Re: Exception Handling

[Jeff Carter <jrcarter@acm.org>]

Preben Randhol wrote:
> One slightly different angle though. Say you have made a program that
> expects the user to input a value. It could be any value so it should be
> possible to enter 2.3E-4 etc...
> 
> Would it be OK to trap an erronious entry (like "2.3W-4") with an
> exception or would you make an extra check before trying to convert the
> string to a float (or the appropriate class).

Ada provides at least 2 ways to check that a string contains an
appropriate representation of a floating-point number: 'Value and
Ada.Text_IO.Float_IO. Both convert the string to a floating-point value
and signal an invalid string by raising an exception. Whether you agree
that raising an exception is appropriate, why would you write another
subprogram to parse a string for a floating-point value when you can
reuse these existing, robust, and well-tested subprograms?

-- 
Jeff Carter
"Now go away or I shall taunt you a second time."
Monty Python & the Holy Grail