// APS101, Winter 2009: Lecture 27 (Mar. 17)
//
// Review: last time we began looking at 2-Dimensional Arrays.

// 1-D array: int[]
// 2-D array: int[][]

// it's useful to think of a 2-D array as a 1-D array that stores
// other 1-D arrays - the principles are the same. 
// (e.g., you still access the contents of an array using indices.)

int[][] a = new int[3][];
a.length
a[0] // why is it null?
a[0] = new int[10];
a
a[0].length;
a[1] = new int[5];

// exercise: make a 2-D array that stores the following:
// 1 2 3
// 4 5 6

int[][] a = new int[2][3];

for (int i = 0; i <= 1; i++) { // for each of the 2 rows
      for (int j = 0; j <= 2; j++) { // for each of the 3 columns
          a[i][j] = j + 1 + 3 * i;
      }
}

// now, if we want to print the contents of an array:

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

// for the next few lectures, we will write a Tic-Tac-Toe game,
// in order to practice everything we've learned.
// (this will help you with Assignment 3!)
// the game will be both in text mode, and with a GUI.

// first, we will need to develop the game "engine", which is the 
// class that contains the "behind the scenes" methods that do all the work.

// think about how to represent the tic-tac-toe game...
// we need a square grid to put an 'X' or an 'O' on it.
// char[][] a: a is an array of char arrays

// (take a look at TicTacToe.java)

TicTacToe t = new TicTacToe();
t
t.board // for now, we have no other way of seeing the game

// now, we want to be able to put an 'X' or an 'O'
t.setMark('X', 0, 0);
t.board
t.setMark('O', 1, 1);
t.board
t.setMark('X', 1, 1); // doesn't change anything!
t.board

// now, we need to visualize the game... for example:

// empty grid:
 | |
- - -
 | |
- - -
 | |

// or:
X| |
- - -
O|O|
- - -
 | |

// we need to write a toString() method for this.