Reference table rows by automatic counter

Question

Problem

I have defined an environment to automatically number example sentences throughout my document. It uses the tabular environment and automatically numbers the first column of each row using a custom counter. I have reasons for not using lists or the theorem counter.

I want to label and reference a table row so that the number associated with the row is displayed. Using \label and \ref does not work. Is there some way to feed a function two args, a key and the current value of my counter, and later use the key to recall the other arg? Or is there another way to do what I want? Not breaking the labels and references for the rest of the document is ideal but not necessary.

(Non-)Working Example

\documentclass{article}
\usepackage{array} %don't know why this is needed; get csname error otherwise

% automatically number examples throughout document
\newcounter{exno}
\newenvironment{examples}
{
\begin{flushleft}
\begin{tabular}{>{(\stepcounter{exno}\theexno)}rl}
}
{
\end{tabular}
\end{flushleft}
}

\begin{document}

\section{Foo}
Here are some numbered example sentences.
\begin{examples}
  &Content of row 1 \label{row1} \\
  &Content of row 2 \label{row2}
\end{examples}
Now I want to get a 1 here: \ref{row1}. I want to get a 2 here: \ref{row2}.

\end{document}

Answer 1

In order for you to reference the counter like that you need to use \refstepcounter. This steps the counter, as well as telling LaTeX to use the supplied counter for the following reference.

Then you need to replace the \label's. They need to address directly to the counter. Therefore your example would be:

\documentclass{article}
\usepackage{array} %don't know why this is needed; get csname error otherwise

% automatically number examples throughout document
\newcounter{exno}
\newenvironment{examples}
{
\begin{flushleft}
\begin{tabular}{>{(\refstepcounter{exno}\theexno)}rl}
}
{
\end{tabular}
\end{flushleft}
}

\begin{document}

\section{Foo}
Here are some numbered example sentences.
\begin{examples}
  \label{row1} &Content of row 1 \\
  \label{row2} &Content of row 2
\end{examples}
Now I want to get a 1 here: \ref{row1}. I want to get a 2 here: \ref{row2}.

\end{document}

This will produce:

Added: This also works by linking to the row by loading hyperref package.

Answer 2

This is very similar to zeroth's solution, but if one put the label definition in the \newenvironment it is more comfortable. So you don't need to create a label for each row manually.

\documentclass{article}
\usepackage{array} %don't know why this is needed; get csname error otherwise

% automatically number examples throughout document
\newcounter{exno}
\newenvironment{examples}
{
\begin{flushleft}
\begin{tabular}{>{(\refstepcounter{exno}\theexno\label{row:\theexno}) }rl}
}
{
\end{tabular}
\end{flushleft}
}

\begin{document}

\section{Foo}
Here are some numbered example sentences.
\begin{examples}
&Content of row 1 \\
&Content of row 2
\end{examples}
Now I want to get a 1 here: \ref{row:1}. I want to get a 2 here: \ref{row:2}.

\end{document}

Edit: After zeroth's comment I edit my post to show how it works with more than one example. Just use an other counter for the example-environments. Or give each environment an unique name (as argument) and use it instead of the example-counter. Than it is possible to reference to the example and to the table rows. I think a lot of LaTeX environments works this way.

\documentclass{article}
\usepackage{array} %don't know why this is needed; get csname error otherwise

% automatically number examples throughout document

%link the RowNumberCounter to the ExampleNumberCounter
\newcounter{ExampleNumber}
\newcounter{RowNumber}[ExampleNumber]

\newenvironment{examples}
{
\stepcounter{ExampleNumber}
%
\begin{flushleft}%
\begin{tabular}{>{%
(\refstepcounter{RowNumber}\theRowNumber%
\label{Example:\theExampleNumber:Row:\theRowNumber}) }rl}%
}
{%
\end{tabular}%
\end{flushleft}%
}%

\begin{document}

\section{Foo}
Here are some numbered example sentences.
\begin{examples}
&Content of row 1 \\
&Content of row 2
\end{examples}
Now I want to get a 1 here: \ref{Example:1:Row:1}. I want to get a 2 here: \ref{Example:1:Row:2}.

\begin{examples}
&Content of row 1 \\
&Content of row 2\\
&Content of row 3 \\
&Content of row 4
\end{examples}
Now I want to get a 1 here: \ref{Example:2:Row:1}. I want to get a 2 here: \ref{Example:2:Row:2}.
Now I want to get a 3 here: \ref{Example:2:Row:3}. I want to get a 4 here: \ref{Example:2:Row:4}.
\end{document}

Answer 3

I have following additional requirements

• named labels (and not autogeneratd ones) for each row, because I sometimes exchange rows.
• allow first column to be centered.
• cleveref support.
• similar appearance as the algorithmic environment.

I couldn't get cleveref to work, therefore, I'm using autoref.

Therefore, I came up with that solution:

\documentclass{article}

\usepackage{array}
\usepackage{hyperref}

\newcounter{rowcount}
\setcounter{rowcount}{0}
\newcommand{\rowcountautorefname}{Line}

\begin{document}

\begin{tabular}{@{{\makebox[1.3em][r]{\footnotesize\the\numexpr\value{rowcount}+1\relax:}}\hspace*{1.5\tabcolsep}}>{\refstepcounter{rowcount}}c}
line 1 \\
long line 2 \\
\label{line3} longer line 3
\end{tabular}

\autoref{line3} shows the longest line.

\end{document}

Based on https://tex.stackexchange.com/a/58139/9075 and https://tex.stackexchange.com/a/54892/9075.