[Tex/LaTex] How to make figure and listing share their counter

Question

I'm using the "listings" package to write pieces of code (XML, RDF, Java, etc) and I want them to have the same counter of the Figure environment.

For example,

Listing 1: blablabla
Listing 2: blebleble
Figure 3: bliblibli
Listing 4: blobloblo
Figure 5: blublublu

The purpose of doing it is to change the "Listing" label to "Figure". But I need both environments to share the same counter. How I do it?

Thanks in advance.

Answer 1

You can make things so the figure environment shares the counter with lstlisting. However, you should ensure that lstlisting environments are floating too, otherwise the numbers could not agree and a figure could appear before a listing with a lower number.

\documentclass{article}
\usepackage{listings}

\makeatletter
\AtBeginDocument{%
  \let\c@figure\c@lstlisting
  \let\thefigure\thelstlisting
  \let\ftype@lstlisting\ftype@figure % give the floats the same precedence
}
\makeatother

\begin{document}
\begin{lstlisting}[caption=A listing,float]
a=1
\end{lstlisting}

\begin{lstlisting}[caption=Another,float]
b=2
\end{lstlisting}

\begin{figure}
F
\caption{A figure}
\end{figure}

\begin{lstlisting}[caption=Again,float]
c=3
\end{lstlisting}
\end{document}

Thanks to David Carlisle for noting the need for adjusting \ftype@lstlisting.

If you also want that table shares the counter, add similar instructions.

\documentclass{article}
\usepackage{listings}

\makeatletter
\AtBeginDocument{%
  \let\c@figure\c@lstlisting
  \let\thefigure\thelstlisting
  \let\c@table\c@lstlisting
  \let\thetable\thelstlisting
  \let\ftype@lstlisting\ftype@figure % give the floats the same precedence
  \let\ftype@table\ftype@figure % give the floats the same precedence
}
\makeatother

\begin{document}
\begin{lstlisting}[caption=A listing,float]
a=1
\end{lstlisting}

\begin{lstlisting}[caption=Another,float]
b=2
\end{lstlisting}

\begin{figure}
F
\caption{A figure}
\end{figure}

\begin{table}
G
\caption{A table}
\end{table}

\begin{lstlisting}[caption=Again,float]
c=3
\end{lstlisting}
\end{document}