循环遍历可选参数

Question

我想使用\foo带有可选参数的命令来执行并打印根据传递的数字迭代的计数器值。

因此，例如，\foo[5]应该逐一踩下计数器 5 次。

（！）请注意，它与 不同\stepcounter{}{5}。

平均能量损失

\documentclass{report}

\newcounter{mycount}
\setcounter{mycount}{0}
\newcommand{\foo}{\stepcounter{mycount}counter is \textbf{\themycount}}

\begin{document}
first use: \foo

second use: \foo

now using with option to iterate: \foo[2]

\medskip

\textit{desired output from line above should be:}

\medskip

now using with option to iterate: counter is \textbf{3,4}

\end{document}

Answer 1

expl3只需几行即可。

\documentclass{report}
\usepackage{xparse}

\newcounter{mycount}
\setcounter{mycount}{0}

\ExplSyntaxOn
\NewDocumentCommand{\foo}{O{1}}
 {
  \int_compare:nT { #1 > 0 }
   {
    \int_compare:nTF { #1 = 1 } {counter~is} {counters~are}~
    \stepcounter{mycount}
    \textbf{\themycount}
    \prg_replicate:nn { #1 - 1 } {,\stepcounter{mycount}\textbf{\themycount}}
   }
 }
\ExplSyntaxOff

\begin{document}
first use: \foo

second use: \foo

now using with option to iterate: \foo[2]

now using with option to iterate: counters are \textbf{3,4}

\foo[5]

\end{document}

诀窍是进行第一次迭代，然后再次继续，先添加逗号。

如果传递的数字为零或更小，则什么也不会发生。

Answer 2

multido以下是包含、xparse和 的短代码etoolbox：

\documentclass{report}
\usepackage{multido}
\usepackage{xparse, etoolbox}
\newcounter{mycount}
\setcounter{mycount}{0}
\NewDocumentCommand{\foo}{O{1}}{counter is \multido{\i=1+1}{#1}{\stepcounter{mycount}\textbf{\themycount}\ifnumless{\multidocount}{#1}{,\,}{.}}}

\begin{document}

first use: \foo

second use: \foo

now using with option to iterate: \foo[5]

\end{document}

Answer 3

这是一种使用的方法multidofor 循环和延迟分隔符定义：

\documentclass{article}

\usepackage{multido}

\newcounter{mycount}

\newcommand{\foo}[1][1]{%
  counter%
  \ifnum#1>1\relax s are\else \space is\fi
  \space
  % https://tex.stackexchange.com/a/89187/5764
  \def\itemdelim{\unskip\space\def\itemdelim{,\space}}% Item delimiter delayed by one cycle
  {\bfseries\multido{\i=1+1}{#1}{\itemdelim \stepcounter{mycount}\themycount}}%
}

\begin{document}

first use: \foo

second use: \foo

now using with option to iterate: \foo[2]

\medskip

\textit{desired output from line above should be:}

\medskip

now using with option to iterate: counters are \textbf{3, 4}

\end{document}

Answer 4

更多一些代码，但没有额外的软件包：

\documentclass{report}

\newcounter{mycount}
\setcounter{mycount}{0}

\newcommand\Exchange[2]{#2#1}%
\newcommand{\foo}[1][1]{\fooloop{#1}{}{counter value is}}
\makeatletter
\newcommand{\fooloop}[3]{%
  \ifnum#1>0 \stepcounter{mycount}\fi
  \ifnum#1>1 \expandafter\@firstoftwo\else\expandafter\@secondoftwo\fi
  {% 
    \begingroup
    \protected@edef\@tempa{\themycount}%
    \c@mycount=#1\relax
    \advance\c@mycount by -1\relax
    \expandafter\endgroup
    \expandafter\fooloop\expandafter
    {\number\expandafter\c@mycount\expandafter}\expandafter
    {\romannumeral0\expandafter\Exchange\expandafter{\@tempa}{ #2}, }%
    {counter values are}%
  }{%
    #3 \textbf{#2\themycount}%
  }%
}%
\makeatother

\begin{document}
first use: \foo

second use: \foo

now using with option to iterate: \foo[4]

\medskip

\textit{desired output from line above should be:}

\medskip

now using with option to iterate: counter values are \textbf{3, 4, 5, 6}

\medskip

now using with option to iterate 0 times---counter is unchanged and displayed: \foo[0]

\medskip

now using with option to iterate -1 times---counter is unchanged and displayed: \foo[-1]

\end{document}