Re: Exception problem

[rodemann@mathematik.uni-ulm.de (Joerg Rodemann)]

Larry Coon (larry@fs2.assist.uci.edu) wrote:
>       begin
>          Put ("Enter a positive number: ");
>          Get (X);
>          exit; -- No exception, so input was valid.
>       exception
>          when Constraint_Error =>
>             Put_Line ("Entry must be positive.  Try again.");
>          when Data_Error =>
>             Put_Line ("Entry must be a number.  Try again.");
>       end;

> This code handles non-positive numeric input (eg: 0 or -3) correctly.  
> But when I give it non-numeric input (eg: C), it displays the "Entry 
> must be a number.  Try again" message repeatedly and never stops for 
> input again.

It seems to me your problem is that Get checks for validity of the data by 
raises the Data_Error exception already before any characters are removed 
from the input buffer. Therefore the token leading to Data_Error will be 
processed during the next Get in the same way as before. 

Although I do not have the ARM at hand I think a Flush(Standard_Input) might 
solve this situation.

Hope this helps

Greetings

George

--
Joerg 'George' Rodemann                      Erhard-Groezinger-Strasse 82
Department of Physics                                   D-89134 Blaustein
University of Ulm                                      Tel. (0731) 553319
e-mail:                                    rodemann@mathematik.uni-ulm.de