记录几个经典的字符串hash算法

记录几个经典的字符串hash算法，方便以后查看：

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http://www.partow.net/programming/hashfunctions/#

（1）暴雪字符串hash

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdbool.h>

 #define MAXTABLELEN 102400000

 typedef struct  _HASHTABLE
 {
     long nHashA;
     long nHashB;
     bool bExists;
 }HASHTABLE, *PHASHTABLE;

 const unsigned long nTableLength = MAXTABLELEN;
 unsigned long m_tablelength;    // 哈希索引表长度
 HASHTABLE *m_HashIndexTable;
 unsigned long cryptTable[0x500];

 int collc = ;
 int errstr = ;

 void InitCryptTable()
 {
     unsigned long seed = 0x00100001, index1 = , index2 = , i;  

     for( index1 = ; index1 < 0x100; index1++ )
     {
         for( index2 = index1, i = ; i < ; i++, index2 += 0x100 )
         {
             unsigned long temp1, temp2;
             seed = (seed *  + ) % 0x2AAAAB;
             temp1 = (seed & 0xFFFF) << 0x10;
             seed = (seed *  + ) % 0x2AAAAB;
             temp2 = (seed & 0xFFFF);
             cryptTable[index2] = ( temp1 | temp2 );
         }
     }
 }  

 /************************************************************************/
 /*函数名：HashString
  *功  能：求取哈希值
  *返回值：返回hash值
  ************************************************************************/
 unsigned long HashString(char *lpszString, unsigned long dwHashType)
 {
     unsigned char *key = (unsigned char *)lpszString;
     unsigned long seed1 = 0x7FED7FED, seed2 = 0xEEEEEEEE;
     int ch; 

     while(*key != )
     {
         ch = toupper(*key++);

         seed1 = cryptTable[(dwHashType << ) + ch] ^ (seed1 + seed2);
         seed2 = ch + seed1 + seed2 + (seed2 << ) + ;
     }
     return seed1;
 }
 /************************************************************************/
 /*函数名：Hashed
  *功  能：检测一个字符串是否被hash过
  *返回值：如果存在，返回位置；否则，返回-1
  ************************************************************************/
 unsigned long Hashed(char * lpszString)  

 {
     const unsigned long HASH_OFFSET = , HASH_A = , HASH_B = ;
     //不同的字符串三次hash还会碰撞的率无限接近于不可能
     unsigned long nHash = HashString(lpszString, HASH_OFFSET);
     unsigned long nHashA = HashString(lpszString, HASH_A);
     unsigned long nHashB = HashString(lpszString, HASH_B);
     unsigned long nHashStart = nHash % m_tablelength;
     unsigned long nHashPos = nHashStart;  

     while (m_HashIndexTable[nHashPos].bExists)
     {
         if (m_HashIndexTable[nHashPos].nHashA == nHashA && m_HashIndexTable[nHashPos].nHashB == nHashB)
             return nHashPos;
         else
             nHashPos = (nHashPos + ) % m_tablelength;  

         if (nHashPos == nHashStart)
             break;
     }
     errstr++;

     return -; //没有找到
 }  

 /************************************************************************/
 /*函数名：Hash
  *功  能：hash一个字符串
  *返回值：成功，返回true；失败，返回false
  ************************************************************************/
 bool Hash(char * lpszString)
 {
     const unsigned long HASH_OFFSET = , HASH_A = , HASH_B = ;
     unsigned long nHash = HashString(lpszString, HASH_OFFSET);
     unsigned long nHashA = HashString(lpszString, HASH_A);
     unsigned long nHashB = HashString(lpszString, HASH_B);
     unsigned long nHashStart = nHash % m_tablelength,
     nHashPos = nHashStart;  

     while (m_HashIndexTable[nHashPos].bExists)
     {
         nHashPos = (nHashPos + ) % m_tablelength;
         if (nHashPos == nHashStart) //一个轮回
         {
             collc ++;
             //hash表中没有空余的位置了,无法完成hash
             return false;
         }
     }
     m_HashIndexTable[nHashPos].bExists = true;
     m_HashIndexTable[nHashPos].nHashA = nHashA;
     m_HashIndexTable[nHashPos].nHashB = nHashB;  

     return true;
 }

 int InitHashTable()
 {
     int i;

     InitCryptTable();
     m_tablelength = nTableLength;

     m_HashIndexTable = (HASHTABLE *)malloc(nTableLength * sizeof(HASHTABLE));
     if (NULL == m_HashIndexTable) {
         printf("Init HashTable failure!!\n");
         return -;
     }

     for (i = ; i < nTableLength; i++ )
     {
         m_HashIndexTable[i].nHashA = ;
         m_HashIndexTable[i].nHashB = ;
         m_HashIndexTable[i].bExists = false;
     }

     return ;
 }

 void do_test()
 {
     int count = ;
     FILE *fp;
     char url[] = {};

     fp = fopen("urllist", "rb+");
     if (NULL == fp) {
         return;
     }

     if (InitHashTable()) {
         return;
     }

     while (!feof(fp)) {
         fgets(url, , fp);
         Hash(url);
         count++;
     }

     printf("count: %d\n", count);

     fclose(fp);
 }

 /*test main*/
 int main()
 {
     do_test();

     printf("conflict: %d\n", collc);
     printf("not find: %d\n", errstr);

     return ;
 }

（2）字符串hash算法 ELFhash

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define MOD 10

int ELFhash(char*key)
{
    unsigned long h=;
    while(*key)
    {
        h = (h << ) + *key++;
        unsigned long g = h & 0xF0000000L;
        if(g)
            h ^= g >> ;
        h &= ~g;
    }
    return h % MOD;
}

int main(int argc, char **argv)
{
    if (argc < ) {
        printf("using %s <string>\n", argv[]);
        return -;
    }   

    int num = ;
    num = ELFhash(argv[]);

    printf("num is %d\n", num);
}