> On Jan 19, 2016, at 10:11 AM, Aandi Inston <aa...@quite.com> wrote:
>
> Thank you. The problem turned out to be a foolish mistake in the caller,
> but this has alerted me to the need for a systematic check of the
> conversion between BOOL and C integers.
The only thing likely to cause problems is if values other than 0 or 1 get
assigned to a bool or BOOL, specifically values > 255. For example if you
assign 256 to a BOOL it may end up as 0. This can happen if you refactor
something like
if (count)
doSomething();
into
BOOL shouldDoSomething = (count);
…
if (shouldDoSomething)
doSomething();
Depending on the value of `count`, this can cause an overflow in the BOOL
variable and give it an incorrect false value. The fix is to change the
assignment to `(count != 0)`.
That being said, any Cocoa method that returns BOOL should be trustable to
return only NO (0) or YES (1), so there shouldn’t be a need to do any extra
checks on conversions.
—Jens
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