Re-using tikzmark names?

Question

It seems that tikzmark names can't be re-used. In the code below, I try to draw a box outline in the first lstlisting section, and a filled box in the second lstlisting section. In each lstlisting, I place two tikzmarks named "a" and "b". Unfortunately, the result is that the second lstlisting gets both the outline box and the filled box, but the first lstlisting gets neither.

If I rename the tikzmarks in one of the sections (say, "a1" and "b1") things work as expected. Is there a way to "forget" tikzmarks? I'm writing a document that will have a lot of code snippets, and it will be really tedious to keep track of unique tikzmarks for each of them.

Here's the sample code:

\documentclass{article}

\usepackage{listings}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,calc,shapes,positioning,tikzmark}

\begin{document}
\thispagestyle{empty}

\section{Box}
\begin{lstlisting}[escapechar=!,basicstyle=\ttfamily]
#include <stdio.h>
#include <math.h>

int main () {
  double c=-1;
  double z=0;
  int i;

  printf (``For c = %lf:\n'', c );
  for ( i=0; i<10; i++ ) {
    printf ( !\tikzmark{a}!``z %d = %lf\n''!\tikzmark{b}!, i, z );
    z = pow(z,2) + c;
  }
}
\end{lstlisting}

\begin{tikzpicture}[remember picture,overlay]
\draw[red,rounded corners]
  ([shift={(-3pt,2ex)}]pic cs:a) 
    rectangle 
  ([shift={(3pt,-0.65ex)}]pic cs:b);
\end{tikzpicture}


\section{Filled Box}
\begin{lstlisting}[escapechar=!,basicstyle=\ttfamily]
#include <stdio.h>
#include <math.h>

int main () {
  double c=-1;
  double z=0;
  int i;

  printf (``For c = %lf:\n'', c );
  for ( i=0; i<10; i++ ) {
    printf ( !\tikzmark{a}!"z %d = %lf\n"!\tikzmark{b}!, i, z );
    z = pow(z,2) + c;
  }
}
\end{lstlisting}

\begin{tikzpicture}[remember picture,overlay]
\draw[fill=gray,opacity=0.1]
  ([shift={(-3pt,2ex)}]pic cs:a) 
    rectangle 
  ([shift={(3pt,-0.65ex)}]pic cs:b);
\end{tikzpicture}


\end{document}

Answer 1

Here's a solution that uses the fact that tikzmarks can have prefixes and suffices. We create a new counter which we use as the automatically appended suffix. Then each time we use the tikzmarks that we've stored, we increment the counter. By wrapping it all in a few styles, the machinery is quite hidden.

For this to work in its current guise, you have to use the tikzmarks after they've been defined, but the key is when the counter is stepped so it could easily be adapted to a more general case.

\documentclass{article}
%\url{http://tex.stackexchange.com/q/284311/86}

\usepackage{listings}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,calc,shapes,positioning,tikzmark}

\newcounter{tmkcount}

\tikzset{
  use tikzmark/.style={
    remember picture,
    overlay,
    execute at end picture={
      \stepcounter{tmkcount}
    },
  },
  tikzmark suffix={-\thetmkcount}
}

\begin{document}
\thispagestyle{empty}

\section{Box}
\begin{lstlisting}[escapechar=!,basicstyle=\ttfamily]
#include <stdio.h>
#include <math.h>

int main () {
  double c=-1;
  double z=0;
  int i;

  printf (``For c = %lf:\n'', c );
  for ( i=0; i<10; i++ ) {
    printf ( !\tikzmark{a}!``z %d = %lf\n''!\tikzmark{b}!, i, z );
    z = pow(z,2) + c;
  }
}
\end{lstlisting}

\begin{tikzpicture}[use tikzmark]
\draw[red,rounded corners]
  ([shift={(-3pt,2ex)}]pic cs:a) 
    rectangle 
  ([shift={(3pt,-0.65ex)}]pic cs:b);
\end{tikzpicture}

\section{Filled Box}
\begin{lstlisting}[escapechar=!,basicstyle=\ttfamily]
#include <stdio.h>
#include <math.h>

int main () {
  double c=-1;
  double z=0;
  int i;

  printf (``For c = %lf:\n'', c );
  for ( i=0; i<10; i++ ) {
    printf ( !\tikzmark{a}!"z %d = %lf\n"!\tikzmark{b}!, i, z );
    z = pow(z,2) + c;
  }
}
\end{lstlisting}

\begin{tikzpicture}[use tikzmark]
\draw[fill=gray,opacity=0.1]
  ([shift={(-3pt,2ex)}]pic cs:a) 
    rectangle 
  ([shift={(3pt,-0.65ex)}]pic cs:b);
\end{tikzpicture}


\end{document}