Adding Labels and Referencing Modified Listing Environments

Question

I want to label and reference the modified listing environments namely Matlab Code and Matlab Output. However, when I add the \label command and try to reference the labelled modified listing environments, I get ?? which is something I do not desire. Below is my MWE which is a solution to my problem by @Tom found at Incorrect classification of multiple listings entries:

\documentclass[openany]{book}
\usepackage{regexpatch}
\usepackage[nottoc]{tocbibind}
\usepackage{caption}
\usepackage{listings}
\usepackage{hyperref}
% --------------------------------------- C++
\newcommand{\lstlistmatlaboutputname}{List of Matlab Output}
\newcommand{\lstlistofmatlaboutput}{\begingroup
    \tocfile{\lstlistmatlaboutputname}{loc}
    \endgroup}
% --------------------------------------- R
\newcommand{\lstlistmatlabcodename}{List of Matlab Code}
\newcommand{\lstlistofmatlabcode}{\begingroup
    \tocfile{\lstlistmatlabcodename}{lor}
    \endgroup}
% --------------------------------------- Pseudocode
\newcommand{\lstlistpseudocodename}{List of Pseudocode}
\newcommand{\lstlistofpseudocode}{\begingroup
    \tocfile{\lstlistpseudocodename}{lop}
    \endgroup}
\makeatletter
\lstnewenvironment{matlaboutput}[1][]{%
    \renewcommand{\lstlistingname}{Matlab Output}%
    \renewcommand{\ext@lstlisting}{loc}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{loc}{}{}% use this with earlier version caption package
    \lstset{language=C++,#1}}%
{}
\lstnewenvironment{matlabcode}[1][]{%
    \renewcommand{\lstlistingname}{Matlab Code}%
    \renewcommand{\ext@lstlisting}{lor}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{lor}{}{}% use this with earlier version caption package
    \lstset{language=R,#1}}
{}
\lstnewenvironment{pseudocode}[1][]{%
    \renewcommand{\lstlistingname}{Pseudocode}%
    \renewcommand{\ext@lstlisting}{lop}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{lop}{}{}% use this with earlier version caption package
    \lstset{basicstyle=\ttfamily,#1}}%
{}
\makeatother
\begin{document}
\lstlistofmatlaboutput
\lstlistofmatlabcode    
\lstlistofpseudocode

\chapter{Listings}
\begin{matlaboutput}[caption = {Some class definition}]\label{outp:1}
    % example matlab output
\end{matlaboutput}

\begin{matlabcode}[caption = {For educational purposes}]\label{code:1}
    % example matlab code 1
\end{matlabcode}


See Output \ref{outp:1} and Code \ref{code:1} above.
\end{document}

score 2 · Accepted Answer · answered Feb 26 '23 at 02:28

You should use the label argument to the listings environment, instead of trying to set a \label inside it. The later can be done, but it has to be properly escaped, and is usually to refer to the line number rather than the whole environment.

\documentclass[openany]{book}
\usepackage{regexpatch}
\usepackage[nottoc]{tocbibind}
\usepackage{caption}
\usepackage{listings}
\usepackage{hyperref}
% --------------------------------------- C++
\newcommand{\lstlistmatlaboutputname}{List of Matlab Output}
\newcommand{\lstlistofmatlaboutput}{\begingroup
    \tocfile{\lstlistmatlaboutputname}{loc}
    \endgroup}
% --------------------------------------- R
\newcommand{\lstlistmatlabcodename}{List of Matlab Code}
\newcommand{\lstlistofmatlabcode}{\begingroup
    \tocfile{\lstlistmatlabcodename}{lor}
    \endgroup}
% --------------------------------------- Pseudocode
\newcommand{\lstlistpseudocodename}{List of Pseudocode}
\newcommand{\lstlistofpseudocode}{\begingroup
    \tocfile{\lstlistpseudocodename}{lop}
    \endgroup}
\makeatletter
\lstnewenvironment{matlaboutput}[1][]{%
    \renewcommand{\lstlistingname}{Matlab Output}%
    \renewcommand{\ext@lstlisting}{loc}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{loc}{}{}% use this with earlier version caption package
    \lstset{language=C++,#1}}%
{}
\lstnewenvironment{matlabcode}[1][]{%
    \renewcommand{\lstlistingname}{Matlab Code}%
    \renewcommand{\ext@lstlisting}{lor}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{lor}{}{}% use this with earlier version caption package
    \lstset{language=R,#1}}
{}
\lstnewenvironment{pseudocode}[1][]{%
    \renewcommand{\lstlistingname}{Pseudocode}%
    \renewcommand{\ext@lstlisting}{lop}%
    %\xpatchcmd*{\caption@ORI@lst@MakeCaption}{lol}{lop}{}{}% use this with earlier version caption package
    \lstset{basicstyle=\ttfamily,#1}}%
{}
\makeatother
\begin{document}
\lstlistofmatlaboutput
\lstlistofmatlabcode
\lstlistofpseudocode

\chapter{Listings}
\begin{matlaboutput}[caption = {Some class definition},label={outp:1}]
    % example matlab output
\end{matlaboutput}

\begin{matlabcode}[caption = {For educational purposes},label={code:1}]
    % example matlab code 1
\end{matlabcode}


See Output \ref{outp:1} and Code \ref{code:1} above.
\end{document}

When I type the command \ref, I get a list of all my labels in my document. However, the labels assigned to the modified listings are not appearing. What could be the cause? — itc, Feb 26 '23 at 02:55
@itc A \ref produces a reference to a given label, not a list of them. I'm not sure I understand what you mean. Either way, what you asked was about the undefined labels, and that's what I answered about. — gusbrs, Feb 26 '23 at 03:23
If one is using texstudio, typing the command \ref will produce a dropdown list of all the labels in the document. That is what I mean. The solution you provided is working except that the labellings for matlab code and output are not appearing in that dropdown list. — itc, Feb 26 '23 at 03:27
Ah, that's a texstudio issue, perhaps it does not recognize a label if it is set as the argument of a custom environment, which is actually to be expected. There might be ways to configure it, but I don't know. Anyway, there's no point in setting "a label which texstudio recognizes" if it is wrong on the LaTeX side of things, is there? — gusbrs, Feb 26 '23 at 03:34

Adding Labels and Referencing Modified Listing Environments

1 Answers1