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diff --git a/Master/texmf-doc/doc/english/FAQ-en/html/FAQ-tabcellalign.html b/Master/texmf-doc/doc/english/FAQ-en/html/FAQ-tabcellalign.html new file mode 100644 index 00000000000..bf41eb54fe4 --- /dev/null +++ b/Master/texmf-doc/doc/english/FAQ-en/html/FAQ-tabcellalign.html @@ -0,0 +1,109 @@ +<head> +<title>UK TeX FAQ -- question label tabcellalign</title> +</head><body> +<h3>How to alter the alignment of tabular cells</h3> +<p>One often needs to alter the alignment of a tabular <code>p</code> ('paragraph') +cell, but problems at the end of a table row are common. With a +<code>p</code> cell that looks like: +<blockquote> +<pre> +... & \centering blah ... \\ +</pre> +</blockquote> +one is liable to encounter errors that complain about a "misplaced +<code>\</code><code>noalign</code>" or "<a href="FAQ-altabcr.html">extra alignment tab</a>", or the like. +The problem is that the command <code>\\</code> means different things in +different circumstances: the <code>tabular</code> environment +switches the meaning to a value for use in the table, and +<code>\</code><code>centering</code>, <code>\</code><code>raggedright</code> and <code>\</code><code>raggedleft</code> all change the +meaning to something incompatible. Note that the problem only +arises in the last cell of a row: since each cell is set into a box, +its settings are lost at the <code>&</code> (or <code>\\</code>) that +terminates it. +<p>The simple (old) solution is to preserve the meaning of <code>\\</code>: +<blockquote> +<pre> +\newcommand\PBS[1]{\let\temp=\\% + #1% + \let\\=\temp +} +</pre> +</blockquote> +which one uses as: +<blockquote> +<pre> +... & \PBS\centering blah ... \\ +</pre> +</blockquote> +(for example). +<p>The technique using <code>\</code><code>PBS</code> was developed in the days of LaTeX 2.09 +because the actual value of <code>\\</code> that the <code>tabular</code> +environment uses was only available as an internal command. Nowadays, +the value is a public command, and you can in principle use it +explicitly: +<blockquote> +<pre> +... & \centering blah ... \tabularnewline +</pre> +</blockquote> +which may be incorporated into a simple macro as: +<blockquote> +<pre> +\newcommand{\RBS}{\let\\=\tabularnewline} +... +... & \centering\RBS blah ... \\ +</pre> +</blockquote> +and used as +<blockquote> +<pre> +... & \centering\RBS blah ... \\ +</pre> +</blockquote> +(note, you Preserve backslash with <code>\</code><code>PBS</code> <em>before</em> the command +that changes it, and Restore it with <code>\</code><code>RBS</code> <em>after</em> the +command; in fact, <code>\</code><code>RBS</code> is marginally preferable, but the old +trick lingers on). +<p>The <code>\</code><code>PBS</code> and <code>\</code><code>RBS</code> tricks also serve well in <i>array</i> +package "field format" preamble specifications: +<blockquote> + +<pre> +\begin{tabular}{... >{\centering\RBS}p{50mm}} +... +</pre> +</blockquote> +or +<blockquote> + +</blockquote> +<blockquote> +<pre> +\begin{tabular}{... >{\PBS\centering}p{50mm}} +... +</pre> +</blockquote> +In the <i>tabularx</i> and <i>tabulary</i> packages, there's a +command <code>\</code><code>arraybackslash</code> that has same effect as <code>\</code><code>RBS</code> (above); +so in those packages, one might say: +<blockquote> + +<pre> +\begin{tabular}{... >{\centering\arraybackslash}p{50mm}} +... +</pre> +</blockquote> +in place of the example above; in fact, the very latest (2003/12/01) +release of array.sty also provides a <code>\</code><code>tabularnewline</code> command, +that has the "basic tabular/array" meaning of '\\'. + +The command does rather lack brevity, but at least you don't have to +define it for yourself. +<dl> +<dt><tt><i>array.sty</i></tt><dd>Distributed as part of <a href="ftp://cam.ctan.org/tex-archive/macros/latex/required/tools.zip">macros/latex/required/tools</a> (<a href="ftp://cam.ctan.org/tex-archive/macros/latex/required/tools.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/macros/latex/required/tools/">browse</a>) +<dt><tt><i>tabularx.sty</i></tt><dd>Distributed as part of <a href="ftp://cam.ctan.org/tex-archive/macros/latex/required/tools.zip">macros/latex/required/tools</a> (<a href="ftp://cam.ctan.org/tex-archive/macros/latex/required/tools.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/macros/latex/required/tools/">browse</a>) +<dt><tt><i>tabulary.sty</i></tt><dd>Distributed as part of <a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/carlisle.zip">macros/latex/contrib/carlisle</a> (<a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/carlisle.tar.gz">gzipped tar</a>, <a href="http://www.tex.ac.uk/tex-archive/macros/latex/contrib/carlisle/">browse</a>) +</dl> + +<p><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=tabcellalign">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=tabcellalign</a> +</body> |