适用的字符串hash函数

下面是综合情况比较好的两个字符串hash函数，就当做一个笔记吧：

unsigned int BKDRHash(char *str){unsigned int seed = 131; // 31 131 1313 13131 131313 etc...unsigned int hash = 0;while (*str){hash = hash * seed + (*str++);}return (hash & 0x7FFFFFFF);}unsigned int JSHash(char *str){unsigned int hash = 1315423911; // nearly a prime - 1315423911 = 3 * 438474637if (*str == 0x00){return 0;}while (*str){hash ^= ((hash << 5) + (*str++) + (hash >> 2));}return (hash & 0x7FFFFFFF);}

整型hash函数：

static int _GetIndex(unsigned int addr)
{
 return (addr * 2654435769UL) >> 24;
}

static int indexFor(int hash, int length)
{
 return hash & (length - 1); //一般长度应为2的幂次方
}