# How to prevent arydshln from screwing up formatting inside table

Consider the following minimal working example:

\documentclass[a4paper,10pt]{scrbook}
\usepackage{longtable}
\usepackage{arydshln}

\begin{document}
\begin{longtable}[mc]{|c|c|cc|}
\hline
x &y &z &w\\
\cdashline{2-4}[2pt/5pt]
x2 &Y &z2 &w2\\
\hdashline[2pt/5pt]
x3 &Y &z3 &w3\\
\end{longtable}

\begin{table}[!ht]
\begin{longtable}[mc]{|c|c|cc|}
\hline
x &y &z &w\\
\cdashline{2-4}[2pt/5pt]
x2 &Y &z2 &w2\\
\hdashline[2pt/5pt]
x3 &Y &z3 &w3\\
\end{longtable}
\caption{Same Longtable, but encased inside a Table.}
\end{table}

Why do the vertical lines suddenly not work?
\end{document}


The undesidered behaviour is the mysterious disappearance of vertical lines, when longtables are places inside tables. Why is this happening and how do I stop this?

Note that the vertical lines reappear, when arydshln is removed, i. e. this package is responsible for the undesirable behaviour. On the other hand, I need the arydshln package, as it is really good at dashed lines (the only other alternative I could find is tabu, but that package will require massive changes to the huge number of longtables (to longtabu) in my document. So ideally I want to keep this package and prevent this behaviour. So what do I need to do?

UPDATE: The solution, as pointed out by @David Carlisle in the comments below, is to use tabular instead of longtable.

• why have you got a longtable inside a table? It can not possibly do anything useful there, just use a normal tabular. also what is the [mc] option to longtable? – David Carlisle Jul 13 at 20:16
• the same problem persists with \begin{tabular}. The [mc] option is just for vertical / horizontal alignment. It does not affect anything if you change this. – Thomas Jul 13 at 22:11
• My mistake, you're right in general of course, and using tabular worked. – Thomas Jul 13 at 23:00