C# Array Subset fetching

Question

I have an array of bytes and i want to determine if the contents of this array of bytes exists within another larger array as a continuous sequence. What is the simplest way to

Answer 1

This, which is a 1/1 port of this answer: Searching for a sequence of Bytes in a Binary File with Java

Is a very efficient way of doing so:

public static class KmpSearch {

    public static int IndexOf(byte[] data, byte[] pattern) {
        int[] failure = ComputeFailure(pattern);

        int j = 0;
        if (data.Length == 0) return -1;

        for (int i = 0; i < data.Length; i++) {
            while (j > 0 && pattern[j] != data[i]) {
                j = failure[j - 1];
            }
            if (pattern[j] == data[i]) { j++; }
            if (j == pattern.Length) {
                return i - pattern.Length + 1;
            }
        }
        return -1;
    }


    private static int[] ComputeFailure(byte[] pattern) {
        int[] failure = new int[pattern.Length];

        int j = 0;
        for (int i = 1; i < pattern.Length; i++) {
            while (j > 0 && pattern[j] != pattern[i]) {
                j = failure[j - 1];
            }
            if (pattern[j] == pattern[i]) {
                j++;
            }
            failure[i] = j;
        }

        return failure;
    }
}