# Horizontal line of custom length like an —

Is there a way to get a custom-length horizontal line that appears like a "longer em-dash", if you will?

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I removed the xetex tag because the question is not XeTeX-specific. – lockstep Dec 20 '11 at 19:08

I defined a \threeemdash macro for use in bibliographies. A more general \xdash version accepts the dash length as optional argument.

\documentclass{article}

\newcommand*{\threeemdash}{\rule[0.5ex]{3em}{0.55pt}}

\newcommand*{\xdash}[1][3em]{\rule[0.5ex]{#1}{0.55pt}}

\begin{document}

Some text: \threeemdash

Some text: \xdash

Some text: \xdash[6em]

\end{document}


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If you're specifically interested in duplicating the en-dash look (which differs from a typical horizontal \rule), you could use leaders.

\documentclass{article}
\newcommand{\varendash}[1][5pt]{%
}
\begin{document}
Some text: -- \par
Some text: \varendash \par \medskip

Some text: --- \par
Some text: \varendash[10pt] \par \medskip

Some text: {---}{---}{---}{---}{---} \par
Some text: \varendash[50pt]
\end{document}


The above MWE provides \varendash[<len>] which typesets an en-dash -- within the space <len> (default is 5pt). Since the standard en-dash (--) has width 5pt, and em-dash (---) has width 10pt, using multiples of 5pt works best.

You could also define \varemdash in a similar context:

\newcommand{\varemdash}[1][10pt]{%

For more on leaders, see Want to fill line with repeating string. For have a line filled to the end of the text block (like \hrulefill), consider using the xhfill package.
@lockstep: Yes, there is a tiny gap in the PDF view, but this does not show up in print (just checked). Alternatively, using \leaders\hbox{--\kern-0.01pt}\hfill\kern0pt would remove the visual gap, but leave up to (probably) 4.99pt gap shorter than the specified length <len>, depending on the leader length. Do you know the actual thickness of an en-dash (or em-dash) in order to match that of the text character(s)? – Werner Dec 20 '11 at 20:09
No, I don't. The 0.55pt I used in my answer are more suited for Palatino (with thicker dashes) than for Computer Modern, though. – lockstep Dec 20 '11 at 20:29