Péter Szilágyi wrote:
does boost or does it not contain the unordered_map,
Boost doesn't currently have unordered containers. I'm going to ask for a review soon, but given the amount of time it's taken libraries to get into boost recently, don't hold your breath. The review won't be for a while and, if it's accepted, it'll have to wait for an appropriate release to be included. For now, you can get the work in progress from: http://boost-consulting.com/vault/index.php?directory=Containers It's called 'unordered.tar.gz'. It should be pretty reliable.
then anyone has any idea how I could use the boost hash class with the VC++ (2005) hash_map class?
Looking at the MSDN documentation, boost::hash will have a couple of issues with Visual C++'s hash_map. One is that Visual C++'s hash_map uses power of 2 sized buckets - while boost::hash is really designed to work with a container that uses a prime number of buckets. So if your key's hash values don't vary much in the lower bits you'll get a lot of collisions. Whether this is likely depends on your data, but you'll need to be careful. The other issue is that while unordered_map uses an equality predicate to compare elements, Visual C++'s hash_map uses a 'less' predicate. Although, as long as the comparison is consistent with the hash value I think it should be okay. But if you do want to use Boost.Hash, then you'll need to implement your own hash_compare which uses boost::hash. Here's a sketch of how this might be done - although, completely untested, as I'm using Linux at the moment. template<class Key> class my_hash_compare { boost::hash<Key> hasher_; public: const std::size_t bucket_size = 4; const std::size_t min_buckets = 8; hash_compare() : hasher_() {} std::size_t operator()(const Key& k) const { return hasher_(k); } bool operator()(const Key& k1, const Key& k2) const { return k1 < k2; } }; stdext::hash_map<std::string, int, my_hash_compare<std::string> > map; For more info on hash_compare see: http://msdn2.microsoft.com/en-us/library/8zz3703d(VS.80).aspx Hope that helps, Daniel