[texhax] detect characters in strings
Uwe Lueck
uwe.lueck at web.de
Wed Jul 7 14:34:19 CEST 2010
Brandon Kuczenski <brandon at 301south.net>, 07.07.2010 13:58:08:
>Say I have a macro \mymacro which expands to a number, like
>'0.00346'. Due to circumstances beyond my control, this macro sometimes
>contains something unsightly, like '3.46e-03', which causes later commands
>(in fp.sty) to barf.
>
>Is there a way I can detect an 'e' in a macro expansion?
1. see substr.sty,
http://ctan.org/pkg/substr,
some enhanced documentation is
http://tug.ctan.org/tex-archive/macros/latex/contrib/nicetext/demo/substr.pdf
2. with LaTeX internals \in@, \ifin@:
\expandafter\in@\expandafter e\expandafter{\mymacro}
\ifin at ...\else...\fi
... these tests are not expandable
(so, e.g., they will break inside section titles going to TOC),
essentially (?--I would like to find the time to decide reliably)
due to the fact that these macros serve to test for *arbitrary* substrings.
Testing for a *fixed* substring like `e' can be done expandably.
Do you need this?
3. The coolstr package
http://ctan.org/pkg/coolstr
serves more general purposes regarding numbers.
HTH -- Uwe.
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