Dollar signs in an edef yield tex capacity exceeded

Question

I want my two dollars:

\documentclass{minimal}
\begin{document}
\edef\twodollars{\$2}
\end{document}

However, all I get is:

! TeX capacity exceeded, sorry [input stack size=5000].
\font@name ->
             \OT1/cmr/m/n/10 
l.3 \edef\twodollars{\$
                       2}

Is it possible to use \edef with a value that includes a dollar sign?

@Werner: in the application the "2" is a macro \twoOrThree, and I want to use the value \twoOrThree has at the time of \twodollars definition, rather than the value at a later expansion of \twodollars. — Jack Schmidt, Nov 30 '11 at 5:10
Also, the dollar sign just has to look like a dollar sign when \twodollars is expanded in plain horizontal mode text. I didn't see a "\textdollarsign" like for underscore. — Jack Schmidt, Nov 30 '11 at 5:11

Werner · Accepted Answer · 2011-11-30 06:34:09Z

7

Use

\documentclass{minimal}
\begin{document}
\edef\twodollars{\string$2} \twodollars
\end{document}

\string changes the category code for $ to 12 (other).

answered Nov 30 '11 at 5:17

Werner

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Works like a charm, even in the convoluted mess of my real application. Thanks! – Jack Schmidt Nov 30 '11 at 5:19
@JackSchmidt: If you need this more often, consider defining a macro for the dollar. For example, the newverbs package allows for \Verbdef\dollar|$|, which also works for other special characters including %, where \string does not work. – Martin Scharrer♦ Dec 1 '11 at 8:59

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egreg · Accepted Answer · 2011-11-30 07:35:36Z

6

The correct way is to say

\makeatletter
\protected@edef\twodollars{\$2}
\makeatother

as \$ is defined via \DeclareRobustCommand. An alternative is to say

\usepackage{etoolbox}
\robustify\$
\edef\twodollars{\$2}

answered Nov 30 '11 at 7:35

egreg

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2 Answers 2