在问卷的宏中包含标签

Question

我正在用 LaTeX 写一份问卷，想做一个问题的宏。我想要的一个功能是使用标签交叉引用问题（例如，以防您想跳过某个问题）。以下是我目前拥有的 MWE：

\documentclass{article}
\usepackage{tabu,textcomp,amsmath,longtable}
\usepackage[left=2cm, right=2cm, top=2cm]{geometry}

\newcounter{qnumber}
\setcounter{qnumber}{0}
\stepcounter{qnumber}

\newcommand{\question}[3]{
\hfill \theqnumber\hfill\hfill & #1 & #2 & #3\stepcounter{qnumber}\\ \hline
}

\begin{document}

\begin{longtabu} to \textwidth {|c|X|X|X|}
\hline
\textbf{Sl.} & 
\textbf{Question text} & 
\textbf{Instructions for enumerator (not to be read out)} &
\textbf{Response options} 
\\ \hline

\question{What is your age?}{Enter age in years}{18--99}    
\question{Do you rent your house?}{}{1. Yes; 2. No}    

\end{longtabu}
\end{document}

我希望有另一组花括号，\question可以为问题提供标签，然后允许交叉引用问题编号。例如：

\question{Do you rent your house}{lab:rent}
\question{If you answered "Yes" in question \ref{lab:rent}, how much do you pay per month} 

我该如何调整这条\newcommand线路才能让它工作呢？

Answer 1

例如，您可以使用一个可选参数，\question如果不为空，则该参数将成为标签：

\documentclass{article}
\usepackage{tabu,textcomp,amsmath,longtable}
\usepackage[left=2cm, right=2cm, top=2cm]{geometry}

\newcounter{qnumber}
\setcounter{qnumber}{0}

\newcommand{\question}[4][]{%
  \refstepcounter{qnumber}%
  \if\relax\detokenize{#1}\relax
  \else
    \label{#1}%
  \fi
  \hfill\theqnumber\hfill\hfill & #2 & #3 & #4\\ \hline
}

\begin{document}

\begin{longtabu} to \textwidth {|c|X|X|X|}
\hline
\textbf{Sl.} & 
\textbf{Question text} & 
\textbf{Instructions for enumerator (not to be read out)} &
\textbf{Response options}
\\ \hline

\question{What is your age?}{Enter age in years}{18--99}
\question[lab:rent]{Do you rent your house?}{}{1. Yes; 2. No}
\question{If you answered "Yes" in question \ref{lab:rent}, how much do you pay per month}{}{}

\end{longtabu}
\end{document}