Question

For my end of year project I need to develop an image processing and artificial intelligence application.

My image processing is already done, so I’m moving to the AI. However I have a problem here.

I will try to describe the situation here.

For a correct image processing I need an AI that can validate the board through the rules of checkers. So I need to check the current state of the play field with the last known state.

So for this I created an object with the currentBoard 2 dimensional array, and a method that validates the raw input of the board with the currentBoard (= last known state).

However, when another object — my image processing object — is finished with his method, it will change the array currentBoard in my AI object.

This is the same for a new array I created inside the main form. I think this happens cause of the heap/stack.

I hope I made my problem clear and understandable. I know I’m not the best in describing situations so please tell me when you don’t understand a part completely.

Answer 1

Arrays are reference types, so, as you’ve found, changing the array contents in one place will change it for any other code which holds a reference to the same object.

To avoid changing the array, you should take a deep copy of your 2 dimensional array and work with the copy instead. Note that we have to take a deep copy of both the array and its internal arrays:

        int[][] original = {new[] {1,2,3}, new[] {4,5,6}};

        int[][] deepCopy = new int[original.Length][];

        for (int index = 0; index < original.Length; index++)
        {
            var row = original[index];
            int[] rowCopy = new int[row.Length];
            row.CopyTo(rowCopy, 0);

            deepCopy[index] = rowCopy;
        }

You can also produce the same result using some simple linq:

int[][] deepCopyLinq = original.Select(x => x.ToArray()).ToArray();