1}{#2}%
      \answer{#1}{#3}%
    }%
  \else
    \global\evenquestions=\expandafter{%
      \the\evenquestions
      \problem{#1}{#2}%
      \answer{#1}{#3}%
    }%
  \fi
}
\newtoks\oddquestions
\newtoks\evenquestions

\newcommand{\problem}[2]{%
  \par\vspace{.25in}\hrule\nopagebreak\vspace{.5em}
  \textbf{#1:} \textit{#2}\par\nopagebreak\vspace{.5em}
  \hrule\vspace{.10in}%
}
\newcommand{\answer}[2]{%
  \par\noindent #2\par
}
\newcommand{\printoddquestions}{\the\oddquestions}
\newcommand{\printevenquestions}{\the\evenquestions}

\begin{document}

\question{1}{Compute $1+1$}{$2$}
\question{2}{Compute $1+2$}{$3$}
\question{3}{Compute $1+3$}{$4$}
\question{4}{Compute $1+4$}{$5$}
\question{5}{Compute $1+5$}{$6$}

\section{Odd numbered exercises}
\printoddquestions

\section{Even numbered exercises}
\printevenquestions


\end{document}

Thank you, that's very close. I wanted it to look more like this, sorry if that was unclear. I changed your answer command to remedy this, would it be appropriate for me to edit your post? — Almacomet, Sep 04 '18 at 18:19

score 1 · Answer 2 · 2018-09-05T05:36:56.477

Here is an expl3 variant that puts the problems into "even" and "odd" sequences and then prints them using command \evenquestions and \oddquestions, respectively. I have put the answers into environments as from the OP they can be relatively complicated.

Here's the output:

You can of course put the odd and even numbered questions on separate pages by putting something like \newpage in between the \oddquestions and \evenquestions commands.

Here is the code:

\documentclass{article}
\usepackage{expl3}
\usepackage{environ}

\ExplSyntaxOn
\newcommand\Question[2]{%
   \par\vspace{.25in}\hrule\vspace{0.5em}
   \noindent\textbf{#1:}~\textit{#2}\par
   \vspace{.5em}\hrule\vspace{.10in}
}
\seq_new:N \g_even_questions_seq
\seq_new:N \g_odd_questions_seq
\cs_new:Npn \add_to_sequence #1 #2 #3 #4 {
  \seq_gput_right:Nn #1 { \Question{#2} {#3} }
  \seq_gput_right:No #1 { #4 }
}
\NewEnviron{question}[2]{
  \int_if_odd:nTF {#1}
    { \add_to_sequence \g_odd_questions_seq {#1}{#2}{\BODY}}
    { \add_to_sequence \g_even_questions_seq {#1}{#2}{\BODY}}
}

\newcommand\oddquestions{
  \section{Odd~numbered~questions}
  \seq_map_inline:Nn \g_odd_questions_seq {##1}
}

\newcommand\evenquestions{
  \section{Even~numbered~questions}
  \seq_map_inline:Nn \g_even_questions_seq {##1}
}

\ExplSyntaxOff

\begin{document}

  \begin{question}{1}{Prompt 1}
    Answer 1
  \end{question}

  \begin{question}{2}{Prompt 2}
    Answer 2
  \end{question}

  \begin{question}{3}{Prompt 3}
    Answer 3
  \end{question}

  % now print the odd and even questions

  \oddquestions

  %\newpage

  \evenquestions

\end{document}

If all question numbers will appear (in the sense that if question k+1 appears then question k>0 also appears), then I would omit the first argument to the question environment and instead automatically insert it using a counter.

Edit

Rather using sequences I realised that it is better to use token lists. The following code does it this way, with identical output. For good measure, I have automated the question numbers:

\documentclass{article}
\usepackage{expl3}
\usepackage{environ}

\ExplSyntaxOn
\newcommand\Question[2]{%
   \par\vspace{.25in}\hrule\vspace{0.5em}
   \noindent\textbf{#1:}~\textit{#2}\par
   \vspace{.5em}\hrule\vspace{.10in}
}
\int_new:N \g_question_int
\tl_new:N \g_even_questions_tl
\tl_new:N \g_odd_questions_tl
\cs_new:Npn \add_to_questions #1 #2 #3 {
  \tl_gput_right:Nn #1 { \Question{\int_eval:n {\g_question_int}} {#2} }
  \tl_gput_right:No #1 { #3 }
}
\cs_generate_variant:Nn \int_if_odd:nTF {NTF}
\NewEnviron{question}[1]{
  \int_gincr:N \g_question_int
  \int_if_odd:NTF \g_question_int
    { \add_to_questions \g_odd_questions_tl  {#1} {\BODY} }
    { \add_to_questions \g_even_questions_tl {#1} {\BODY} }
}

\newcommand\oddquestions{
  \section{Odd~numbered~questions}
  \tl_use:N \g_odd_questions_tl
}

\newcommand\evenquestions{
  \section{Even~numbered~questions}
  \tl_use:N \g_even_questions_tl
}

\ExplSyntaxOff

\begin{document}

  \begin{question}{Prompt 1}
    Answer 1
  \end{question}

  \begin{question}{Prompt 2}
    Answer 2
  \end{question}

  \begin{question}{Prompt 3}
    Answer 3
  \end{question}

  % now print the odd and even questions

  \oddquestions

  %\newpage

  \evenquestions

\end{document}

Split command output by odd/evens

2 Answers2