How to reset section counter

This is the barebones of my document:

\documentclass[12pt]{article}

\begin{document}

\begin{center}
\textbf{\LARGE{Topic I}}
\end{center}

\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\begin{center}
\textbf{\LARGE{Topic II}}
\end{center}

\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\end{document}


which displays like

.

I want the section numbering to restart at Topic II.

Instead of providing headings manually (which can be prone-error and implies a lot of manual intervention), you can redefine the \part command to give the desired layout; then you can make the section counter reset every time part is incremented:

\documentclass[12pt]{article}

\makeatletter
\def\@part[#1]#2{%
\ifnum \c@secnumdepth >\m@ne
\refstepcounter{part}%
\else
\fi
{\parindent \z@ \raggedright
\interlinepenalty \@M
\normalfont\centering
\ifnum \c@secnumdepth >\m@ne
\LARGE\bfseries \partname\nobreakspace\thepart
\par\nobreak
\fi
\huge \bfseries #2%
\markboth{}{}\par}%
\nobreak
\vskip 3ex
\renewcommand\partname{Topic}
\makeatother

\begin{document}

\part{}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\part{}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\end{document}


Using the xpatch package you can simplify the code:

\documentclass[12pt]{article}
\usepackage{xpatch}

\makeatletter
\xpatchcmd{\@part}{\normalfont}{\normalfont\centering}{}{}
\xpatchcmd{\@part}{\Large}{\LARGE}{}{}
\renewcommand\partname{Topic}
\makeatother

\begin{document}

\part{}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\part{}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\end{document}


Another variant, using this time the titlesec package to easily customize the \part command, suppressing the "Part #" label and centering the title:

\documentclass[12pt]{article}
\usepackage{titlesec}

\makeatletter
\makeatother
\titleformat{\part}[display]
{\normalfont\LARGE\bfseries\centering}{}{0pt}{}

\begin{document}

\part{Polynomials}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\part{Functions}
\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\end{document}


• Ok I like the solution suggested in your addendum. But... one more favor to ask.... I don't want "Topic I", "Topic II", etc; those were just placeholders for actual topic names that I will add in (for example, "Polynomials", "Functions") – Frank Epps Jul 20 '13 at 0:14
• @FrankEpps OK. Give me some minutes more. – Gonzalo Medina Jul 20 '13 at 0:18
• +1, I'm never going to catch up with @egreg at this rate:-) – David Carlisle Jul 20 '13 at 0:20
• @FrankEpps please see my updated answer. – Gonzalo Medina Jul 20 '13 at 0:21
• THANK YOU SO MUCH!!!! And David, don't feel bad, you're a great guy!! – Frank Epps Jul 20 '13 at 0:22
\documentclass[12pt]{article}

\makeatletter
\makeatother

\begin{document}

\part{Topic I}

\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\part{Topic II}

\section{Section I}
content

\section{Section II}
content

\subsection{Subsection I}
content

\subsection{Subsection II}
content

\section{Section III}
content

\end{document}


Note \LARGE does not take an argument and should always include the following end of paragraph so the syntax would be \begin{center}\bfseries\LARGE Topic I\end{center} but using explicit font changes rather than a section head is just not the LaTeX way:-) The formatting for a \part head can be separately customised to use a centred heading if that is desired.

• I'm a LaTeX noob and I can never seem to get things right using the built-in functionality of LaTeX so I just make my own headings lol. – Frank Epps Jul 20 '13 at 0:02
• can you make it look exactly like what I had? (center "Topic I" and delete the "Part I" headers) – Frank Epps Jul 20 '13 at 0:04
• @FrankEpps Did you see my answer? ;-) – Gonzalo Medina Jul 20 '13 at 0:05
• yes I did, I see that it works and it's exactly what I wanted :) but the large mass of code is putting me off... – Frank Epps Jul 20 '13 at 0:06
• @FrankEpps please see my updated answer. – Gonzalo Medina Jul 20 '13 at 0:11