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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Length of unbounded_string.
Date: Sun, 16 Oct 2011 11:59:38 +0200
Organization: Tidorum Ltd
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Date: 2011-10-16T11:59:38+02:00
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On 11-10-16 10:48 , ldries46 wrote:
> In my program I use unbounded_string str
>
> I want to change the last character of the string using the program lines
>
> 2205 len := Length(str);
> 2206 Replace_Slice(str, len, len, "G");

Similar code works for me (debian, gnat).

It seems to me that code like the above can fail with Constraint_Error 
only if str is the null string, in which case len = 0, which causes a 
Constraint_Error in the call because the 2nd parameter of Replace_Slice 
is of subtype Positive.

> Then I get the following message printed in my exception part of the
> program
   ...
> Original line : /* GtkPrintJob
   ...
> In this print out the Original line represents "str".

Are you certain that your "str" is really that, and is not a null 
string? I would put a check in the code, before the call of 
Replace_Slice, and not trust the exception messages.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .