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From: "Steve" <nospam_steved94@comcast.net>
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References: <m31x3b6n5v.fsf@rr.trudgett>
Subject: Re: String filtering
Date: Tue, 27 Sep 2005 18:54:54 -0700
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Date: 2005-09-27T18:54:54-07:00
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"David Trudgett" <wpower@zeta.org.au.nospamplease> wrote in message 
news:m31x3b6n5v.fsf@rr.trudgett...
>
> Hi all,
>
> I've been puzzling for a little bit over a good way to filter out
> unwanted characters from a string. In particular, I have an unbounded
> string and want to filter out of it all characters not in 'a'..'z',
> 'A'..'Z', '0'..'9'. So far I've only thought of tedious ways to do
> it. Is there an easy way to do it using the string handling facilities
> in Ada? I think I almost got there with the idea of using
> Maps.Character_Set, and so on, but I haven't quite pieced it together
> yet.
>
> Thanks.
>
> David
>

If you're just looking for simple code, I would suggest using the Index and 
Delete functions in Ada.Strings.Unbounded.  Something along the lines of:

  loop
      deleteIndex := Index( source, charSet, test => outside );
      exit when deleteIndex = 0;
      Delete( source, deleteIndex );
  end loop;

It's not very efficient, but I think it is about as simple as you can get. 
You can probably use Find_Token to get rid of consecutive chunks of 
characters you want to remove, but it would be a little bit more messy (and 
efficient).

Steve
(The Duck)


> -- 
>
> David Trudgett
> http://www.zeta.org.au/~wpower/
>
> We must learn to live together as brothers or perish together as
> fools.
>
>    -- Martin Luther King, Jr.
>