Tic Tac Toe Matrix Check

Hello everyone. I'm VERY new to MatLab and the world of coding and I'm confused as to how I move forward from where I am at the moment. My problem is this: I've got a Tic-Tac-Toe game where the computer starts by randomly selecting a spot in a 3x3 matrix. I then make my turn, and the computer goes again and so forth. However, The computer will at times pick a spot that is already taken, and I'm wondering how I can write a statement that will tell the computer to check the matrix for spot's that are available and not taken?

my code for CPU making a move:

CPUMove = randsample(11:19,1);
switch (CPUMove)
    case 11
        Board (1,1) = 0;
    case 12
        Board (1,2) = 0;
    case 13
        Board (1,3) = 0;
    case 14
        Board (2,1) = 0;
    case 15
        Board (2,2) = 0;
    case 16
        Board (2,3) = 0;
    case 17
        Board (3,1) = 0;
    case 18
        Board (3,2) = 0;
    case 19
        Board (3,3) = 0;
end

Code for Player to make a move:

X = input (' Human Player, make your move. Pick a spot on the board 1-9: ');
 switch (X)
    case 1
        Board(1,1) = 1;
    case 2
        Board (1,2) = 1;
    case 3
        Board (1,3) = 1;
    case 4
        Board (2,1) = 1;
    case 5
        Board (2,2) = 1;
    case 6
        Board (2,3) = 1;
    case 7 
        Board (3,1) = 1;
    case 8
        Board (3,2) = 1;
    case 9
        Board (3,3) = 1;
 end
 if Board (1,1) == 0
     Board (1,1) ~= 1;
 elseif Board (1,2) == 0
     Board (1,2) ~= 1;
 elseif Board (1,3) == 0
     Board (1,3) ~= 1;
 elseif Board (2,1) == 0
     Board (2,1) ~= 1;
 elseif Board (2,2) == 0
     Board (2,2) ~= 1;
 elseif Board (2,3) == 0
     Board (2,3) ~= 1;
 elseif Board (3,1) == 0
     Board (3,1) ~= 1;
 elseif Board (3,2) == 0
     Board (3,2) ~= 1;
 elseif Board (3,3) == 0
     Board (3,1) ~= 1;
 end

Answer 1

[Jan]

Note that

Board (1,1) ~= 1;

Compares the contents of this elements to be different from 1, but nothing is assigned. Therefore this line, and the complete block of code, is useless.

A simplification of the first part:

CPUMove = randsample(11:19,1);
switch (CPUMove)
  case 11
      Board (1,1) = 0;
...

is:

CPUMove = randsample(11:19,1);
Board(CPUMove - 10) = 0;

But then the fields on the board are ordered columnwise, such that CPUMove=12 means Board(2,1).

This can be applied to the other part also.

[Stuart Nezlek]

So are you saying that I need to assign something to a value different than 1? Because I'm trying to write out that the CPU move on the board would be = 0 and my move as the human would be = 1.

[Jan]

Board = NaN(3,3);
disp(Board);
CPUMove = 4;
Board(CPUMove) = 0;
disp(Board);
YouMove = 5;
Board(YouMove) = 1;
disp(Board);

Clear? You can use "linear indexing" to avoid the bunch of switch branches.