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Re: Help: Regular expressions

On Mon, 21 Nov 2011 09:34:56 -0000, Shizu <slivo.vitz at> 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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