[texhax] Finding ascii value of a parameter

[Ross Moore]

Hello Michael,

On Thu, 23 Oct 2003, Michael Barr wrote:

> The code
> \newcount \temp
> \temp`\a
        ^--------  this \ is redundant
> \showthe\temp
>
> will produce 97, the ascii code for a.  Is there any way to define a macro
> \ascii with the property that
> \ascii a
> \showthe\temp
> will produce the number 97 in the same way?

Yes, very easily.
You don't even need to use \newcount , which wastes a \count register;
 --- anyway, it's probably more convenient to have a text representation
of the character-code, accessible within a macro:

 \def\ascii#1{\bgroup
   \count0`#1\relax
   \xdef\asciicode{\the\count0}%
  \egroup}

\ascii a
\show\asciicode

\ascii &
\show\asciicode



However to get the \mathcode of mathematical symbols
is trickier; e.g.  \show\alpha
gives              \alpha=\mathchar"10B

To get that hex value "10B you'll need something like:


{\let\z\catcode \let\y\gdef \global\let\zz\count
 \z`m=12 \z`a=12 \z`t=12 \z`h=12 \z`c=12 \z`r=12
 \y\zzz#1mathchar#2@!@{\zz0=#2}%
}
\def\mathscii#1{{\expandafter\zzz\meaning#1@!@%
 \xdef\mathsciicode{\the\count0}}}

\mathscii\alpha
\show\mathsciicode

 should give you  276  as the \mathcode value.



Hope this helps,

	Ross Moore


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