How to customize the figure numbering with a letter or special symbol?

Question

I want to distinguish the figure number by adding a letter, say "a", or a special symbol, such as \star, between the word "Figure" and number.

In other word, what I'd like to have is something like this

Figure a 1 or

Figure *1

Thank you.

Answer 1

Here are two versions: One with \DeclareCaptionLabelFormat and the other one by redefining the figure counter, but this will also change the appearance of figure in List of Figures, as such I don't recommend this.

\documentclass{article}




\usepackage{caption}

\newcommand{\specialformattingstuff}{*} % or use \textasteriskcentered


\let\origthefigure\thefigure

\DeclareCaptionFormat{cancaption}{#1#2#3\par} % Normal format actually
\DeclareCaptionLabelFormat{cancaptionlabel}{#1 \specialformattingstuff#2}

\begin{document}
\listoffigures
\captionsetup[figure]{format=cancaption,labelformat=cancaptionlabel}
\begin{figure}
  \caption{Foo figure}
\end{figure}

% Redefinition of counter output -- I don't recommend this
\renewcommand{\thefigure}{a \origthefigure}
% Restore to the default format 
\captionsetup[figure]{format=plain,labelformat=default}
\begin{figure}
  \caption{Foo figure}
\end{figure}


\end{document}

Answer 2

\setcounter{figure}{0}

\renewcommand{\thefigure}{A\arabic{figure}}