STL Hash Functions

Does the STL have any Hash functions available, that are exposed publicly?

I know that there are some non-standard implementati开发者_JS百科ons that use hash values (such as boost::hash_map), and MSVC8 implements a version of the hash_map/hash_set/etc.

But are there any Hash Functions that are defined in the C++98 STL?

If not, what are the best non-C++98 sources of a reliable hash function?

Order of preferred sources (from most acceptable to least): Boost, C++0x standard STL, TR1, other 3rd party.

to summarize:

• The STL has hash functions
• The C++98 standard library does not
• The C++ TR1 has hash functions (6.3.3[tr.unord.hash])
• boost has hash functions
• The C++11 standard library has hash functions (20.8.12[unord.hash])

And all of them are designed for hashed associative containers, not for cryptography.

I guess you're looking for hash functions for hash tables, not for cryptography, correct?

In that case, what about boost::hash?

The documentation says it's compatible with the TR1 hash, which should become part of the upcoming C++0x standard. That means it's probably already found in quite a few compilers.

For cryptographic hashes, there seems to be a SHA-1 implementation in Boost, but the way to go if you need them heavyweight is to use a dedicated library, such as Crypto++.

The choice of Hash function ideally depends on your use for the results. I suspect this may partly be due to the idea "one size does not fit all".