How to calculate the hash code of a string by hand?

Question

I was wondering how to calculate the hash code for a given string by hand. I understand that in Java, you can do something like:

String me = \"What you say what          


        

Answer 1

Most hash functions of this sort calculate the hash value modulo some large number (e.g. a large prime). This avoids overflows and keeps the range of values returned by the function within a specified range. But this also means an infinite range of input values will get a hash value from a finite set of possible values (i.e. [0,modulus)), hence the problem of hash collisions.

In this case, the code would look something like this:

   public int hash(String x){
        int hashcode=0;
        int MOD=10007;
        int shift=29;
        for(int i=0;i

Exercise for the reader:

See the code for the hashCode function for java.util.String. Can you see why it does not use a modulus explicitly?