On Wednesday 02 of January 2013 16:00:50 you wrote:
> > I wanted to prohibit user to assign negative value to a variable.
> > This variable is later passed to a recurrence function as
> > argument and of course I got segmentation fault, because
> > the function is called 4294967291 times.
>
> I guess you mean recursive function. (Isn't English fun? Hang in there.)
Yes, you are right.
[...]
> This took me a couple of years to figure out, but unsigned types are
> not for enforcing range. They are strictly for optimization. For
> example (in C, not C++):
>
> int doorway( int p1, int * result )
> {
> /* Note that this constant upper limit is not necessarily SHRT_MAX
> from limits.h */
> if ( ( p1 < 0 ) || ( p1 > 0x7fff ) )
> { return BAD_RANGE;
> }
> * result = recurse( (unsigned short) p1 )
> ...
> return GOOD_RANGE;
> }
>
> unsigned short recurse( unsigned short p1 )
> {
> ...
> intermediate = recurse( /* some expression that never goes
> negative or exceeds USHRT_MAX */ );
> ...
> }
Thank you very much again for sharing your knowledge.
> Have fun!
>
> --
> Joel Rees
Zbigniew
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