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Groups > comp.lang.python > #74022
| Date | 2014-07-06 16:32 +0100 |
|---|---|
| From | MRAB <python@mrabarnett.plus.com> |
| Subject | Re: Question about metacharacter '*' |
| References | <3f7ecf04-b881-4e79-aa59-893580090468@googlegroups.com> <CABicbJKUOsKW77LGkDF-1E52AmsPpTJq=GAUTA2PLpff+7fxNQ@mail.gmail.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.11543.1404660755.18130.python-list@python.org> (permalink) |
On 2014-07-06 13:09, Devin Jeanpierre wrote: > On Sun, Jul 6, 2014 at 4:51 AM, <rxjwg98@gmail.com> wrote: >> Hi, >> >> I just begin to learn Python. I do not see the usefulness of '*' in its >> description below: >> >> >> >> >> The first metacharacter for repeating things that we'll look at is *. * doesn't >> match the literal character *; instead, it specifies that the previous character >> can be matched zero or more times, instead of exactly once. >> >> For example, ca*t will match ct (0 a characters), cat (1 a), caaat (3 a >> characters), and so forth. >> >> >> >> It has to be used with other search constraints? > > (BTW, this is a regexp question, not really a Python question per se.) > > That's usually when it's useful, yeah. For example, [0-9] matches any > of the characters 0 through 9. So to match a natural number written in > decimal form, we might use the regexp [0-9][0-9]*, which matches the > strings "1", "12", and "007", but not "" or "Jeffrey". > > Another useful one is `.*` -- `.` matches exactly one character, no > matter what that character is. So, `.*` matches any string at all. > Not quite. It won't match a '\n' unless the DOTALL flag is turned on. > The power of regexps stems from the ability to mix and match all of > the regexp pieces in pretty much any way you want. >
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Question about metacharacter '*' rxjwg98@gmail.com - 2014-07-06 04:51 -0700
Re: Question about metacharacter '*' Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-07-06 05:09 -0700
Re: Question about metacharacter '*' rxjwg98@gmail.com - 2014-07-07 11:51 -0700
Re: Question about metacharacter '*' Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-07-07 13:27 -0700
Re: Question about metacharacter '*' Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-07-07 22:50 +0100
Re: Question about metacharacter '*' MRAB <python@mrabarnett.plus.com> - 2014-07-06 16:32 +0100
Re: Question about metacharacter '*' Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-07-06 08:50 -0700
Re: Question about metacharacter '*' Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-06 09:24 -0700
Re: Question about metacharacter '*' Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-06 09:32 -0700
Re: Question about metacharacter '*' Roy Smith <roy@panix.com> - 2014-07-06 12:47 -0400
Re: Question about metacharacter '*' Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-06 10:38 -0700
Re: Question about metacharacter '*' Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-06 10:58 -0700
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