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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: How to shuffle/jumble letters of a given word?
Date: Sun, 28 Jun 2015 22:07:49 +0100
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Date: 2015-06-28T22:07:49+01:00
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Trish Cayetano <trishacayetano@gmail.com> writes:

> I am creating a "text twist game" where you guess the words in a
> jumbled manner. How do I set the code to shuffle the letters?
>
> Example: word to be guessed is HELLO
>
> What should be displayed is: LOLEH or LELHO

You want to take the letters in a random order, so you'll find
Ada.Numerics.Float_Random[1] useful.

You can't just take the random'th character of the original string,
because you mustn't take the same character twice.

One (possibly heavyweight) approach would be to create a new type
containing a float and a character,

   type Item is record
      Key : Float;
      Ch  : Character;
   end record;

and a type for an array of Items, rather like the String you want to
jumble,

   type Elements is array (Positive range <>) of Item;

and then instantiate Ada.Containers.Generic_Array_Sort[2] for Elements.
You'll need a function "<" to compare two Items on the basis of their
Keys, e.g.

   function "<" (L, R : Item) return Boolean is (L.Key < R.Key);

Then, given a String, create an Elements array with each Key a new
random number and each Ch the corresponding character in the String;
sort it (which, since the Keys were random, is effectively a shuffle);
and return a String formed of the Chs in their new order.

[1] http://www.ada-auth.org/standards/12rm/html/RM-A-5-2.html
[2] http://www.ada-auth.org/standards/12rm/html/RM-A-18-26.html#p2