Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
944 views
in Technique[技术] by (71.8m points)

algorithm - What is the best 32bit hash function for short strings (tag names)?

What is the best 32bit hash function for relatively short strings?

Strings are tag names that consist of English letters, numbers, spaces and some additional characters (#, $, ., ...). For example: Unit testing, C# 2.0.

I am looking for 'best' as in 'minimal collisions', performance is not important for my goals.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

I'm not sure if it's the best choice, but here is a hash function for strings:

The Practice of Programming (HASH TABLES, pg. 57)

/* hash: compute hash value of string */
unsigned int hash(char *str)
{
   unsigned int h;
   unsigned char *p;

   h = 0;
   for (p = (unsigned char*)str; *p != ''; p++)
      h = MULTIPLIER * h + *p;
   return h; // or, h % ARRAY_SIZE;
}

Empirically, the values 31 and 37 have proven to be good choices for the multiplier in a hash function for ASCII strings.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...