字符串hash-BKDRHash

 unsigned int BKDRHash(char *str)
 {
     unsigned int seed = ; // 31 131 1313 13131 131313 etc..
     unsigned int hash = ;

     while (*str)
     {
         hash = hash * seed + (*str++);
     }

     return (hash & 0x7FFFFFFF);
 }