[texhax] Any crazy math formulas for testing a TeX language interpreter

[David Carlisle]

On 13 January 2016 at 19:04, Douglas McKenna <doug at mathemaesthetics.com>
wrote:

> Joseph Wright wrote -
>
> > In any case, some form of expandable comparison that ignores catcodes is
> > very useful, and it's essential to use expl3 (we found some years ago
> > that this was the one post-e-TeX primitive that was vital in all cases,
> > though as David notes once you get to dealing with Unicode then some
> > ability to generate tokens across the full range is also needed).
>
>
> So … something like a three-way switch, e.g.,
>
> \ifstrcmp <char token list> <char token list>
>      <case 0 for less than> \or
>      <case 1 for equal> \or
>      <case 2 for greater than>
>      \fi
>
> ?
>
> Or a two-way explicit comparison of some kind, e.g.,
>
> \ifstrcmp { <char token list> } < = > { <char token list> }
>                 TRUE
>         \else
>                 FALSE
>         \fi
>
> ?
>


see
 pdftex manual (page 37) which says:

 \pdfstrcmp {general text} { general text }(expandable)

 This command compares two strings and expands to 0 if the strings are
equal, to -1 if the first string
 ranks before the second, and to 1 otherwise. The primitive was introduced
in pdfTEX 1.30.0.

David
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