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From: sjw <simon.j.wright@mac.com>
Newsgroups: comp.lang.ada
Subject: Re: unsigned type
Date: Sat, 11 Jul 2009 10:18:34 -0700 (PDT)
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Date: 2009-07-11T10:18:34-07:00
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On Jul 11, 3:40=A0pm, Hibou57 (Yannick Duch=EAne)
<yannick_duch...@yahoo.fr> wrote:

> The length of a string is Natural, the index type Positive, as long as
> lowest bound is 1.

The index type of String is always positive!

> Printing a zero length string does not imply attempting to print
> chracters in index range 1 .. 0, but may be instead properly handled
> by simple not accessing the string and simply not printing anything,
> providing the length has been previously known to be zero.

I think this is too restrictive!

This:

with Ada.Text_IO; use Ada.Text_IO;
procedure Zero_Length_String is
   S : String (-5 .. -7) :=3D "";
begin
   Put_Line ("S is """
               & S
               & """, 'First is "
               & Integer'Image (S'First)
               & ", 'Last is "
               & Integer'Image (S'Last));
   Put_Line ("S is """ & S (S'First .. S'Last) & """");
end Zero_Length_String;

results (GNAT GPL 2009) in

$ ./zero_length_string
S is "", 'First is -5, 'Last is -7
S is ""