Hashing function and bloom filter

   Refer to this model http://billmill.org/bloomfilter-tutorial/ 1) Using the 2 of the 9 hash functions you own, facsimile the regularity establish in the over model. 2) Next fashion a improve after a while unpremeditated inputs and use all 9 hashes this time http://pages.cs.wisc.edu/~cao/papers/summary-cache/node8.html 3) Choose divers spots in the consideration after a while 9 hashes and strengthen results after a while your program. False Positive -> (1-e^(-km/n))^k where n is the bit vector size k are the enumerate of hashes m are the enumerate of keys used in the hash to glut the vector. code c++ HashTest.cpp #include <iostream> //iostrem #include <string>   //string #include <vector>   //vector #include "GeneralHashFunctions.h" int ocean(int argc, char* argv[]) {    const std::string key = "abcdefghijklmnopqrstuvwxyz1234567890";    std::cout << "General Purpose Hash Function Algorithms Test" << std::endl;    std::cout << "By Arash Partow - 2002        " << std::endl;    std::cout << "Key: "                          << key           << std::endl;    std::cout << " 1. RS-Hash Function Value:   " << RSHash (key) << std::endl;    std::cout << " 2. JS-Hash Function Value:   " << JSHash (key) << std::endl;    std::cout << " 3. PJW-Hash Function Value: " << PJWHash (key) << std::endl;    std::cout << " 4. ELF-Hash Function Value: " << ELFHash (key) << std::endl;    std::cout << " 5. BKDR-Hash Function Value: " << BKDRHash(key) << std::endl;    std::cout << " 6. SDBM-Hash Function Value: " << SDBMHash(key) << std::endl;    std::cout << " 7. DJB-Hash Function Value: " << DJBHash (key) << std::endl;    std::cout << " 8. DEK-Hash Function Value: " << DEKHash (key) << std::endl;    std::cout << " 9. FNV-Hash Function Value: " << FNVHash (key) << std::endl;    std::cout << "10. BP-Hash Function Value:   " << BPHash (key) << std::endl;    std::cout << "11. AP-Hash Function Value:   " << APHash (key) << std::endl;    recur 1; } GeneralHashFunctions.cpp #include "GeneralHashFunctions.h" unsigned 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;    }    recur hash; } /* End Of RS Hash Function */ unsigned 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));    }    recur hash; } /* End Of JS Hash Function */ unsigned 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          = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);    unsigned int hash              = 0;    unsigned int experience              = 0;    for(std::size_t i = 0; i < str.length(); i++)    {       hash = (hash << OneEighth) + str[i];       if((experience = hash & HighBits) != 0)       {          hash = (( hash ^ (experience >> ThreeQuarters)) & (~HighBits));       }    }    recur hash; } /* End Of P. J. Weinberger Hash Function */ unsigned 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;    }    recur hash; } /* End Of ELF Hash Function */ unsigned int BKDRHash(const std::string& str) {    unsigned int root = 131; // 31 131 1313 13131 131313 etc..    unsigned int hash = 0;    for(std::size_t i = 0; i < str.length(); i++)    {       hash = (hash * root) + str[i];    }    recur hash; } /* End Of BKDR Hash Function */ unsigned 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 << 16) - hash;    }    recur hash; } /* End Of SDBM Hash Function */ 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];    }    recur hash; } /* End Of DJB Hash Function */ unsigned 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 >> 27)) ^ str[i];    }    recur hash; } /* End Of DEK Hash Function */ unsigned 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];    }    recur hash; } /* End Of BP Hash Function */ unsigned 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];    }    recur hash; } /* End Of FNV Hash Function */ unsigned 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 << 11) + (str[i] ^ (hash >> 5))));    }    recur hash; } /* End Of AP Hash Function */ GeneralHashFunctions.h #ifndef INCLUDE_GENERALHASHFUNCTION_CPP_H #define INCLUDE_GENERALHASHFUNCTION_CPP_H #include typedef unsigned int (*HashFunction)(const std::string&); unsigned int RSHash (const std::string& str); unsigned int JSHash (const std::string& str); unsigned int PJWHash (const std::string& str); unsigned int ELFHash (const std::string& str); unsigned int BKDRHash(const std::string& str); unsigned int SDBMHash(const std::string& str); unsigned int DJBHash (const std::string& str); unsigned int DEKHash (const std::string& str); unsigned int BPHash (const std::string& str); unsigned int FNVHash (const std::string& str); unsigned int APHash (const std::string& str); #endif