Re: test if a string is a valid 'number'?

From:

"Ashot Geodakov" <a_geodakov@nospam.hotmail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 31 May 2007 08:44:35 -0700

Message-ID:

<OwvLbq5oHHA.5032@TK2MSFTNGP02.phx.gbl>

class MyException
{
public:
  enum { BadSign, IllegalDigit, SoOn } m_type;
};

try
{
.. do stuff
}
catch( MyException* e )
{
   switch( e->type )
   {
    case MyException::BadSign:
      ..message about bad sign.
      break;
   }
   delete e;
}

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:33jt53tirdrl3tb7t7r6m9blu1tfg1o61k@4ax.com...

I'm not sure of the correlation here between the example you gave and the
example I gave,
but yes, had I chosen that particular style of signaling an error, I would
use the
exception type so I could issue a meaningful error message. Otherwise,
the exceptions
would all end up reporting "Syntax error", which is not exactly
construable as a
user-friendly interface.
joe

On Wed, 30 May 2007 22:56:18 -0700, "Ashot Geodakov"
<a_geodakov@nospam.hotmail.com>
wrote:

I remember someone I worked with in the past, who loved to create a class
for each small task.

Instead of just

int a = 2 + 2;

he wrote:

class Sum
{
private:
int result;
public:
Sum( int a, int b ) : result( 0 ) { result = a + b; }
GetResult() { return result; }
};

So, SBadSignException, huh? Is it for the situation when the first
character
in the string is not a digit or "+" or "-"?

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:9gds53t23d6j8mhf1aei6ftnp1h09b0nro@4ax.com...

Whenever I want to throw exceptions to represent problems, I always
create
an abstract
superclass exception, e.g., CLexicalException, then I can derive
subclasses such as
CBadSignException, CIllegalDigitException, and so on. So the caller
knows
that any
exception thrown is always a member of the superclass, and could create
a
superclass catch
clause to capture the exception.
joe

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm