DJB Hash 俗称 Times33 算法。
作用：将字符串映射成一个整数
用法：顾名思义，每次用HASH 值乘 33,加上字符ASCII值
hash(i) = hash(i-1) * 33 + str[i]
下面是优化的代码：
unsigned int DJBHash(const char* str, unsigned int length) { unsigned int hash = 5381; //0也没问题 unsigned int i = 0; for (i = 0; i < length; ++str, ++i) { hash = ((hash << 5) + hash) + (*str); //等价hash(i-1) * 33 + str[i]。5(2) = 32(10) } return hash; }/*Why hash is 5381?1. odd number
2. prime number
3. deficient number
4. 001/010/100/000/101 b
*/
参考文献:
http://www.partow.net/programming/hashfunctions/#top
http://guyot.blog.163.com/blog/static/120574021201011374439716/
https://stackoverflow.com/questions/10696223/reason-for-5381-number-in-djb-hash-function/13809282
https://stackoverflow.com/questions/1579721/why-are-5381-and-33-so-important-in-the-djb2-algorithm
https://www.cnblogs.com/napoleon_liu/articles/1911571.html
转载于:https://www.cnblogs.com/--zz/p/11141385.html
