How to underline section-headings in LaTeX?

Question

EDIT: As I see in the first answer, underline is the wrong word. I want a line under the section heading, separating the heading from the following text.

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Answer 1

Another way could be:

\begin{center}
\line(1,0){400}
\end{center}

Answer 2

Rewriting your command like this should do the trick:

\newcommand{\tmpsection}[1]{}
\let\tmpsection=\section
\renewcommand{\section}[1]{\tmpsection{\underline{#1}}}

This will evaluate to

\section { \underline {#1} }

which in turn produces underlined section headings :)

Answer 3

I've heard that the titlesec is more powerful than sectsty package, so I've just used it. You can put the horizontal line before the section header using:

\usepackage{titlesec}
\titleformat{\section}{\large\bfseries}{\thesection}{1em}{\hrule}

or you can put it after, with the help of newcommand. See section 4.4 of the titlesec manual.

Answer 4

You can do this with the \sectionrule command in the sectsty package.

Answer 5

You might take a look at the LaTeX \rule command:

\rule[raise-height]{width}{thickness}

However, that's an inline (horizontal) command, so you'll have to use some trickery to get it at the right position and size (\noindent and \textwidth should help a little).

Otherwise, you can use the following plain TeX

\smallskip
\hrule height 2pt
\smallskip

It doesn't really fit in the LaTeX syntax, but it works like a charm, and is guaranteed to span the entire text width.