about hash

[Christian Kreibich]

On Tue, 2002-12-31 at 06:14, Wang Shaofu wrote:
> Hi
> Looking for help!
> 
> hash_t HashKey::HashBytes(const void* bytes, int size) const
> 	{
> 	const unsigned char* cp = (const unsigned char*) bytes;
> 	hash_t h = 0;//unsigned int
> 
> 	for ( int i = 0; i < size; ++i )
> 		// Overflow is okay here.
> 		h = (h >> 31) + (h << 1) + cp[i];
>                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~This arithmetic make 
> sure there is no collision????

Hi, 

I'm not familiar with the rest of the HashKey class, but calculation of
a hash key as in this case doesn't take care of collisions -- they're
resolved later, when looking up an item in a hash table.

Cheers,
Christian.
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