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<head>
<title>UK TeX FAQ -- question label verbwithin</title>
</head><body>
<h3>Why doesn't <code>\</code><code>verb</code> work within ...?</h3>
<p>The LaTeX verbatim commands work by changing category codes.  Knuth
says of this sort of thing "Some care is needed to get the timing
right...", since once the category code has been assigned to a
character, it doesn't change.  So <code>\</code><code>verb</code> has to assume that it is
getting the first look at its parameter text; if it isn't, TeX has
already assigned category codes so that <code>\</code><code>verb</code> doesn't have a
chance.  For example:
<blockquote>
<pre>
\verb+\error+
</pre>
</blockquote>
will work (typesetting '<code>\</code><code>error</code>'), but
<blockquote>
<pre>
\newcommand{\unbrace}[1]{#1}
\unbrace{\verb+\error+}
</pre>
</blockquote>
will not (it will attempt to execute <code>\</code><code>error</code>).  Other errors one
may encounter are '<code>\</code><code>verb</code> ended by end of line', or even '<code>\</code><code>verb</code>
illegal in command argument'.
<p>This is why the LaTeX book insists that verbatim
commands must not appear in the argument of any other command; they
aren't just fragile, they're quite unusable in any command parameter,
regardless of <a href="FAQ-protect.html"><code>\</code><code>protect</code>ion</a>.  (The <code>\</code><code>verb</code>
command tries hard to detect if you're misusing it; unfortunately, it
can't always do so, and the error message is therefore not a reliable
indication of problems.)
<p>The first question to ask yourself is: "is <code>\</code><code>verb</code> actually
necessary?".
<ul>
<li> If <code>\</code><code>texttt{<em>your text</em>}</code> produces the same result
  as <code>\</code><code>verb</code><code>+<em>your text</em>+</code>, then there's no need of
  <code>\</code><code>verb</code> in the first place.
<li> If you're using <code>\</code><code>verb</code> to typeset a URL or email
  address or the like, then the <code>\</code><code>url</code> command from the
  <i>url</i> package will help: it doesn't suffer from the problems
  of <code>\</code><code>verb</code>.
<li> If you're putting <code>\</code><code>verb</code> into the argument of a boxing
  command (such as <code>\</code><code>fbox</code>), consider using the <code>lrbox</code>
  environment:
<blockquote>
<pre>
\newsavebox{\mybox}
...
\begin{lrbox}{\mybox}
  \verb!VerbatimStuff!
\end{lrbox}
\fbox{\usebox{\mybox}}
</pre>
</blockquote>
</ul>
<p>Otherwise, there are three partial solutions to the problem.
<ul>
<li> Some packages have macros which are designed to be responsive
  to verbatim text in their arguments.  For example,
  the <i>fancyvrb</i> package defines a command
  <code>\</code><code>VerbatimFootnotes</code>, which redefines the <code>\</code><code>footnotetext</code> (and
  hence the <code>\</code><code>footnote</code>) commands in such a way that you can include
  <code>\</code><code>verb</code> commands in its argument.  This approach could in
  principle be extended to the arguments of other commands, but it can
  clash with other packages: for example, <code>\</code><code>VerbatimFootnotes</code>
  interacts poorly with the <code>para</code> option to the <i>footmisc</i>
  package.
<p>  The <i>memoir</i> class defines its <code>\</code><code>footnote</code> command so that
  it will accept verbatim in its arguments, without any supporting package.
<li> The <i>fancyvrb</i> package defines a command <code>\</code><code>SaveVerb</code>,
  with a corresponding <code>\</code><code>UseVerb</code> command, that allow you to save
  and then to reuse the content of its argument; for details of this
  extremely powerful facility, see the package documentation.
<p>  Rather simpler is the <i>verbdef</i> package, which defines a
  (robust) command which expands to the verbatim argument given.
<li> If you have a single character that is giving trouble (in
  its absence you could simply use <code>\</code><code>texttt</code>), consider using
  <code>\</code><code>string</code>.  <code>\</code><code>texttt{my<code>\</code><code>string</code>_</code>name}
  typesets the same as 
  <code>\verb+my_name+</code>, and will work in the argument of a command.  It
  won't, however, work in a moving argument, and no amount of
  <a href="FAQ-protect.html"><code>\</code><code>protect</code>ion</a> will make it work in
  such a case.
<p>  A robust alternative is:
  <blockquote>
<pre>
\chardef\bs=`\_
...
\section{... \texttt{my\bs name}}
</pre>
  </blockquote>
  Such a definition is 'naturally' robust; the construction
  "&lt;<i>back-tick</i>&gt;<code>\</code><code>&lt;<i>char</i>&gt;</code>" may be used for any
  troublesome character (though it's plainly not necessary for things
  like percent signs for which (La)TeX already provides
  robust macros).
</ul>
Documentation of both <i>url</i> and <i>verbdef</i> is in the
package files.
<dl>
<dt><tt><i>fancyvrb.sty</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/fancyvrb.zip">macros/latex/contrib/fancyvrb</a> (<a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/fancyvrb.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/macros/latex/contrib/fancyvrb/">browse</a>)
<dt><tt><i>memoir.cls</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/memoir.zip">macros/latex/contrib/memoir</a> (<a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/memoir.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/macros/latex/contrib/memoir/">browse</a>)
<dt><tt><i>url.sty</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/misc/url.sty">macros/latex/contrib/misc/url.sty</a>
<dt><tt><i>verbdef.sty</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/misc/verbdef.sty">macros/latex/contrib/misc/verbdef.sty</a>
</dl>
<p><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=verbwithin">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=verbwithin</a>
</body>