![定义新命令时出错](https://linux22.com/image/385445/%E5%AE%9A%E4%B9%89%E6%96%B0%E5%91%BD%E4%BB%A4%E6%97%B6%E5%87%BA%E9%94%99.png)
我正在尝试在我的 Latex 文件中定义一个新命令,如下所示
\newcommand{\newchunk}[1][2]{\section{#2}\label{sec:#1}\quad}
但是在 Latex 编译后我得到以下错误
ERROR: Illegal parameter number in definition of \\newchunk.
--- TeX said ---
<to be read again>
2
l.58 ...nk}[1][2]{\section{#2}\label{sec:#1}\quad}
--- HELP ---
This is probably caused by a \newcommand, \renewcommand,
\newenvironment, or \renewenvironment command in which a # is used
incorrectly. A # character, except as part of the command name \#,
can be used only to indicate an argument parameter, as in #2, which
denotes the second argument. This error is also caused by nesting one
of the above four commands inside another, or by putting a parameter
like #2 in the last argument of a \newenvironment or \renewenvironment
command.
我们不是用来#2
指代第二个参数吗?我哪里错了?
答案1
\newcommand{\newchunk}[1][2]{\section{#2}\label{sec:#1}\quad}
定义一个命令\newchunk
,使其具有一个可选参数,该参数的默认值为2
。看起来你正在定义一个可以接受包含 的可选参数的命令\label
。这里有一个建议:
\documentclass{article}
\newcommand{\newchunk}[2][]{%
\section{#2}%
% https://tex.stackexchange.com/q/53068/5764
\if\relax\detokenize{#1}\relax\else
\label{sec:#1}%
\fi
}
\begin{document}
\newchunk{First}
See section~\ref{sec:second}.
\newchunk[second]{Second}
\end{document}
上面的代码\newchunk
有两个参数,第一个是可选的标签字符串,用于\label
。将检查用户是否提供了任何内容。如果提供了内容,则将其用作\label
,否则不\label
发出任何内容。第二个参数是必需的,用作\section
标题。
答案2
\newcommand{<command>}[<number of arguments>]{<what the command does>}
的第二个参数\newcommand
需要命令所采用的参数数量。因此,您需要执行
\newcommand{\newchunk}[2]{\section{#2}\label{sec:#1}\quad}