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Re: Help: Regular expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123085] Re: Help: Regular expressions
  • From: James Stein <mathgroup at stein.org>
  • Date: Wed, 23 Nov 2011 07:04:24 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <jad600$eig$1@smc.vnet.net> <201111221036.FAA28079@smc.vnet.net>

<oleksandr_rasputinov at hmamail.com> wrote:

> If you find regular expressions opaque and difficult to work with (and who
> doesn't?) then you might be better off using Mathematica's string pattern
> syntax instead.


Yes, I've been using regular expressions (infrequently ) for decades, and
usually must resort to  a reference to do what I wish. For people with
MacIntosh computers, the free text editor "TextWrangler" comes bundled with
a manual with one or two clear chapters on regular expressions.


On Tue, Nov 22, 2011 at 2:36 AM, Oleksandr Rasputinov <
oleksandr_rasputinov at hmamail.com> wrote:

> On Mon, 21 Nov 2011 09:34:56 -0000, Shizu <slivo.vitz at msa.hinet.net>
> wrote:
>
> > Hello,
> >
> >     Would anybody tell me what's the difference between these two --
> > with amd without "^"?
> >     Regular expressions are not easy for me!
> >
> >
> > In= StringSplit["line1\nline2\nline3", RegularExpression["(?m)^"]] //
> > InputForm
> >
> > Out= {"line1\n", "line2\n", "line3"}
> >
> > In= StringSplit["line1\nline2\nline3", RegularExpression["(?m)"]] //
> > InputForm
> >
> > Out= {"l", "i", "n", "e", "1", "\n", "l", "i", "n", "e", "2", "\n", "l",
> > "i",
> >  "n", "e", "3"}
> >
> >     Thanks in advance.
> >
>
> The difference is that the latter is equivalent to
>
> StringSplit["line1\nline2\nline3", RegularExpression[""]]
>
> since (?m) is just an option which makes ^ match line beginnings rather
> than the beginning of the string as a whole.
>
> If you find regular expressions opaque and difficult to work with (and who
> doesn't?) then you might be better off using Mathematica's string pattern
> syntax instead.
>
>


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