Article 11023 of comp.text.tex:
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From: nakasima@aoi.kuis.kyoto-u.ac.jp (Hiroshi Nakashima)
Subject: Dash line for LaTeX array/tabular
Message-ID: <NAKASIMA.93Apr1194305@aoi.kuis.kyoto-u.ac.jp>
Sender: news@kuis.kyoto-u.ac.jp
Nntp-Posting-Host: aoi.kuis.kyoto-u.ac.jp
Reply-To: nakasima@kuis.kyoto-u.ac.jp
Organization: Dept. of Info. Sci., Kyoto Univ., JAPAN
Distribution: comp
Date: Thu, 1 Apr 1993 10:43:04 GMT
Lines: 310

About three month ago, Weimin Zhang (weimin@panda.Levels.UniSA.Edu.Au)
kindly posted my style file hvdashln.sty, which draws horizontal/
vertical lines in LaTeX array/tabular environment, to this news group.
The style file, unfortunately, has a know problem that vertical lines
are broken when an array contains tall rows.

About one month ago, Monty Hayes (mhh3@gauss.eedsp.gatech.edu)
complained of this problem and I decided to make a new version,
arydshln.sty, to solve the problem.  The new style also has new
features, such as allowing `:' to specify vertical dash line in
preamble, and \cdashline being a counterpart of \cline.  However,
since the style is considerably heavy, I must recommend using the old
version unless the problem is serious.

Anyway, here is the new version.  Enjoy!
-----------------------------------------------------------------
Hiroshi Nakashima (nakasima@kuis.kyoto-u.ac.jp)
Dept. of Information Science, Faculty of Engineering, Kyoto Univ.
Yoshida Hon-Machi, Sakyo-Ku, Kyoto, 606-01 Japan.    +75-753-5383
-----------------------------------------------------------------
% arydshln.sty		v1.0 (April 1, 1993)
% 	by Hiroshi NAKASHIMA (nakasima@kuis.kyoto-u.ac.jp)
%
% Dahsed horizontal/vertical line for LaTeX array/tabular environment.
%
%	\hdashline		dashed \hline
%	\cdashline		dashed \cline
%	`:' in preamble		dashed `|'
%
%	\hdashlinewidth		length of dash segment (default = 4pt)
%	\hdashlinegap		gap between dash segments (default = 4pt)
%
% Ussage
%
%	\begin{array}{|l:c:r|}		% or \begin{tabular}/\begin{tabular*}
%	    A&B&C\\\hdashline		% draw dashed \hline
%	    AAA&BBB&CCC\\\cdashline{1-2}% draw dashed \cline
%	    \multicolumn{2}{|l:}{AB}&C\\
%	    	\\hdashline\hdashline	% draw dashed \hline\hline
%	\end{array}
%
%		|
%		V
%
%	| A   :  B  :   C |
%	+ - - + - - + - - +
%	| AAA : BBB : CCC |
%	+ - - + - - +     |
%	| AB        :   C |
%	+ - - + - - + - - +
%	+ - - + - - + - - +
%
% Bugs
%
% 1. Since this style file strongly depends on the coding for array/tabular
%    of LaTeX Version 2.09, it may be in compatible with higher versions.
%
% 2. Processing speed for array/tabular will become slower, even if dashed
%    lines are not included.
%
% 3. `:' in preamble should not be followed by `|' nor `@'.
%
% 4. Gap size varies depending on the dash line length.

% Modification of LaTeX's array/tabular

\def\endarray{\hdl@endarray \egroup\egroup \hdl@arrayrestore}
\def\endtabular{\hdl@endarray \egroup\egroup \hdl@arrayrestore $\egroup}
\expandafter\let\csname endtabular*\endcsname = \endtabular

\def\@array[#1]#2{\setbox\@arstrutbox=\hbox{\vrule 
		height\arraystretch \ht\strutbox
		depth\arraystretch \dp\strutbox
		width\z@}%
	\hdl@arrayinit
	\@mkpream{#2}\edef\@preamble{\halign \noexpand\@halignto
		\bgroup \tabskip\z@ \@arstrut \@preamble \tabskip\z@ \cr}%
	\let\@startpbox\@@startpbox \let\@endpbox\@@endpbox
	\hdl@preaminit
	\if #1t\vtop \else \if#1b\vbox \else \vcenter \fi\fi
	\bgroup \let\par\relax
	\let\@sharp##\let\protect\relax \lineskip\z@\baselineskip\z@\@preamble}

\def\@xarraycr{\@ifnextchar[{\@argarraycr}{\ifnum0=`{\fi}${}\hdl@cr}}
\def\@xtabularcr{\@ifnextchar[{\@argtabularcr}{\ifnum0=`{\fi}\hdl@cr}}
\def\@xargarraycr#1{\@tempdima #1\advance\@tempdima \dp \@arstrutbox 
	\vrule \@height\z@ \@depth\@tempdima \@width\z@
	\hdl@argcr\@tempdima}
\def\@yargarraycr#1{\hdl@argcr{-#1}\noalign{\vskip #1}}

\def\multicolumn#1#2#3{\multispan{#1}\begingroup
	\def\hdl@arraydashrule{\ifnum\@lastchclass=6\relax
			\@addtopreamble{\hdl@vdashrule{\hdl@currentcolumn}}%
		\else\@tempcnta#1\advance\@tempcnta\hdl@currentcolumn
			\@addtopreamble{\hdl@vdashrule{\the\@tempcnta}}\fi}%
	\@mkpream{#2}%
	\def\@sharp{#3}\let\protect\relax
	\let\@startpbox\@@startpbox\let\@endpbox\@@endpbox
	\hdl@preaminit
	\@arstrut \@preamble\endgroup
	\global\advance\hdl@currentcolumn#1\ignorespaces}

\def\@addamp{\if@firstamp\@firstampfalse \else
	\edef\@preamble{\@preamble \global\advance\hdl@currentcolumn\@ne &}%
	\advance\hdl@columns\@ne \fi}
\let\hdl@mkpream\@mkpream

\def\@mkpream{\hdl@columns\@ne \let\hdl@vdashrule\relax \let\hdl@colhtdp\relax
	\hdl@mkpream}

\def\@arrayclassz{\ifcase \@lastchclass \@acolampacol \or \@ampacol \or
		\or \or \@addamp \or
		\@acolampacol \or \@firstampfalse \@acol \fi
	\edef\@preamble{\@preamble
		\ifcase \@chnum 
		\hfil\hdl@putcolumn{$\relax\@sharp$}\hfil
		\or \hdl@putcolumn{$\relax\@sharp$}\hfil
		\or \hfil\hdl@putcolumn{$\relax\@sharp$}\fi}}
\def\@tabclassz{\ifcase \@lastchclass \@acolampacol \or \@ampacol \or
		\or \or \@addamp \or
		\@acolampacol \or \@firstampfalse \@acol \fi
	\edef\@preamble{\@preamble
	\ifcase \@chnum 
		\hfil\hdl@putcolumn{\@sharp\unskip}\hfil 
		\or \hdl@putcolumn{\@sharp\unskip}\hfil 
		\or \hfil\hskip\z@ \hdl@putcolumn{\@sharp\unskip}\fi}}

\def\@testpach#1{\@chclass \ifnum \@lastchclass=\tw@ 4 \else 
	\ifnum \@lastchclass=3 5 \else
		\z@ \if #1c\@chnum \z@ \else
			\if #1l\@chnum \@ne \else
			\if #1r\@chnum \tw@ \else
		\@chclass \if #1|\@ne \let\@arrayrule\hdl@arrayrule \else
			\if #1:\@ne \let\@arrayrule\hdl@arraydashrule \else
			\if #1@\tw@ \else
			\if #1p3 \else \z@ \@preamerr 0\fi
	\fi  \fi  \fi  \fi  \fi  \fi  \fi \fi}

\def\hline{\noalign{\ifnum0=`}\fi \hrule\@height\arrayrulewidth
	\hdl@hline\arrayrulewidth
	\let\@tempb\hline\futurelet\@tempa\hdl@xhline}

\def\@@startpbox#1{\setbox\hdl@box\vtop\bgroup\hsize#1\@arrayparboxrestore}
\def\@@endpbox{\par\vskip\dp\@arstrutbox\egroup\hdl@colhtdp\box\hdl@box\hfil}

% Register declaration

\newdimen\hdashlinewidth \hdashlinewidth4pt %
\newdimen\hdashlinegap \hdashlinegap4pt %
\newif\ifhdl@drawing
\newif\ifhdl@doublerule
\newcount\hdl@totalheight \newcount\hdl@totalheightsave
\newcount\hdl@columns
\newcount\hdl@currentcolumn \newcount\hdl@currentcolumnsave
\newbox\hdl@box
\newdimen\hdl@height \newdimen\hdl@heightsave
\newdimen\hdl@depth \newdimen\hdl@depthsave

\gdef\hdl@vdashcolumn{}
\gdef\hdl@vdashcols{}

% \hdashline and \cdashline

\def\hdashline{\multispan{\hdl@columns}\unskip\hdl@hcline
	\noalign{\ifnum0=`}\fi
	\let\@tempb\hdashline\futurelet\@tempa\hdl@xhline}

\def\hdl@xhline{\ifx\@tempa\hline \hdl@ixhline\fi
	\ifx\@tempa\hdashline \hdl@ixhline\fi
	\ifnum0=`{\fi}}
\def\hdl@ixhline{\vskip\doublerulesep\hdl@hline\doublerulesep}

\def\hdl@hline#1{\@tempcnta#1
	\global\advance\hdl@totalheight\@tempcnta
	\xdef\hdl@vdashcols{\hdl@vdashcols
		(-1,-1,/\the\@tempcnta);}}

\def\hdl@hcline{\vrule\@height\arrayrulewidth\@width\hdashlinewidth
	\hskip.5\hdashlinegap
	\xleaders\hbox{\hskip.5\hdashlinegap
		\vrule\@height\arrayrulewidth\@width\hdashlinewidth
		\hskip.5\hdashlinegap}\hfill
	\hskip.5\hdashlinegap
	\vrule\@height\arrayrulewidth\@width\hdashlinewidth\cr
	\noalign{\vskip-\arrayrulewidth}}

\def\cdashline#1{\hdl@cline[#1]}
\def\hdl@cline[#1-#2]{\noalign{\global\@cla#1\relax
		\global\advance\@cla\m@ne
		\ifnum\@cla>0\global\let\@gtempa\hdl@clinea\else
			\global\let\@gtempa\hdl@clineb\fi
		\global\@clb#2\relax
		\global\advance\@clb-\@cla}\@gtempa}

\def\hdl@clinea{\multispan\@cla&\multispan\@clb\unskip\hdl@hcline}
\def\hdl@clineb{\multispan\@clb\unskip\hdl@hcline}

% Initiation and preamble

\def\hdl@arrayinit{
	\hdl@totalheightsave\hdl@totalheight \global\hdl@totalheight\z@
	\hdl@currentcolumnsave\hdl@currentcolumn \global\hdl@currentcolumn\z@
	\hdl@heightsave\hdl@height \global\hdl@height\z@
	\hdl@depthsave\hdl@depth \global\hdl@depth\z@
	\edef\hdl@vdashcolumnsave{\hdl@vdashcolumn}\gdef\hdl@vdashcolumn{}%
	\edef\hdl@vdashcolssave{\hdl@vdashcols}\gdef\hdl@vdashcols{}}
\def\hdl@preaminit{\let\hdl@vdashrule\hdl@@vdashrule
	\let\hdl@colhtdp\hdl@@colhtdp}

\def\hdl@putcolumn#1{\setbox\hdl@box\hbox{#1}\hdl@colhtdp \box\hdl@box}
\def\hdl@@colhtdp{%
	\ifdim\hdl@height<\ht\hdl@box \global\hdl@height\ht\hdl@box \fi
	\ifdim\hdl@depth<\dp\hdl@box \global\hdl@depth\dp\hdl@box\fi}

\let\hdl@arrayrule\@arrayrule
\def\hdl@arraydashrule{\ifnum\@lastchclass=6\relax
		\@addtopreamble{\hdl@vdashrule{0}}%
	\else \@addtopreamble{\hdl@vdashrule{\the\hdl@columns}}\fi}

\def\hdl@@vdashrule#1{\xdef\hdl@vdashcolumn{\hdl@vdashcolumn#1,}}

% End of row

\def\hdl@cr{\cr\noalign{\hdl@@cr\z@}}
\def\hdl@argcr#1{\cr\noalign{\hdl@@cr{#1}}}
\def\hdl@@cr#1{
	\ifdim\hdl@height<\ht\@arstrutbox \hdl@height\ht\@arstrutbox\fi
	\ifdim\hdl@depth<\dp\@arstrutbox \hdl@depth\dp\@arstrutbox\fi
	\@tempcnta\hdl@height \advance\@tempcnta\hdl@depth
	\@tempdima#1\advance\@tempcnta\@tempdima
	\global\advance\hdl@totalheight\@tempcnta
	\xdef\hdl@vdashcols{\hdl@vdashcols
		(\hdl@vdashcolumn-1,-1,/\the\@tempcnta);}%
	\gdef\hdl@vdashcolumn{}\global\hdl@currentcolumn\z@
	\global\hdl@height\z@ \global\hdl@depth\z@}

% End of array/tabular

\def\hdl@endarray{\crcr \noalign{
	\ifdim\hdl@height=\z@
		\ifdim\hdl@depth=\z@ \else \hdl@@cr\z@ \fi
	\else \hdl@@cr\z@ \fi}\omit
	\def\hdl@vdrow{}\global\let\hdl@vd\relax
	\global\let\hdl@amp\relax \global\let\hdl@omit\relax
	\hdl@makevd
	\global\let\hdl@vd\hdl@@vd
	\global\let\hdl@amp\hdl@@amp \global\let\hdl@omit\hdl@@omit
	\hdl@vdrow\cr}
\def\hdl@arrayrestore{\global\hdl@totalheight\hdl@totalheightsave
	\global\hdl@currentcolumn\hdl@currentcolumnsave
	\global\hdl@height\hdl@heightsave
	\global\hdl@depth\hdl@depthsave
	\xdef\hdl@vdashcolumn{\hdl@vdashcolumnsave}%
	\xdef\hdl@vdashcols{\hdl@vdashcolssave}}
\def\hdl@@amp{&}
\def\hdl@@omit{\omit}

\def\hdl@makevd{\@tempcnta\hdl@totalheight \@tempcntb\hdl@totalheight
	\hdl@drawingfalse \def\@tempb{}%
	\hdl@doublerulefalse
	\expandafter\hdl@imakevd\hdl@vdashcols\@nil;%
	\ifhdl@drawing \hdl@drawvd \fi
	\edef\hdl@vdashcols{\@tempb}%
	\ifhdl@doublerule
		\edef\hdl@vdrow{\hdl@vdrow\hskip\doublerulesep}%
		\let\next\hdl@makevd
	\else
		\advance\hdl@currentcolumn\@ne
		\ifnum\hdl@currentcolumn>\hdl@columns \let\next\relax
		\else
			\ifnum\hdl@currentcolumn=\@ne
				\edef\hdl@vdrow{\hdl@vdrow\hfil}%
			\else
				\edef\hdl@vdrow{\hdl@vdrow
					\hdl@amp \hdl@omit \hfil}%
			\fi
			\let\next\hdl@makevd
	\fi\fi\next}
\def\hdl@imakevd#1;{\def\@tempa{#1}\ifx\@tempa\@nnil \let\next\relax
	\else \hdl@iimakevd#1\let\next\hdl@imakevd \fi \next}
\def\hdl@iimakevd(#1/#2){\hdl@iiimakevd#1\@nil
	\edef\@tempb{\@tempb(\@tempc/#2);}\advance\@tempcntb-#2}
\def\hdl@iiimakevd#1,#2,#3\@nil{%
	\ifnum#1<\z@\def\@tempc{-1,-1,}%
		\ifhdl@drawing \hdl@drawvd \hdl@drawingfalse \fi
	\else
		\ifnum#1=\hdl@currentcolumn \relax
			\ifhdl@drawing \else
				\@tempcnta\@tempcntb \hdl@drawingtrue
			\fi
			\def\@tempc{#2,#3}%
			\ifnum#1=#2\relax \hdl@doubleruletrue \fi
		\else
			\ifhdl@drawing \hdl@drawvd \hdl@drawingfalse \fi
			\def\@tempc{#1,#2,#3}%
	\fi\fi}
\def\hdl@drawvd{\advance\@tempcnta-\@tempcntb
	\edef\hdl@vdrow{\hdl@vdrow \hdl@vd{\the\@tempcntb}{\the\@tempcnta}}}

\def\hdl@@vd#1#2{\vbox to\z@{\vss\hbox{\hskip-.5\arrayrulewidth
	\raise#1sp\vbox to#2sp{
		\hrule\@height.5\hdashlinewidth\@width\arrayrulewidth
		\vskip.5\hdashlinegap
		\xleaders\vbox{\vskip.5\hdashlinegap
			\hrule\@height\hdashlinewidth\@width\arrayrulewidth
			\vskip.5\hdashlinegap}\vfil
		\vskip.5\hdashlinegap
		\hrule\@height.5\hdashlinewidth\@width\arrayrulewidth}%
	\hskip-.5\arrayrulewidth}}}