Re: Exception problem

[JohnVolan@macconnect.com (John Volan)]

> 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)

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  (Name => "John G. Volan", Home_Email => "johnvolan@macconnect.com",
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     & "is totally erroneous...or is that a bounded error now? :-) ");
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