On 5/13/11 1:01 PM, Timon Gehr wrote:
On 5/13/11 3:25 AM, Timon Gehr wrote:
On p368 the CheckedInt struct does not check for overflow in the unary minus
operator.
Unary minus never overflows. That being said, there is the oddity that
-x is x when x == int.min. Even in that case there is no loss of
information.
Andrei
This behavior is caused by _overflow_ when the error condition that is checked
in
++ is overflow:
auto x=CheckedInt(int.min);
x=-x; //passes
x=~x;
x++;//throws
Not sure I understand the point here. I do agree that this may be
confusing and also that it's reasonable to check against int.min in
unary minus.
Also, the statement that there is no loss of information is just wrong:
scanf("%d %d %d",&n_,&m_);
auto n=CheckedInt!int(n_),m=CheckedInt!int(m_);
enforce(n>0&& m<0, "provide meaningful input!");
foreach(i;0..n) m=-m;
writeln(n," is"~(m<0?"odd":"even")); //disaster strikes!
Depends on how one defines "information". I meant it simply as state
available to the program.
Andrei
