msvcp60: Avoid signed-unsigned integer comparisons
Max TenEyck Woodbury
max at mtew.isa-geek.net
Sun Mar 10 09:24:46 CDT 2013
On 03/10/2013 07:00 AM, Henri Verbeet wrote:
> On 10 March 2013 08:20, larmbr zhan <nasa4836 at gmail.com> wrote:
>> But It behaves different when it is signed or not. According to
>> C Standard,
>> - For the signed case, once it overflows, resulting in
>> representing a negative value .
> Actually, signed overflow behavior is undefined according to the
Specifically, some hardware throws an exception on signed arithmetic
overflow and C is specifically designed to be hardware independent, so
it has to be 'undefined behavior'.
>> - For the unsigned case, once it overflows, resulting in
>> representing a value reduced modulo the largest value
>> that object could hold.
Nit: modulo the largest value the object can hold _plus one_, but it
should be treated as another 'undefined behavior'.
To further complicate the issue, while size_t is always unsigned, size_t
can be 16, 18, 32, 36 or 64 bits and still be compliant. So use
'size_t' when you are talking about the size of something, and
'unsigned' for flag sets and counts.
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