class Matrices {

	public static void main(String[] args) {

		// a 2D array is an array of arrays
		// where each row is an array.

		char[] arr1 = {'x','o',' '};
		char[] arr2 = {'o','x','o'};
		char[] arr3 = {' ','o','x'};

		char[][] tic = {arr1,arr2,arr3};

		printMatrix(tic);

		// get element at row 1 column 2;
		char elm = tic[1][2];

		System.out.println("elm at row 1, col 2: " + elm);
	
		// set element at row 2 column 1 to 'z'

		tic[2][1] = 'z';

		printMatrix(tic);

		initArray('s', tic);

		printMatrix(tic);
	}

	public static void initArray(char c, char[][] m) {
		for(int i = 0; i < m.length; i++) {
			char[] arr = m[i];
			for(int j = 0; j < arr.length; j++) {
				arr[j] = c;
			}
		}
	}

	public static void printMatrix(char[][] m) {

		for(int row = 0; row < m.length; row++) {
			char[] arr = m[row];

			for(int i = 0; i < arr.length; i++) {
				System.out.print(arr[i] + " ");
			}	
			System.out.println();
		}
	}

}