Width of nested tabularx environments

Question

I am trying to create a RPG "character sheet" using LaTeX. For those unfamiliar with the madness of nested boxes, underlined whitespace etc. involved, this here gives a good impression (except that I want mine to look better, of course. ;-) )

I started with a \begin{tabularx{\textwidth}}{|X|X|X|}, and tried to nest tabular and tabularx ennvironments in that, intending to use \hrulefill to get the underlines.

The problem is, I'd like to make the nested tables as wide as the enclosing table cell allows, but don't know how to get to that value. 0.33\textwidth is only a rough guesstimate, and does not take into account cell padding and the like.

After looking at the tabularx documentation, I tried \TX@cell@width, but that gave me an error ("undefined control sequence").

Is there a way to get a value like \cellwidth or something, for the width definition of a nested tabularx? Or a package specialized for this kind of work? (I tried the MiKTeX package manager looking for something like it, but came up empty.)

Edit: Ups... forgot the MWE...

\documentclass{scrbook}

\usepackage{tabularx}

\begin{document}

\begin{tabularx}{\textwidth}{|X|X|X|}
\hline
{ \begin{tabularx}{\TX@col@width}{lX}  %% <-- this does *not* work...
Name: & \hrulefill\\
Race: & \hrulefill\\
Profession: & \hrulefill\\
\end{tabularx} } &
\Large\textbf{Character Sheet} &
Empty so far\\
\hline
\end{tabularx}
\end{document}

Answer 1

\documentclass{scrbook}

\usepackage{tabularx}
\makeatletter
\newcommand\cellwidth{\TX@col@width}
\makeatother

\begin{document}

\begin{tabularx}{\textwidth}{|X|X|X|}
\hline
{\begin{tabularx}{\cellwidth}{lX}  %% <-- this does *not* work...
Name: & \hrulefill\\
Race: & \hrulefill\\
Profession: & \hrulefill\\
\end{tabularx}}&
\Large\textbf{Character Sheet} &
Empty so far\\
\hline
\end{tabularx}
\end{document}

You can't use @-commands without protecting them between \makeatletter and \makeatother; it's best to do it beforehand. Note that the command is \TX@col@width.

Answer 2

why do you need the cell width? \hrulefill already works:

\begin{tabularx}{\textwidth}{|X|X|X|}
foo \rule{1cm}{0.4pt} \hrulefill &foo \hrulefill &foo \hrulefill
\end{tabularx}

However, in this case the columnwidth is \dimexpr \textwidth/3-6\tabcolsep