Link from label to ref and back?

Question

I would like that the objects marked with label clickable so that when you click on it moves you to the relative \ref object and the other way around.

How should I do it?

\documentclass{article}
\begin{document}
\begin{enumerate}
  \item test\label{l1}
\end{enumerate}


   \pagebreak

   test2\ref{l1}
\end{document}

Answer 1

If you don't use multiple \refs per \label you could use the following:

\documentclass{article}
\usepackage{hyperref}

\newcommand{\mylabel}[2]{%
  \hyperref[#1]{#2}\label{back:#1}
}
\newcommand{\myref}[2]{%
  \hyperref[back:#1]{#2}\label{#1}
}

\begin{document}
  \begin{enumerate}
    \item \mylabel{l1}{test}
  \end{enumerate}

  \pagebreak

  \myref{l1}{test2}
\end{document}

Another solution would be to pack \hyperlink and \hypertarget in a macro:

\documentclass{article}
\usepackage{hyperref}

\newcommand{\mylabel}[2]{%
  \hyperlink{back:#1}{\hypertarget{#1}{#2}}
}
\newcommand{\myref}[2]{%
  \hyperlink{#1}{\hypertarget{back:#1}{#2}}
}

\begin{document}
  \begin{enumerate}
    \item \mylabel{l1}{test}
  \end{enumerate}

  \pagebreak

  \myref{l1}{test2}
\end{document}

Answer 2

I understand your setup to be as follows: You have numbered answers in one part of the document, you have answers somewhere else in the document, and you would like to provide two-way hyperlinks between Question 1 and Answer to Question 1, Question 2 and Answer to Question 2, etc.

• If you have numbered questions and increment the question-related counter using \refstepcounter, you can use \ref in the answer to create a link to the numbered question. If hyperref is loaded, the \ref will be resolved into a hyperlink automatically. The only tricky part is to create a hyperlink from the question to the answer; you can't use \ref as in all likelihood there's no (independent) counter associated with the answers. Fortunately, hyperref provides the \hyperlink/\hypertarget pair of macros for just this case.

• In the example below, I've set up an environment called question that takes three arguments: The question's title, the text of the \label that's associated with the question, and the name of the hypertarget associated with the answer. The third argument is used in the environment's \hyperlink instruction.

• The corresponding answer entry takes two arguments: the argument of the \label macro of the associated question, and the name of the answer's hypertarget. (Note that arguments 2 and 3 of the question should be the same as the arguments 1 and 2 of the associated answer.) The second argument is used in the environment's \hypertarget instruction.

\documentclass{article}
\usepackage{amssymb}  % for \Box macro
\usepackage[colorlinks=true,
            linkcolor=red]
           {hyperref}
\usepackage[textheight=3cm]
           {geometry} %% just for this example

\newcounter{quest}
\newenvironment{question}[3]{%
   \refstepcounter{quest} \label{#2}
   \par\bigskip\noindent
   \textbf{Question \thequest: #1?}
   \par\medskip

   For an answer, click here: \hyperlink{#3}{$\Box$}}{\par\bigskip}

\newenvironment{answer}[2]{%
   \par\bigskip\noindent%
   \hypertarget{#2}{\textbf{Answer to Question \ref{#1}}}%
   \par\medskip}{\par\bigskip}

\begin{document}

\begin{question}{What's the meaning of life}%
                {quest:life}{ans:life}
\end{question}

\begin{question}{What is Pythagoras' Theorem}%
                {quest:pyth}{ans:pyth}
\end{question}

\newpage
\begin{answer}{quest:life}{ans:life}
Mumble, mumble, mumble \dots
\end{answer}

\begin{answer}{quest:pyth}{ans:pyth}
Mumble, mumble, mumble \dots
\end{answer}
\end{document}