Re: Help: Regular expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg123070] Re: Help: Regular expressions
• From: "Oleksandr Rasputinov" <oleksandr_rasputinov at hmamail.com>
• Date: Tue, 22 Nov 2011 05:36:25 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <jad600\$eig\$1@smc.vnet.net>

```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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