From: Chad Perrin <code@...>
Date: 2011-05-11T06:19:49+09:00
Subject: Re: Generate random string matching specific pattern and length

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On Wed, May 11, 2011 at 05:56:02AM +0900, Kevin wrote:
> I'm trying to generate a random set of strings to fill a database with th=
at
> match the following pattern:  /^([A-Z]|[a-z]|-)+$/
>=20
> The array I'm trying to create must contain strings that look like
> "A12-34-4567" and be exactly ten characters long I have seen code on the
> internet for generating random strings but I don't have internet at home =
at
> the moment to really study examples like the one here:
> http://coderrr.wordpress.com/2008/10/28/ruby-golf-generating-random-strin=
gs
>=20
> I'm guessing that something like map { if  /^([A-Z]|[a-z]|-)+$/  &
> char.len=3D=3D10
>   strings<< current_matching_value
> }
>=20
> would achieve the right solution.  Any pointers would be greatly
> appreciated.

There's probably something like a thousand ways to achieve that.  By th
eway, it looks like you missed a character class -- numbers.  Your regex
should probably have been something like this:

    /^([A-Z]|[a-z]|\d|-)+$/

In fact, if it should be exactly ten characters long, you might want that
regex to look like this:

    /^([A-Z]|[a-z]|\d|-){10}$/

If you want to create strings that contain random distributions of
characters from a list of possible characters, you could use an array:

    foo =3D (
      ('A'..'Z').to_a << ('a'..'z').to_a << ('0'..'9').to_a << '-'
    ).flatten
    bar =3D String.new
    10.times { bar << foo.shuffle[0] }

Now . . . if you specifically want dashes at specific places in your
string (which I suspect you might), that changes things.

--=20
Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]

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