在 itemize 或 enumerate 环境中计数项目

Question

有没有办法获取枚举中出现的项目数？我的目的是当我在列表中的任何位置添加新项目时自动更新该数字，因此像这样的东西将是理想的：

Here are the \numitems{mylist} points I wanted to address:
\begin{itemize}\label{mylist}
    \item important issue;
    \item another important issue;
    \item oh, and yet another critical thing.
\end{itemize}

Answer 1

itemize不使用计数器（带有\refstepcounter)）——那么\label是无用的（并且如果它应该使用，它必须在该last项目之后，而不是在第一个之前。

我对itemize环境进行了一些修补，并添加了一个新计数器，每次\item使用时都会重置并步进。

\getrefnumber{...}从包中使用refcount以获取可扩展的数字。

\documentclass{article}


\usepackage{xpatch}

\usepackage{refcount}


\newcommand{\numitems}[1]{\getrefnumber{#1}}
\newcounter{itemcntr}

\AtBeginEnvironment{itemize}{%
\setcounter{itemcntr}{0}%
\xapptocmd{\item}{\refstepcounter{itemcntr}}{}{}%
}

\begin{document}


Here are the \numitems{mylist} points I wanted to address:
\begin{itemize}
    \item important issue;
    \item another important issue;
    \item oh, and yet another critical thing. \label{mylist}
\end{itemize}


Here are the \numitems{otherlist} points I wanted to address:
\begin{itemize}
    \item important issue;
    \item another important issue;
    \item almost forgotten stuff;
    \item oh, and yet another critical thing. \label{otherlist}
\end{itemize}



\end{document}

Answer 2

下面允许enumitem与 的交互countlist，也许还有更简单的界面：您指定一个countlist具有强制参数的环境，该参数将引用列表。还允许使用可选参数，该参数以典型方式\label传递给环境。enumerateenumitem

refcount提供参考的数字显示，尽管在这种情况下实际上不需要。

\documentclass{article}

\usepackage{enumitem,refcount}

\newcounter{countlist}

\makeatletter
\newenvironment{countlist}[2][]
  {\begin{enumerate}[#1]
     \setcounter{countlist}{0}%
     \def\countname{#2}%
     \let\olditem\item
     \renewcommand{\item}{\stepcounter{countlist}\olditem}}
  {  \renewcommand{\@currentlabel}{\arabic{countlist}}%
     \label{\countname}%
   \end{enumerate}}
\makeatother

\newcommand{\numitems}[1]{\getrefnumber{#1}}
% Alternatively...
%\newcommand{\numitems}[1]{\ref{#1}}

\begin{document}

Here are the \numitems{mylist} points I wanted to address:
\begin{countlist}{mylist}
  \item important issue;
  \item another important issue;
  \item oh, and yet another critical thing.
\end{countlist}

Here are the \numitems{otherlist} points I wanted to address:
\begin{countlist}[label={(\Alph*)}]{otherlist}
  \item important issue;
  \item[(b*)] another important issue;
  \item almost forgotten stuff;
  \item oh, and yet another critical thing.
\end{countlist}

\end{document}

如果您想要itemize列表具有 -like 的感觉，可以使用 的默认label={\textbullet}可选参数enumerate。

Answer 3

一些有创意的用法enumitem：

\documentclass{article}
\usepackage{enumitem}

\newcounter{itemcount}
\newenvironment{countitemize}[1]
 {\def\countitemizelabel{#1}%
  \setcounter{itemcount}{0}%
  \itemize[label=\stepcounter{itemcount}\textbullet]}
 {\addtocounter{itemcount}{-1}%
  \refstepcounter{itemcount}\label{\countitemizelabel}%
  \enditemize}

\begin{document}

Here are the \ref{mylist} points I wanted to address:
\begin{countitemize}{mylist}
\item important issue;

\item another important issue;

\item oh, and yet another critical thing.
\end{countitemize}

Let's check the formatting
\begin{itemize}
\item important issue;

\item another important issue;

\item oh, and yet another critical thing.
\end{itemize}

\end{document}

如果你想计算每一个的实例\item，那么你可以做

\documentclass{article}
\usepackage{etoolbox}

\newcounter{itemcount}
\newenvironment{countitemize}[1]
 {\def\countitemizelabel{#1}%
  \setcounter{itemcount}{0}%
  \preto\item{\stepcounter{itemcount}}
  \itemize}
 {\addtocounter{itemcount}{-1}%
  \refstepcounter{itemcount}\label{\countitemizelabel}%
  \enditemize}

\begin{document}

Here are the \ref{mylist} points I wanted to address:
\begin{countitemize}{mylist}
\item important issue;

\item another important issue;

\item oh, and yet another critical thing.
\end{countitemize}

Let's check the formatting
\begin{itemize}
\item important issue;

\item another important issue;

\item oh, and yet another critical thing.
\end{itemize}

\end{document}

但是，在嵌套环境中计数仍会继续。如果您需要，可以解决这个问题。

我提供countitemize最多 3 级嵌套。

\documentclass{article}
\usepackage{etoolbox}

\newcounter{itemcounti}
\newcounter{itemcountii}
\newcounter{itemcountiii}

\makeatletter
\newif\ifnestedcountitemize
\newenvironment{countitemize}[1]
 {\ifnestedcountitemize\else
    \preto\item{\stepcounter{itemcount\romannumeral\@listdepth}}%
    \nestedcountitemizetrue
  \fi
  \begin{itemize}%
  \def\countitemizelabel{#1}%
  \setcounter{itemcount\romannumeral\@listdepth}{0}}
 {\addtocounter{itemcount\romannumeral\@listdepth}{-1}%
  \refstepcounter{itemcount\romannumeral\@listdepth}\label{\countitemizelabel}%
  \end{itemize}}
\makeatother

\begin{document}

Here are the \ref{mylist} points I wanted to address:
\begin{countitemize}{mylist}
\item important issue;

\item another important issue;

\item oh, and yet another critical thing.
\begin{countitemize}{innerlist}
  \item With a nested list

  \item again
\end{countitemize}
\end{countitemize}

There is an inner list with \ref{innerlist} items.

\end{document}