[Tex/LaTex] How to ‘\input’ a file without getting the implicit newline

external filesinput

Intro

I'm working on a lightweight package that allows you to put any content (typically LaTeX code) in an environment, then use that content multiple times, each time scanned separately, so you can use it both as verbatim output and interpreted as LaTeX.

Its main purpose is to typeset LaTeX code and its 'result' side-by-side; useful for documenting TeX packages without having to copy/paste code. But it has other purposes as well.

After experimenting with \scantokens until I gave up in tears, I arrived at the filecontents environment, which almost solved my problem singlehandedly!

The Problem

The problem is, when reintroducing filecontented code through \input, LaTeX adds an implicit newline at the end, which translates to whitespace that I can't seem to get rid of.

I've seen many semi-related questions floating around, with answers employing techniques like:

reading a file line-by-line,
using \everyeof in some clever way,
playing with \endlinechar or
using packages such as catchfile

but none of them provides a clear answer to the following question:

The Question

How can I \input a file without getting the implicit newline?

Minimal Working Example

\documentclass[margin=1mm]{standalone}

\usepackage{filecontents}

\begin{filecontents*}{tmp.tex}
    \LaTeX{}\end{filecontents*}

\begin{document}
    \fbox{\input{tmp.tex}}
\end{document}

enter image description here

Note the extra whitespace to the right of the box.

Note also that I'm definitely not adding any explicit whitespace. Even a manually produced file (so, not using filecontents) with no newlines at all exhibits the same problem.

Best Answer

The following requires a different command, say \minput:

\documentclass[margin=1mm,varwidth]{standalone}

\usepackage{filecontents}

\newcommand\minput[1]{%
  \input{#1}%
  \ifhmode\ifnum\lastnodetype=11 \unskip\fi\fi}

\begin{filecontents*}{tmp.tex}
\LaTeX{}
\end{filecontents*}
\begin{filecontents*}{tmp2.tex}
\LaTeX
\end{filecontents*}
\begin{filecontents*}{tmp3.tex}
\LaTeX\hspace{2em}
\end{filecontents*}

\begin{document}
\fbox{\input{tmp.tex}} \fbox{\minput{tmp.tex}}

\minput{tmp}Nospace \minput{tmp} Space

\minput{tmp2} Space

\minput{tmp3}Nospace

\LaTeX\hspace{2em}Nospace
\end{document}

This will fail if the input file ends with something like \hskip 2pt, but I believe one can ignore such cases.

enter image description here

Related Solutions

[Tex/LaTex] Input file folder

The following is written to accord to Mac OS Xs' FHS implementation. This is principally valid for any UNIX-like OS. Pdflatex allows you to specify complete paths:

\input{/Users/user_name/some/path}

Under Unix-Like systems you may even use shell(bash) variables in you paths:

\input{$HOME/some/path}

or common abbreviations

\intput{\string~/some/path}

(note: using \string here to tell latex to pass the character to shell instead of taking the "meaning")

Of course you may also specify relative paths. This means of course you need to know what your active path is. For pdflatex this is most commonly the path (or directory) were yout main document lies (which is given pdflatex as an argument).

\input{some_file}

This will tell pdflatex to use some_file which is located in the active dir. (If not an error will be raised.)

\input{./some_file}

Will do exactly the same, while

\input{../some_file}

will tell pdflatex to use some_file which lies in the parent folder (one level above.)

So one might ask why? Well under common OSs like UNIX or Windows the dot representations are in charge, so that . represents the current/active folder and .. the parent. Therefore ../../ will represent a folder two levels above (the parent of the parent). This is possible, since the directory tree only knows one parent a a certain level. So 'going up' is all the same on any level.