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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Substrings as argument to procedures/functions
Date: Tue, 12 Apr 2016 11:01:35 +0200
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Date: 2016-04-12T11:01:35+02:00
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On 12/04/2016 10:25, reinkor wrote:

> I believed that if a substring is an argument to a subroutine,
> then its "range" would start at 1 (and not inherited from the calling program).
> But this seems not to be the case.
>
> Given the following Ada source code:
>
> with Text_IO;
> use  Text_IO;
> procedure t3 is
>     package Int_Io is new Text_IO.Integer_Io (Integer);
>     use Int_Io;
>     procedure string_test1(S : String) is
>     begin
>        New_Line;
>        Put(" In string_test1: ");
>        Put(S'First,4);
>        Put(S'Last,4);
>     end string_test1;
>     Str : String := "ABCDEF";
> begin
>        string_test1(Str);
>        string_test1(Str(3..5));
> end t3;
>
> The second call to "string_test1" gives:
>
>   In string_test1:    3   5
>
> (at least on my computer).
>
> Is this correct? And in case, is it "good" ? :-)

Yes, it is good.

Consider a program that uses an index to walk through a string/array. 
When you pass a substring of the string and an index into it (usually 
in-out) down to a subprogram, then the index remains valid.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de