What hashing algorithm outputs hash value as numbers only?

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    What hashing algorithm outputs hash value as numbers only?

    Hi, Gurus. What hashing algorithm outputs hash value as numbers only? For example, if you pass a “John Q. Public” it will output 23324. If there is no such hashing, how hard is it to hire somebody to write a fairly quick one? It could be some fast hashing and then another function that creates numbers. Much obliged. wkatz.

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    C++ Witch laserlight's Avatar
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    What hashing algorithm outputs hash value as numbers only?
    If you remove the restriction on "only", I think it would be all of them. Otherwise, it would be none of them, insofar as non-numeric data can be mapped to numbers and vice versa.

    If there is no such hashing, how hard is it to hire somebody to write a fairly quick one?
    Impossible, obviously. If it cannot be done, not even if you offer your soul as the price could it be done.
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    Thanks, Laserlight!

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    and the hat of wrongness Salem's Avatar
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    > What hashing algorithm outputs hash value as numbers only?
    All of them I would say.

    > if you pass a “John Q. Public” it will output 23324.
    A very basic one would be just add up the ASCII values of all the letters.
    Like 'J' + 'o' + 'h' + 'n' etc etc

    Code:
    int hash ( const char *string ) {
      int result = 0;
      while ( *string ) result += *string++;
      return result;
    }
    Now, where's my money?

    A good hash is another matter, one which doesn't produce obvious collisions for all anagrams for example.
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    Code Goddess Prelude's Avatar
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    >What hashing algorithm outputs hash value as numbers only?
    That's the definition of a hash function. It maps keys to integers that can be used as the index for a table. You probably want an algorithm that's tuned for strings, like shift-add-xor:
    Code:
    unsigned sax_hash ( void *key, int len )
    {
      unsigned char *p = key;
      unsigned h = 0;
      int i;
    
      for ( i = 0; i < len; i++ )
        h ^= ( h << 5 ) + ( h >> 2 ) + p[i];
    
      return h;
    }
    But any good algorithm will should work well. You seem to be mildly confused about hashing and hash tables, so browse this and this for some basic info.
    My best code is written with the delete key.

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    Algorithm Dissector iMalc's Avatar
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    Try pasing the characters of the string through a CRC algorithm.
    The CRC of the string gives a pretty good distribution.
    Just pick an appropriate sized CRC for the number of items to hash.

  7. #7
    pwns nooblars
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    Could do a basic hash that outputs to alphanumerics then convert each char to a number and use that.

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    EDIT: Mentioned by Wraithan.

    What kind of hash do you want? A checksum? Hash for a table? If you want a cryptographic hash, well, you're better off with a string. A teensy weensy integer is clearly not enough.
    Last edited by jafet; 09-11-2006 at 04:30 AM.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  9. #9
    Cat without Hat CornedBee's Avatar
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    All cryptographic hashes in use result in integers. They just happen to be very BIG integers. (SHA-256, as the name says, results in 256-bit-wide integers. That's a LOT.)
    All the buzzt!
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