Tic Tac Toe in Ruby

I suggest to divide the dropPiece function in smaller, easy and readable parts as follows:

 def is_empty(row,col) @board[row][col] === " " end def inside_board(row,col) (0..2) === row and (0..2) === col end def valid_move(row,col) is_empty(row,col) and inside_board(row,col) end def dropPiece(piece, row, col) #makeMove @board[row][col] = piece if valid_move(row,col) end 

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The following piece of code should be

1. Commented or
2. A function with a meaningful name:

:

@board.join.split('').include?(" ") 

I would have used:

def isTie @board.join.split('').include?(" ") end return "C" if isTie 

Do not be scared of writing small one-liner functions, they will increibly lower debugging time by improving modularity and readibility.

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You use the so much puts "\n" * 100 define a function and use that:

def clearScreen puts "\n" * 100 end 

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In findWinner you should return false if you have not decided, this allows you to change the code from

while board.findWinner == "U" 

to

while not board.findWinner 

that is much clearer.

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The following should be a function called something like alert_winner(winner)

puts "\n" * 100 puts " --**~^^^^^^^~**--" if winner == "C" puts " C A T S G A M E" else puts " #{winner} ' S W I N" end puts " ----**~vVv~**----" puts "\n" board.printBoard puts "\n **~V~**" 

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The following should be a function called promptUser

 puts " #{active_player}'s turn. Choose a box!", " **~V~**" print " " move = gets.chomp.to_i - 1 row = move / 3 col = move % 3 

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In my opinion the main part should be the shorter possible and only call other functions

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Minor: you should use and instead of &&, they are exactly the same but the first one is clearer.

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Putting it all together, here's the improved version(I added a tiny method at the end):

class Board def initialize @board = Array.new(3) { Array.new(3, " ") } end def printInstructions puts "1 | 2 | 3", "---------", "4 | 5 | 6", "---------", "7 | 8 | 9" print "\n" end def printBoard (0..2).each do |row| print " " (0..2).each do |col| print @board[row][col] print " | " unless col == 2 end print "\n" print " ---------\n" unless row == 2 end print "\n" end def isTie @board.join.split('').include?(" ") end def findWinner # X X X X # & X # X (0..2).each do |i| if @board[i][0] == @board[i][1] && @board[i][1] == @board[i][2] return @board[i][0] unless @board[i][0] == " " elsif @board[0][i] == @board[1][i] && @board[1][i] == @board[2][i] return @board[0][i] unless @board[0][i] == " " end end # X X # X & X # X X if ( @board[0][0] == @board[1][1] && @board[1][1] == @board[2][2] ) || ( @board[0][2] == @board[1][1] && @board[1][1] == @board[2][0] ) return @board[1][1] unless @board[1][1] == " " end # X O X # X O X # O X O return "C" unless isTie return false end def is_empty(row,col) @board[row][col] === " " end def inside_board(row,col) (0..2) === row and (0..2) === col end def valid_move(row,col) is_empty(row,col) and inside_board(row,col) end def dropPiece(piece, row, col) @board[row][col] = piece if valid_move(row,col) end end def clear_screen puts "\n" * 100 end def prompt_move(active_player) puts " #{active_player}'s turn. Choose a box!", " **~V~**" print " " move = gets.chomp.to_i - 1 row = move / 3 col = move % 3 return row,col end def alert_winner(winner,board) puts " --**~^^^^^^^~**--" if winner == "C" puts " C A T S G A M E" else puts " #{winner} ' S W I N" end puts " ----**~vVv~**----" puts "\n" board.printBoard puts "\n **~V~**" end def ticTacToe(boardClass) board = boardClass.new active_player = "X" clear_screen board.printInstructions while not board.findWinner row,col = prompt_move(active_player) clear_screen if board.dropPiece(active_player, row, col) if active_player == "X" active_player = "O" else active_player = "X" end else puts " Invalid move, please select again\n\n" end board.printBoard end winner = board.findWinner clear_screen alert_winner(winner,board) end while true clear_screen puts "Do you want to play again? (y/n)" if ["no","n"].include? (gets.chomp.downcase) puts "Goodbye" break end ticTacToe(Board) end