On Sun, 17 Jul 2005, Servando Garcia wrote:
> Using regular expressions how do I represent Floats.
Hi Servando,
I know that you're working on a parser project, but the regex for doing
floats is pretty much a homework project. There's not much we can do
except point you toward the Regular Expression HOWTO tutorial page:
http://www.amk.ca/python/howto/regex/
I'd also strongly recommend that you look at the documentation in the
Python Standard Library, as it does have concrete examples on how to
recognize things like floats here:
http://www.python.org/doc/lib/node117.html
Your question is also context-sensitive: what a floating point number
looks like really depends on what kind of language we're modeling.
As a concrete example, in the ML family of languages:
.42
is not a floating-point literal, although it is one in Python, because
it's missing a leading decimal digit. Conversely, in the Ruby language,
123_456.789
is a floating point literal, although it isn't one in Python, because
Python doesn't allow underscores. I guess I'm trying to say: some lexical
conventions are not universal: otherwise, things would be too easy.
*grin*
You can't assume that everyone uses the same notation for floating point
literals: you need to show examples of what you consider to be floats.
If you want to see Python's specification for floating point literals,
see:
http://www.python.org/doc/ref/floating.html
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