String filtering

[David Trudgett <wpower@zeta.org.au.nospamplease>]

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

-- 

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.