Re: String slicing.

[sk <noname@myob.com>]

Hi,

If you are using Gnat, type "gnatpsta" at the command-line and
you will be provided the following :

   type Integer is range -(2 ** 31) .. +(2 ** 31 - 1);

   subtype Natural  is Integer range 0 .. +(2 ** 31 - 1);
   subtype Positive is Integer range 1 .. +(2 ** 31 - 1);

   ...

   type String is array (Positive range <>) of Character;
   pragma Pack
(String);                                                        

So in the simplest terms, a string is a numerically indexed
array of characters.


declare
    -- SB, SE --> String_Begins, String_Ends
    SB, SE : Natural := 0;
    Sample_String : constant String := "Hello Cruel World";

begin
    -- Find first ' '
    for i in Sample_String'Range loop
        if Sample_String (I) = ' ' then
             SB := i;
             exit;
        end if;
    end loop;

    ...
    -- Pretend that the second ' ' has been found.

    TIO.Put_Line (
        "The World is such a " &
        Sample_String (SB .. SE) &
        " place."
     );

end;

In general, unless you are searching for control characters,
specify them in the source or use named characters.

For example,

    Html_Tag_Open  : constant Character := '<';
    Html_Tag_Close : constant Character := '>';

    Horizontal_Tab : constant Character :=
        Ada.Characters.Latin_1.HT;

Also, you don't need to introduce the heavy-weight 
Ada.Strings.xxx unless your application is more
complex than the one above. Even then, I personally
just write small string-searchers within the application
rather than introduce the Ada.Strings.xxx

Hope this helps.

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