Question

i am working on a small java program, its very basic and one of my functions shifts the alphabet by a given key. i have got it working, but its shifting the wrong way, how can i make it shift the other direction?

public static char[] ourAlphabet = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};


    public  char[] shiftAlphabet(int key) {

            int length = ourAlphabet.length;

            char[] result = new char[length];

            for (int i=0; i < length; i++)
            {
                result[(i+key+26)%length] = ourAlphabet[i];
            }

            return result;
    }

Im guessing its very simple, but its confused me!

For example;
with a key 19 produces;
hijklmnopqrstuvwxyzabcdefg

when is should produce;
TUVWXYZABCDEFGHIJKLMNOPQRS

Answer 1

It should work if you use result[(i-key+26)%length] = ourAlphabet[i];

However, if length != 26 this would still give a wrong result.

I would therefore replace the 26 by length;

result[(i-key+length)%length] = ourAlphabet[i];