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Re: [Scheme-reports] digit-value
On Sun, Jul 01, 2012 at 08:26:24PM -0400, John Cowan wrote:
> Peter Bex scripsit:
> > Alternatively, change it to accept just the ASCII number characters,
> > and possibly with Marc's suggestion of accepting digits in any base
> > (and perhaps an optional second argument to specify which base we're
> > working in). That would really be useful, since that could be used
> > to implement very common char->number conversion and could even be
> > used internally in string->number (at least conceptually).
> It's quite common (though technically not portable) to determine that a
> character is a digit using `char-numeric?` and then determine its value
> using `(- (char->integer x) (char->integer #\0))` or the equivalent.
Code that does this will very often also contain code that does
something similar for hex-digits.
"The process of preparing programs for a digital computer
is especially attractive, not only because it can be economically
and scientifically rewarding, but also because it can be an aesthetic
experience much like composing poetry or music."
-- Donald Knuth
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