Roman numerals for sections and subsections

Question

I want to have my sections numbered using Roman numerals. However, I can only get the section number to be a Roman numeral, not the subsection. Here is some code:

\renewcommand{\thesection}{\Roman{section}} 
\renewcommand{\thesubsection}{\Roman{subsection}}

This will print, e.g. I. , whereas it should be I.I. Commenting out the second line gives the result I.1, which is not demanded.

Answer 1

You need to append the section number to the subsection number using:

\documentclass{article}
\renewcommand{\thesection}{\Roman{section}} 
\renewcommand{\thesubsection}{\thesection.\Roman{subsection}}
\begin{document}
\section{First section}
\subsection{First subsection}
\subsection{Second subsection}
\section{Second section}
\subsection{First subsection}
\subsection{Second subsection}
\end{document}

Answer 2

\renewcommand{\thesection}{\Roman{section}
\renewcommand{\thesubsection}{\thesection.\Roman{subsection}}