Re: Subtypes with Combined Ranges

[lutz@iks-jena.de (Lutz Donnerhacke)]

* David Rasmussen wrote:
>6.1 Write a program to count the number of occurrences of each letter of
>    the alphabet typed as input at the keyboard. Using a subtype of
>    Character as the index subtype of an array is a sensible way to do
>    this.

>My first thought was to do this:
>subtype Alphabetical is Character range 'A'..'Z' | 'a'..'z';

A subtype has to be holefree.

>But I get an error. What is the best type for this excercise?

There are multiple solutions:
  - subtype Uppercase is Character range 'A' .. 'Z';
    subtype Lowercase is Character range 'a' .. 'z';
  - lettertest : array (Character) of Boolean :=
      ('A' .. 'Z' | 'a' .. 'z' => True, others => False);
  - lettermap : Ada.Strings.Maps.Character_Set :=
      To_Set (((Low => 'a', High => 'z'), (Low => 'A', High => 'Z')));
  - and many more.

Because you post your exercise here, you will get an other one:
 Implement at least ten different algorithms which print the elementary
 multiplication table. Post them here in two weeks.