`\unexpand\expandafter` 添加空格：如何在文件末尾附加文本

Question

我想将代码附加到包含乳胶代码的文件中...所以我尝试了这里提出的解决方案，但不幸的是，当文件中有反斜杠时它会失败：如何以“追加”模式打开文件？

所以我尝试用它来调整它\unexpand\expandafter{\filecontent}#2，但是它在“命令”后面添加了空格，这真的很烦人：

梅威瑟：

\documentclass{article}
\usepackage{verbatim}

\usepackage{catchfile}

\newwrite\appendwrite
\newcommand*\appendtofile[2]{%
    \begingroup
    \IfFileExists{#1}%
      {\CatchFileDef{\filecontent}{#1}{\endlinechar=`^^J\catcode\endlinechar=12\relax}}% keep existing end-of-lines
      {\let\filecontent\empty}%
    \immediate\openout\appendwrite=#1\relax
    \immediate\write\appendwrite{\unexpanded\expandafter{\filecontent}#2}%
    \immediate\closeout\appendwrite
    \endgroup
}

\newcounter{mycounter}
\begin{document}

\appendtofile{\jobname.test}{\string\Mycode\themycounter}

First, everything is good:\\
\verbatiminput{\jobname.test}

\appendtofile{\jobname.test}{Second line}

Second, see how the spaces are added:\\
\verbatiminput{\jobname.test}

\end{document}

Answer 1

你可以逐字逐句地读回文件\

\documentclass{article}
\usepackage{verbatim}

\usepackage{catchfile}

\newwrite\appendwrite
\newcommand*\appendtofile[2]{%
    \begingroup
    \IfFileExists{#1}%
      {\CatchFileDef{\filecontent}{#1}{\catcode`\\=12 \endlinechar=`^^J\catcode\endlinechar=12\relax}}% keep existing end-of-lines
      {\let\filecontent\empty}%
    \immediate\openout\appendwrite=#1\relax
    \immediate\write\appendwrite{\detokenize\expandafter{\filecontent}#2}%
    \immediate\closeout\appendwrite
    \endgroup
}

\newcounter{mycounter}
\begin{document}

\appendtofile{\jobname.test}{\string\Mycode\themycounter}

First, everything is good:\\
\verbatiminput{\jobname.test}

\appendtofile{\jobname.test}{Second line}

Second, see how the spaces are added:\\
\verbatiminput{\jobname.test}

\end{document}