Re: Need Help On Ada95 Problem

[Shark8 <onewingedshark@gmail.com>]

On Feb 9, 7:36 pm, BrianG <m...@null.email> wrote:
> On 02/08/2012 09:01 PM, Shark8 wrote:
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> > On Feb 8, 7:03 pm, Will<willmann...@gmail.com>  wrote:
> >> I am new to Ada and need help on an exercise for school.  Can anyone
> >> help.  The problem is as follows ( you can skip all the build up
> >> background A Christmas Story references):
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> >> Problem 1: Secret Decoder Ring
> ...
> >>       number wheel ->      0  1  2  3  4  5  6  7  8  9
> >>       letter wheel ->      U  R  O  V  A  L  T  I  N  E
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> >> So, for example, Randy encrypts the PIN 9537 as ELVI.
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> >> Complete the function Encrypt(PIN) that takes a 4-digit PIN (as a
> >> string) and returns the corresponding 4-letter code (also as a
> >> string).
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> >> Note: It would be possible to convert digits to letters using a giant
> >> IF statement, but don't do this. Instead, the letter wheel is given to
> >> you as a string, so use each digit to read the appropriate letter from
> >> the string.
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> > Alright this is actually a simple problem; there are several ways to
> > go about this,
> > but let's play to Ada's strengths and use types.
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> ...
> > Reading the problem the note says:
> > It would be possible to convert digits to letters using a giant
> > IF statement, but don't do this. Instead, the letter wheel is given to
> > you as a string, so use each digit to read the appropriate letter from
> > the string.
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> > Meaning that they're hinting strongly that you use the CASE statement.
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> I don't see why this would require either an if or a case.
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> --
> ---
> BrianG
> 000
> @[Google's email domain]
> .com

Well, you COULD use Ada's Maps; but that's just going to do the same
thing: you still have to define the mapping.
You can't just index into Character (via 'POS, 'VAL and index-
manipulation) because the mapping isn't sequential;
or even partly-sequential in the ASCII codes.

See the (3,4,5) association with (V,A,L) and (6,7,8) with (T,I,N).