Re: [boost] [functional] boost::hash with 64-bit types

From: Daniel James (daniel_james_at_[hidden])
Date: 2006-03-20 17:21:18

Daniel James wrote:
> Peter Dimov wrote:
>> For larger integer types, we probably need something along the lines of
>>
>> std::size_t hash_value( val )
>> {
>>     size_t r = val;
>>
>>     while( val >>= size_t_bits )
>>     {
>>         hash_combine( r, (size_t)val );
>>     }
>>
>>     return r;
>> }
>>
>> It has the property of preserving the hash_value of all _values_ that can 
>> fit into a size_t, even though the underlying type is capable of holding 
>> bigger integers. 
> 
> I don't think it does.

Actually, it does for positive number. Sorry I misread it. What you were 
doing clicked a couple of seconds after I clicked on 'send'. But I'm not 
sure it works for negative numbers.
Daniel