Minus signs vanish with listings and breqn - any solutions?

Question

When using listings and breqn, the minus signs (or dashes, according to the unix.SX site then there's some controversy about which it is) disappear from code listing. Here's an example:

\documentclass{article}
\pagestyle{empty}
\usepackage{breqn}
\usepackage{listings}

\begin{document}


\lstset{language=Perl}
\begin{lstlisting}
#! /usr/bin/perl -w

if ($ARGV[0] =~ /^-/) {
    print "Option given";
}
\end{lstlisting}
\end{document}

with result:

Changing the order of package loading doesn't help. breqn does warn that it might break other packages, but it would be really useful to have both working. If it helps, the code listings are in appendices so happen after the equations which breqn is meant to help with so I can happily reset anything that got changed.

Answer 1

Your problem comes from the fact that \lstlisting likes to typeset a hypen-minus as $-$, and the the breqn package plays around with math so much. In particular, it sets the mathcode of the minus to "8000, which makes it active and seems to break things.

\documentclass{article}
\pagestyle{empty}
\mathchardef\hyphenmathcode=\mathcode`\-
\usepackage{breqn}
\usepackage{listings}

\let\origlstlisting=\lstlisting
\let\endoriglstlisting=\endlstlisting
\renewenvironment{lstlisting}
    {\mathcode`\-=\hyphenmathcode
     \everymath{}\mathsurround=0pt\origlstlisting}
    {\endoriglstlisting}

\begin{document}

\lstset{language=Perl}
\everymath{}
\begin{lstlisting}
#! /usr/bin/perl -w

if ($ARGV[0] =~ /^-/) {
    print "Option given";
}
\end{lstlisting}
\end{document}

(The \everymath{}\mathsurround is not necessary for this, but it should be there for good measure.)

Edit: Added the mathcode bit. I'll say more on this edit in the comments.

Answer 2

By default listings uses a math minus here and this clashes with breqn. You can change the symbol listings uses for the hyphen. For example this uses \textminus and will work also with breqn:

\documentclass{article}
\usepackage{listings}
\usepackage{breqn}

\begin{document}


\lstinline +ABC-ABC+ 

\makeatletter
\lst@CCPutMacro
    \lst@ProcessOther {"2D}{%
      \lst@ttfamily
         {\textminus}% used with ttfamily 
         \textminus}% used with other fonts
    \@empty\z@\@empty
\makeatother

\lstinline +ABC-ABC+

\lstset{basicstyle=\ttfamily}
\lstinline +ABC-ABC+

\end{document}

Answer 3

Here is a solution:

\documentclass{tufte-book}
\pagestyle{empty}
\usepackage{listings}
\usepackage{breqn}
\begin{document}

\normalfont

\makeatletter
\texttt{\meaning\lst@InputCatcodes\relax}
\makeatother

\lstset{language=Perl,escapeinside={(*@}{@*)}}
\begin{lstlisting}
#! /usr/bin/perl -w

if ($ARGV[0] =~ /^(*@-@*)/) {
    print "Option given";
}
\end{lstlisting}

\end{document}

It is really a font problem. The - sign in your font is an active character in listings. (See the meaning). If you escape it though it gets the right catcode and the error disappears. You escape using funny eyes:) (*@ @*) and you can insert anything you want. Perhaps someone else can come with an easier solution as I guess it is a hassle to have to escape the sign always.

I use MikTeX for compiling.

Edit

Another hack would be to define a new environment using the listings lstnewenvironment command to protect the definitions from other packages:

\lstnewenvironment{perl}[1][]
  {\lstset{language=Perl}\lstset{%
   #1
}}
{}

This also worked,

Use: \begin{perl}...\end{perl}

This solution is very similar to that given by Harald.

Answer 4

Any minus operator (-) I had in my code sample under lstlisting was not showing up. I would get an "Undefined control sequence. n--" error.

For whatever reason, this fixed it (it'll shows a big dash but that'll do it for a quick solution):

1- Adding the package minted (without using it):

\usepackage{minted}

2- Invoking LaTeX with the -shell-escape flag at each build.

Following the steps mentioned in this answer by hpesoj626:

In TeXstudio

Options > Configure TeXStudio > Build

in the User Commands box, click +Add button and add a name for your command in the first cell, say pdflatex -shell-escape and the command pdflatex -synctex=1 -interaction=nonstopmode --shell-escape %.tex in the second cell.

You can then see the command listed in the menu

Tools > User

Click on the command to run.

When I ran my code the minuses in the lstlisting sections showed up.