[texhax] "Programming" in LaTeX

[Heiko Oberdiek]

Hello,

On 2018-02-22 15:48, Malte Thoma wrote:
> \documentclass{article}
> \usepackage{xstring,ifthen}
> \newcommand{\mytest}[1]{%

>     \newcommand{\s}{\StrChar{#1}{3}}

This stores the complete macro \StrChar with
parameters in macro \s. Because macro \StrChar
is not full expandable, \s does *not* expand to "c"
in the example.

Use the optional argument of \StrChar to store the
result in \s:

     \StrChar{#1}{3}[\s]%

>     \newcommand{\x}{c}
>     3rd charactor of input is: \s ~equal to \x \\
>     1st test: \IfStrEq{\x}{c}{true}{false} \\
>     2nd test: \IfStrEq{\s}{c}{true}{false}
> }
> \begin{document}
>     \mytest{abcd}
> \end{document}

Yours sincerely
   Heiko