OpenEuphoria

Routines

hash

<built-in> function hash(object source, atom algo) 

calculates a hash value for a key using the algorithm algo.

Parameters:

1. source : Any Euphoria object
2. algo : A code indicating which algorithm to use.
   • HSIEH30 uses Hsieh. Returns a 30-bit (a Euphoria integer). Fast and good dispersion
   • HSIEH32 uses Hsieh. Returns a 32-bit value. Fast and very good dispersion
   • ADLER32 uses Adler. Very fast and reasonable dispersion, especially for small strings
   • FLETCHER32 uses Fletcher. Very fast and good dispersion
   • MD5 uses MD5 (not implemented yet) Slower but very good dispersion. Suitable for signatures.
   • SHA256 uses SHA256 (not implemented yet) Slow but excellent dispersion. Suitable for signatures. More secure than MD5.
   • 0 and above (integers and decimals) and non-integers less than zero use the cyclic variant (hash = hash * algo + c). This is a fast and good to excellent dispersion depending on the value of algo. Decimals give better dispersion but are slightly slower.

Returns:

An atom, Except for the HSIEH30, MD5 and SHA256 algorithms, this is a 32-bit integer.
An integer, Except for the HSIEH30 algorithms, this is a 30-bit integer.
A sequence, MD5 returns a 4-element sequence of integers
SHA256 returns a 8-element sequence of integers.

Comments:

• For algo values from zero to less than one, that actual value used is (algo + 69096).

Example 1:

? hash("The quick brown fox jumps over the lazy dog", 0         ) --> 3071488335 
? hash("The quick brown fox jumps over the lazy dog", 99        ) --> 4122557553 
? hash("The quick brown fox jumps over the lazy dog", 99.94     ) -->   95918096 
? hash("The quick brown fox jumps over the lazy dog", -99.94    ) --> 4175585990 
? hash("The quick brown fox jumps over the lazy dog", HSIEH30   ) -->   96435427 
? hash("The quick brown fox jumps over the lazy dog", HSIEH32   ) -->   96435427 
? hash("The quick brown fox jumps over the lazy dog", ADLER32   ) --> 1541148634 
? hash("The quick brown fox jumps over the lazy dog", FLETCHER32) --> 1730140417 
? hash(123,                                           99        ) --> 1188623852 
? hash(1.23,                                          99        ) --> 3808916725 
? hash({1, {2,3, {4,5,6}, 7}, 8.9},                   99        ) -->  526266621