1, Rshashunsigned int rshash (const std::string& str) {unsigned int b = 378551; unsigned int a = 63689; unsigned int hash = 0; for (std::size_t i = 0; i < str.length (); i++) {hash = hash * a + str[i]; A = a * b; } return hash;}
2, Jshashunsigned int jshash (const std::string& str) {unsigned int hash = 1315423911; for (std::size_t i = 0; i < str.length (); i++) {hash ^= (hash << 5) + str[i] + (hash >> 2)); } return hash;}
3, Pjwhashunsigned int pjwhash (const std::string& str) { unsigned int bitsinunsignedint = (unsigned int) ( sizeof (unsigned int) * 8); unsigned int threequarters = (unsigned int) (( Bitsinunsignedint * 3)/4); unsigned int oneeighth = (unsigned int) (BITSINUNSIGNEDINT/8); unsigned int highbits & nbsp; = (unsigned int) (0xFFFFFFFF) << (bitsinunsignedint-oneeighth); unsigned int hash = 0; unsigned int Test = 0; for (std::size_t i = 0; i < str.length (); i++) { hash = (hash << oneeighth) + Str[i]; &nbsP;if (test = hash & highbits) != 0) { hash = ((hash ^ (test >> threequarters)) & (~highbits)); } } return Hash;}
4, Elfhashunsigned int elfhash (const std::string& str) {unsigned int hash = 0; unsigned int x = 0; for (std::size_t i = 0; i < str.length (); i++) {hash = (hash << 4) + str[i]; if ((x = hash & 0xf0000000l)! = 0) {hash ^= (x >> 24); } hash &= ~x; } return hash;}
5, Bkdrhashunsigned int bkdrhash (const std::string& str) {unsigned int seed = 131;//131 1313 13131 131313 etc.. unsigned int hash = 0; for (std::size_t i = 0; i < str.length (); i++) {hash = (hash * seed) + str[i]; } return hash;}
6, Sdbmhashunsigned int sdbmhash (const std::string& str) {unsigned int hash = 0; for (std::size_t i = 0; i < str.length (); i++) {hash = Str[i] + (hash << 6) + (hash << +)-hash; } return hash;}
7, Djbhash(TIMES33)-This is used very much and many libraries use it. unsigned int djbhash (const std::string& str) {unsigned int hash = 5381; for (std::size_t i = 0; i < str.length (); i++) {hash = ((hash << 5) + hash) + str[i]; } return hash;}
8, Dekhashunsigned int dekhash (const std::string& str) {unsigned int hash = static_cast (Str.length ()); for (std::size_t i = 0; i < str.length (); i++) {hash = ((hash << 5) ^ (hash >>)) ^ str[i]; } return hash;}
9, Bphashunsigned int bphash (const std::string& str) {unsigned int hash = 0; for (std::size_t i = 0; i < str.length (); i++) {hash = hash << 7 ^ str[i]; } return hash;}
10, Fnvhashunsigned int fnvhash (const std::string& str) {const unsigned int fnv_prime = 0X811C9DC5; unsigned int hash = 0; for (std::size_t i = 0; i < str.length (); i++) {hash *= fnv_prime; Hash ^= str[i]; } return hash;}
11, Aphashunsigned int aphash (const std::string& str) {unsigned int hash = 0xAAAAAAAA; for (std::size_t i = 0; i < str.length (); i++) {Hash ^= ((i & 1) = = 0)? ((hash << 7) ^ str[i] * (hash >> 3)): ((hash << one) + (Str[i] ^ (Has H >> 5))); } return hash;}
12, MurmurHash -A very new hashing algorithm, which should be the most efficient hashing algorithm at present, has a high usage rate. (pseudo code from Wikipedia) MURMUR2 (key, Len, Seed) m <-0x5bd1e995 r <-24 seed 0x9747b28c hash <-seed XOR len for Each fourbytechunk of key k <-fourbytechunk k <-k * m k <-k XOR (k >> R) & Nbsp; k <-k * m Hash <-hash * m hash <-hash XOR k With any remainingbytesinkey remainingbytes Swapendianorderof (Remainingbytesinkey) hash <-Hash XOR Remainingbytes &nbsP;hash <-Hash * M hash <-hash XOR (hash >>) hash < ;-Hash * M hash <-hash XOR (hash >>) murmurhash algorithm: High computational performance, low collision rate, Founded in 2008 by Austin Appleby, it has been applied to open source systems such as Hadoop, libstdc++, Nginx, and libmemcached. Appleby was hired by Google in 2011, then Google introduced its variant of the Cityhash algorithm.
Official website: https://sites.google.com/site/murmurhash/
MurmurHash algorithm, claiming to be super fast hash algorithm, is the FNV 4-5 times. The official figures are as follows:
oneatatime–354.163715 mb/sec
fnv–443.668038 mb/sec
superfasthash–985.335173 mb/sec
lookup3–988.080652 mb/sec
MurmurHash 1.0–1363.293480 mb/sec
MurmurHash 2.0–2056.885653 mb/sec
But there are also articles claiming that the MurmurHash is faster than DJB when the length of the key is greater than 10 bytes. "From a computational speed, the MurmurHash is only available for long-length characters of known length."
Commonly used hash algorithms
