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

Take a look at the source code of java.lang.String.

/**
 * Returns a hash code for this string. The hash code for a
 * String object is computed as
 * 
 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
 * 
 * using int arithmetic, where s[i] is the
 * ith character of the string, n is the length of
 * the string, and ^ indicates exponentiation.
 * (The hash value of the empty string is zero.)
 *
 * @return  a hash code value for this object.
 */
public int hashCode() {
    int h = hash;
    int len = count;
    if (h == 0 && len > 0) {
        int off = offset;
        char val[] = value;
        for (int i = 0; i < len; i++) {
            h = 31*h + val[off++];
        }
        hash = h;
    }
    return h;
}