Re: [Boost-users] seed for hash

Rares Vernica wrote:

Hi,

Does the hash function uses a seed?

If a call: boost::hash<std::string> string_hash; std::size_t h = string_hash("Hash me");

and then after a year I call again: string_hash("Hash me");

Does it return the same value?

Yes; a hash is a (pure, deterministic) function of its input value, i.e., a function in the mathematical sense as well as the C++ sense. Any hash must satisfy that property or algorithms using it will behave in rather strange/unpredictable ways. -- James