hash - Why are 5381 and 33 so important in the djb2 algorithm? -

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is a hash function for the string 

  unsigned long hash = 5381; Int c; While (c = * str ++) hash = ((hash> <5) + hash) + c; Why 5381 and 33 are so important?   
 
    "text"> 
 this hash function is a ( LCG - is the simple category of function that generates a series of psuedo-random numbers), which is usually the form:  
  X = (one * x) + c; // "Mod M", where M = 2 ^ 32 or 2 ^ 64 usually  
 
 Note the similarity of the DBB2 hash function ... a = 33, M = 2 ^ 32 For a LCG, there should be special properties in "full duration" (i.e. that may be random),  one : 
 
     
  •  A-1 divisor All the major factors in M's (A1's 32, which is divisible by 2, is the only main factor of 2 ^ 32) 
    •  
  •  4 is a lot bigger if a multi-m4 (yes and Yes) 
    •  
 
 In addition,  C  and < Em> M  is considered to be relatively prominent (which would be right for the strange value  c ) 
 
 So as you can see, this hash function resembles some good LCG and when it comes to hash functions, you want to have a "random" distribution of a hash value that is real A real set of string is given to. 
 
 This is the reason why this hash function is good for strings, I think it is a good balance to be fast, giving proper distribution of hash values ​​but I have seen many other hash functions Claims better output characteristics, but include many more lines of code, see for example 
 
 Edit: Tells why 33 and 5381 are for practical reasons. Who were.

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