How to add rule under content

Question

I would add a rule under CONTENTS like this:

How can I do? I have to use some particular package?

Answer 1

The following code may suit your needs:

\documentclass{article}
\usepackage{tocloft}
\renewcommand\contentsname{Contents}
\renewcommand\cfttoctitlefont{\Large\bfseries}
\renewcommand\cftaftertoctitle{\medskip\hrule\medskip}
\begin{document}
\tableofcontents
\section{Test}
\end{document}