Re: [boost] Re: int vs. unsigned int

From: Wynand Winterbach (wynand_at_[hidden])
Date: 2003-10-30 10:54:56

Oh dear, I guess I'm blind and/or lazy :).

My didactic, pedantic super ego got the better of me.

--Wynand

On Fri, Oct 31, 2003 at 01:08:05AM +1100, Thorsten Ottosen wrote:
> "Wynand Winterbach" <wynand_at_[hidden]> wrote in message
> news:20031030154030.B9878_at_dip.sun.ac.za...
> > On Wed, Oct 29, 2003 at 10:13:14PM -0700, Dave Gomboc wrote:
> > > > so where should I use unsigned?
> > > >
> > > > -Thorsten
> > >
> > > Use unsigned numeric types whenever negative values aren't
> > > permitted or don't make sense.
> > >
> > > Dave
> > >
> >
> > I quote Bjarne Stroustrup (page 73, The C++ Programming Language, Third
> edition)
> 
> Actually, one of the to threads I mentioned was called "unsigned vs signed -
> Is Bjarne Mistaken?"
> 
> I believe the answer is "no".
> 
> > "The unsigned integer types are ideal for uses that treat storage as a bit
> array.
> > Using an unsigned instead of an int to gain one more bit to represent
> positive
> > integers is almost never a good idea. Attempts to ensure that some values
> are
> > positive by declaring variables unsigned will typically be defeated by the
> > implicit conversion rules"
> >
> > As an example that got me when I started programming, consider the
> following
> > seemingly innocuous case:
> >
> > char blah[6];
> >
> > for ( unsigned i = 5; i >= 0; i-- )
> >  {
> >   cout << blah[i];
> >  }
> >
> > This fails i can never become -1. Actually, you'll have an infinite loop.
> 
> there was a lot of similar examples in the threads.
> 
> -Thorsten
>