regular expression : the dollar sign ($) work with re.match() or re.search() ？

[iMath]

I only know the dollar sign ($) will match a pattern from the
end of a string,but which method does it work with ,re.match() or re.search() ？

[Jussi Piitulainen]

iMath writes:

> I only know the dollar sign ($) will match a pattern from the end of

> a string, but which method does it work with, re.match() or
> re.search()

It works with both. With re.match, the pattern has to match at the
start of the string _and_ the $ has to match the end of the string (or
a line); re.search scans the string until it finds a suitable start.

What was the weird character that you used as a question mark? I
removed them because they confuse the newsreader I use.

[Chris Angelico]

On Wed, Sep 26, 2012 at 5:48 PM, Jussi Piitulainen
<jpii...@ling.helsinki.fi> wrote:
> What was the weird character that you used as a question mark? I
> removed them because they confuse the newsreader I use.

It appears to be Unicode Character 'FULLWIDTH QUESTION MARK' (U+FF1F).
Normally I'd be inclined to simply use U+003F instead, but hey, it's a
question mark still.

ChrisA

[Peter Otten]

Why not try it out in the interactive interpreter? Here's the "deluxe
version":

>>> def demo(pattern="mid$", texts=["start mid end", "start mid", "mid end",
"mid"], matchers=[re.match, re.search]):
... print "pattern:", pattern
... for text in texts:
... for matcher in matchers:
... name = matcher.__name__
... print u"\N{CHECK MARK}" + name if matcher(pattern,
text) else (" "*(len(name)+1)),
... print repr(text)
...
>>> demo()
pattern: mid$
'start mid end'
✓search 'start mid'
'mid end'
✓match ✓search 'mid'

[Alister]

It shows fine in my news reader, perhaps you should consider changing to
one that works properly (btw I am using pan on a fedora 17 netbook)



--
Q: Why is Microsoft's Product Support a failure?
A: Because Microsoft needs a Support Group instead.

[Jussi Piitulainen]

Alister writes:
> On Wed, 26 Sep 2012 10:48:00 +0300, Jussi Piitulainen wrote:
>
> > iMath writes:
> >
> >> I only know the dollar sign ($) will match a pattern from the end
> >> of a string, but which method does it work with, re.match() or
> >> re.search()
> >
> > It works with both. With re.match, the pattern has to match at the
> > start of the string _and_ the $ has to match the end of the string
> > (or a line); re.search scans the string until it finds a suitable
> > start.
> >
> > What was the weird character that you used as a question mark? I
> > removed them because they confuse the newsreader I use.
>
> It shows fine in my news reader, perhaps you should consider changing to
> one that works properly (btw I am using pan on a fedora 17 netbook)

I was just curious why anyone would use anything other than the ASCII
question mark as an ordinary question mark when writing in English in
a newsgroup.

The post had this:

0000520 61 72 63 68 28 29 20 20 ef bc 9f 0a
a r c h ( ) sp sp o < us nl

od is showing (ef bc 9f) as (o < us) but since they are not individual
characters anyway, never mind that. Google tells me (ef bc 9f) is
UTF-8 for U+FF1F FULLWIDTH QUESTION MARK, so now I basically have my
answer as to what it is, though still not as to why one would use it.

The ordinary question mark would look like this:

0000000 61 72 63 68 28 29 20 3f 0a
a r c h ( ) sp ? nl

[Prasad, Ramit]

iMath wrote:
> Sent: Wednesday, September 26, 2012 2:39 AM
> To: pytho...@python.org
> Subject: regular expression : the dollar sign ($) work with re.match() or re.search() ？

>
> I only know the dollar sign ($) will match a pattern from the
> end of a string,but which method does it work with ,re.match() or re.search() ？

You can try this on the interactive interpreter.
>>> re.match('hi$', 'xihi')
>>> re.search('hi$', 'xihi')
<_sre.SRE_Match object at 0x13FF7100>

Although, I think match does not work since match
only starts searching at the start of the string
while search looks for the pattern anywhere in the string.

>>> re.match('x.hi$', 'xihi')
<_sre.SRE_Match object at 0x15693BF0>

I guess you can consider re.match's pattern to be
prefixed with '^'.

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[Ian Kelly]

On Fri, Sep 28, 2012 at 12:07 PM, Prasad, Ramit
<ramit....@jpmorgan.com> wrote:
> I guess you can consider re.match's pattern to be
> prefixed with '^'.

You can in this case, but they're not equivalent in multi-line mode:

>>> re.match('^two', 'one\ntwo', re.M)
>>> re.search('^two', 'one\ntwo', re.M)
<_sre.SRE_Match object at 0x0475BFA8>

[iMath]

在 2012年9月26日星期三UTC+8下午3时38分50秒，iMath写道：

> I only know the dollar sign ($) will match a pattern from the
>
> end of a string,but which method does it work with ,re.match() or re.search() ？

I thought re.match('h.$', 'hbxihi') will match ‘hi’ ,but it does not .so why ?

[Steven D'Aprano]

re.match only matches at the *start* of the string, so "h.$" tries to
match:

* start of string
* literal h
* any character
* end of string


You want re.search, which will search the entire string and match "hi" at
the end of the string.


--
Steven