Making subsections be numbered with A,B,C,

Question

I'm using the book class. My chapters are numbered with 1,2,3,... I have already managed to have my sections be numbered with only 1,2,3,... (they reset upon a new chapter).

How can I number my subsections with A,B,C,... such that they reset to A upon new sections/chapters?

Answer 1

Since by default the counter for subsections will reset every new section, all you have to do is to redefine the \thesubsection command controlling the representation of the subsection counter:

\renewcommand\thesubsection{\Alph{subsection}}

A little example:

\documentclass{book}

\renewcommand\thesubsection{\Alph{subsection}}

\begin{document}

\chapter{test}
\section{test}
\subsection{test}
\subsection{test}
\section{test}
\subsection{test}
\subsection{test}

\end{document}

The above solution won't work as expected if you use a \subsection immediately after a \chapter command (without issuing a \section in between); to cope for this situation, you can use the chngcntr package to make the subsection counter reset also when the chapter counter is incremented:

\documentclass{book}
\usepackage{chngcntr}

\counterwithin{subsection}{chapter}
\renewcommand\thesection{\arabic{section}}
\renewcommand\thesubsection{\Alph{subsection}}

\begin{document}

\chapter{test}
\section{test}
\subsection{test}
\subsection{test}
\section{test}
\subsection{test}
\subsection{test}

\chapter{test}
\subsection{test}
\subsection{test}

\end{document}