From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,eee47022b0e39dbb
X-Google-Attributes: gid103376,public
From: JohnVolan@macconnect.com (John Volan)
Subject: Re: Exception problem
Date: 1997/03/09
Message-ID: <JohnVolan-0903971008050001@accs-as34-dp04.snfc.grid.net>#1/1
X-Deja-AN: 224217591
References: <330A0D25.313@fs2.assist.uci.edu>
 <evans-2202972108360001@ppp1.s8.pgh.net> <3311BFC4.7576@fs2.assist.uci.edu>
 <5eutjo$rlg@ash.ridgecrest.ca.us>
Organization: None
Newsgroups: comp.lang.ada
Date: 1997-03-09T00:00:00+00:00
List-Id: <comp.lang.ada>


> I would have written the program almost exactly the way you did.  The 
> only difference is that I would have used "Get_Line(TEXT, LENGTH);" 
> instead of Get.  That would have eliminated the need for the Skip_Line.
> 
> After obtaining the text from the user, I would have used the 'VALUE 
> attribute to convert TEXT(1 .. LENGTH) to the integer type, if possible.  
> The 'VALUE attribute will raise an exception if the text string isn't an 
> integer, so you would have no choice but to use an exception handler.

The disadvantage in using 'Value is that it is not very forgiving if the
input is not *exactly* an integer literal, i.e., if there is white space
before and/or after the integer literal within the input string. An
alternative method is to go ahead and read the input line into a string
buffer, but then use a Get procedure from an instantiation of
Ada.Text_IO.Integer_IO:

    Get (Text, Length);
    Get (From => Text (1 .. Length), -- eats any leading whitespace
         Item => Your_Integer,
         Last => Next); -- stops at the end of the integer literal,
                        -- before any trailing whitespace (or indeed,
                        -- any trailing anything
    -- optionally, if you want to do something with the rest of the input line,
    -- you can do:
    Next := Next + 1;
    -- and then do further processing on Text (Next .. Length)
> I would have written the program almost exactly the way you did.  The 
> only difference is that I would have used "Get_Line(TEXT, LENGTH);" 
> instead of Get.  That would have eliminated the need for the Skip_Line.
> 
> After obtaining the text from the user, I would have used the 'VALUE 
> attribute to convert TEXT(1 .. LENGTH) to the integer type, if possible.  
> The 'VALUE attribute will raise an exception if the text string isn't an 
> integer, so you would have no choice but to use an exception handler.

The disadvantage in using 'Value is that it is not very forgiving if the
input is not *exactly* an integer literal, i.e., if there is white space
before and/or after the integer literal within the input string. An
alternative method is to go ahead and read the input line into a string
buffer, but then use a Get procedure from an instantiation of
Ada.Text_IO.Integer_IO:

    Get (Text, Length);
    Get (From => Text (1 .. Length), -- eats any leading whitespace
         Item => Your_Integer,
         Last => Next); -- stops at the end of the integer literal,
                        -- before any trailing whitespace (or indeed,
                        -- any trailing anything
    -- optionally, if you want to do something with the rest of the input line,
    -- you can do:
    Next := Next + 1;
    -- and then do further processing on Text (Next .. Length)

----------------------------------------------------------------------
Internet.Usenet.Put_Signature 
  (Name => "John G. Volan", Home_Email => "johnvolan@macconnect.com",
   Slogan => "Ada95: The World's *FIRST* International-Standard OOPL",
   Disclaimer => "No one ever defined these opinions, so using them" 
     & "is totally erroneous...or is that a bounded error now? :-) ");
----------------------------------------------------------------------