How do I get the \cancel (strikeout) in Plain TeX?

Question

I've searched both online and in the TexBook, but can not find a command or package.

Note, I am pretty new to TeX / LaTeX, but am currently trying to figure out how to do things in Plain TeX.

Edit: Thanks for all the answers, but I realized that my question was ambiguous because I used the word "strikeout" which is commonly associated with the horizontal line. I am actually looking for the diagonal strikeout, like the one here, except for Plain TeX. How to strike through obliquely, e.g. to indicate cancellation?

Also, I am looking for a solution that works in Math mode.

Answer 1

Package ulem

Timebandit had written a solution with package ulem. The example was given as LaTeX, but the package also works with plain TeX:

\input ulem.sty

\sout{Hello World}

\bye

Package soul

Another LaTeX package soul can be used with plain TeX:

\input soul.sty

\st{Hello World}

\bye

Answer 2

this technique has been used for years for maintenance of the tug bylaws. it's really only good for short phrases, and won't break at the end of a line; also, the spaces between words are "frozen". but if those restrictions fit your application, then it works reliably.

\newbox\TestBox
\def\Remove #1 {\setbox\TestBox=\hbox{#1}%
        \leavevmode\rlap{\vrule height 2.5pt depth-1.75pt width\wd\TestBox}%
        \box\TestBox\ }
\def\0{\Remove}
\def\Replaceby #1{{\bf #1}}
\def\1{\Replaceby}

\0{Remove this text.}

\1{Replace it by this text}.

\bye

Answer 3

If you are using one of the newer Unicode based TeX engines (xetex or luatex) an alternative method would be to use Unicode combining characters to get the strike. The effect then depends on the font you used, I have to say I was a bit disappointed with the result with Arial, but here it is:

\font \tenrm="[Arial]"
\tenrm


O̶h̶ ̶n̶o̶ ̶I̶ ̶d̶i̶d̶ ̶i̶t̶ ̶w̶r̶o̶n̶g̶!̶


\bye