How can I get my cross-reference refer to my custom counter and not the section number where the label is

Question

I created my own counter and an environment named problem. The counter increments on the level of a chapter, not section. When I label, e.g. \label{prb:3} and refer to it later in the text by \ref{prb:3}, instead of inserting the true problem number that was linked to that label, section number within which the problem lies gets inserted. That obiously makes a serious trouble. Although I checked some similar previous questions on this problem, I have not recognized something that helps my case. For example, using Problem~\hyperref[prb:3]{prb:3} prints Problem prb:3, while it should, for example, be Problem 5-8.

Essentially, my \label and \ref command should link to my problem number and not to the section number within which the problem lies.

I believe there are more than enough LaTeX experts that can help me set up and resolve this case, preferably without complicated definitions.

Here is some MWE:

\documentclass[a4paper,11pt, oneside]{book}
\usepackage[utf8]{inputenc}
%%% my custom counter `problem` and the environment, which increments on the chapter level
\newcounter{problem}
\newenvironment{problem}{
\vspace{10pt}\noindent\stepcounter{problem}\\
{\bf\thechapter-\theproblem}\hspace{10pt}
}{}
\begin{document}
\chapter{First Chapter}
\section{Section 11}
    \begin{problem}
            Problem~1-1. \label{prb 11}  % Problem 1-1
    \end{problem}

\section{Section 12}
    \begin{problem}
            Problem 1-2. \label{prb 12}  % Problem 1-2
    \end{problem}
    \begin{problem}
            Problem 1-3. \label{prb 13} \\  % Problem 1-3
    \end{problem}


\noindent Referring to Problem~1-3 by \ref{prb 13} incorrectly refers to Problem~1.2 because Problem~1-3 is in Section~\ref{prb 13} (that is: Section 1.1). \ \
\setcounter{problem}{0}
\chapter{Second Chapter}
\section{Section 21}
    \begin{problem}
        Problem 2-1. \label{prb 21}  % Problem 2-1
    \end{problem}
    \begin{problem}
        Problem 2-2. \label{prb 22}  % Problem 2-2
    \end{problem}
    \begin{problem}
        Problem 2-3. \label{prb 23} \\  % Problem 2-3
    \end{problem}


\noindent Now referring to Problem~2-3 by \ref{prb 23} erroneously prints as Problem~2.1 because Problem~2-3 is within Section~\ref{prb 23} (that is: Section 2.1). \ \
So, not only is the number incorrect, but also the format. Instead of having chapter-problem# format, it has section# format. \
The question is: how can I make the \verb|\label| and \verb|\ref| not refer to a Section number, but to the Problem number within a particular chapter?
\end{document}

Answer 1

There are at least three problems, or issues, with your problem-related code [pun intended].

• The most serious one is that you're using \stepcounter instead of \refstepcounter to increment the counter called problem. The \label-\ref mechanism relies (with a few exceptions) on LaTeX associating the argument of \label with the counter that was most recently incremented via a \refstepcounter directive. \stepcounter doesn't cut it; that is why the \ref directives keep pointing to section numbers since, as you may have guessed by now, the section counter is incremented via a \refstepcounter directive whenever a \section command is executed.

• Right now, you have to run \setcounter{problem}{0} at the start of each chapter. If you replace \newcounter{problem} with \newcounter{problem}[chapter], LaTeX resets the problem counter to 0 automatically each time a \chapter directive occurs.

• Since you wish to display the "number" of the problem as "ChapterNum-ProblemNum", you might as well run

  \renewcommand\theproblem{\arabic{chapter}-\arabic{problem}}
  

  in the preamble

---

\documentclass[oneside]{book}
%% \usepackage[utf8]{inputenc} that's the default nowadays
\newcounter{problem}[chapter]
\renewcommand\theproblem{\arabic{chapter}-\arabic{problem}}
\newenvironment{problem}{%
  \par\vspace{10pt}\noindent\refstepcounter{problem}% % note "\refstepcounter"
  \textbf{\theproblem}\hspace{10pt}}%
  {\par}
\usepackage[colorlinks]{hyperref} % optional
\begin{document}
\chapter{First Chapter}
\section{Section A}
        \begin{problem}
            Problem~1-1. \label{prb 11}  % Problem 1-1
        \end{problem}
\section{Section B}
        \begin{problem}
            Problem 1-2. \label{prb 12}  % Problem 1-2
        \end{problem}
        \begin{problem}
            Problem 1-3. \label{prb 13}  % Problem 1-3
        \end{problem}
\bigskip\noindent Now cross-referencing Problem~1-3 as \ref{prb 13}, \emph{not} as [section] 1.2.
\chapter{Second Chapter}
\section{Section C}
        \begin{problem}
            Problem 2-1. \label{prb 21}  % Problem 2-1
        \end{problem}
        \begin{problem}
            Problem 2-2. \label{prb 22}  % Problem 2-2
        \end{problem}
        \begin{problem}
            Problem 2-3. \label{prb 23}  % Problem 2-3
        \end{problem}
\bigskip\noindent Now cross-referencing Problem~2-3 as \ref{prb 23}, \emph{not} as [section] 2.1.
\end{document}

---

In response to @Mico, this is the new MWE explaining how \ref works when referring to \label that was defined in the main file as opposed to the \label defined in the outer file.

\documentclass[oneside]{book}
\newcounter{problem}[chapter]
\renewcommand\theproblem{\arabic{chapter}-\arabic{problem}}
\newenvironment{problem}{%
  \par\vspace{10pt}\noindent\refstepcounter{problem}%
  \textbf{\theproblem}\hspace{10pt}}%
  {\par}
%\renewcommand\theproblem{\arabic{chapter}-\arabic{problem}}
\usepackage[colorlinks]{hyperref} % optional
\begin{document}
\chapter{Chapter Title}
\section{Section Title}
        \begin{problem}
            Problem 1-1. \label{prb_11}
        \end{problem}
        \begin{problem}
            Problem 1-2. \label{prb_12}
        \end{problem}
    \input{prb_13}


\bigskip\noindent When the \verb|\label| is used within the main file, the cross-referencing works well and \verb|\ref{prb_11}| gives \ref{prb_11} and \verb|\ref{prb_12}| gives \ref{prb_12}. Correct!
\medskip\noindent In contrast, when the label is defined within the outer file named \verb|prb_13| and included using the \verb|\input| command, the cross-referencing does not work well and \verb|\ref{prb_13}| gives \ref{prb_13}, which is not the problem number, but the section number.
\end{document}

Answer 2

Edit: See the comment and the answer of David Carlisle and Mico respectively (and "respect-worthy")

You can do it with custom labels like here:

https://tex.stackexchange.com/a/18192/120578

\documentclass[a4paper,11pt, oneside]{book}
\usepackage[utf8]{inputenc}
%%% my custom counter `problem` and the environment, which increments on the chapter level
\newcounter{problem}
\newenvironment{problem}{
\vspace{10pt}\noindent\stepcounter{problem}\\
{\bf\thechapter-\theproblem}\hspace{10pt}
}{}
\makeatletter
\newcommand{\clabel}[1]{%
\protected@write @auxout {}{\string \newlabel {#1}{{\thechapter-\theproblem}{}}}}
\makeatother
\begin{document}
\chapter{First Chapter}
\section{Section 11}
    \begin{problem}
            Problem~1-1. \clabel{prb11}  % Problem 1-1
    \end{problem}

\section{Section 12}
    \begin{problem}
            Problem 1-2. \clabel{prb12}  % Problem 1-2
    \end{problem}
    \begin{problem}
            Problem 1-3. \clabel{prb13}  % Problem 1-3
    \end{problem}


\noindent Referring to Problem~1-3 by \ref{prb13} correctly refers to Problem~1.2 [because Problem~1-3 is in Section~\ref{prb13} (that is: Section 1.1). ]
\setcounter{problem}{0}
\chapter{Second Chapter}
\section{Section 21}
    \begin{problem}
        Problem 2-1. \clabel{prb21}  % Problem 2-1
    \end{problem}
    \begin{problem}
        Problem 2-2. \clabel{prb22}  % Problem 2-2
    \end{problem}
    \begin{problem}
        Problem 2-3. \clabel{prb23} \\  % Problem 2-3
    \end{problem}


\noindent Now referring to Problem~2-3 by \ref{prb23}  [prints as Problem~2.1 because Problem~2-3 is within Section~\ref{prb23} (that is: Section 2.1). ]
So, not only is the number incorrect, but also the format. Instead of having chapter-problem# format, it has section# format.
The question is: how can I make the \verb|\label| and \verb|\ref| not refer to a Section number, but to the Problem number within a particular chapter?
\end{document}