Simple game of Tic-Tac-Toe created in Lua. View comments for more details

TicTacToe.lua

--Start a new game
function new()
	a = {" "," "," "}
	b = {" "," "," "}
	c = {" "," "," "}
	player = 1
	print("New game started")
end

--Print board to screen
function board()
	print("\n")
	print("     A   B   C ")
	print("\n")
	print(" 1   "..a[1].." | "..b[1].." | "..c[1].." ")
	print("    ------------")
	print(" 2   "..a[2].." | "..b[2].." | "..c[2].." ")
	print("    ------------")
	print(" 3   "..a[3].." | "..b[3].." | "..c[3].." ")
	print("\n")
end

--Check to see if there is a winner
function win(id)
	if isblank(a) and isblank(b) and isblank(c) then return false end

	if linecheck(a[1],b[1],c[1]) and a[1] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(a[2],b[2],c[2]) and a[2] ~= " "then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(a[3],b[3],c[3]) and a[3] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(a[1],a[2],a[3]) and a[1] ~= " "then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(b[1],b[2],b[3]) and b[1] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(c[1],c[2],c[3]) and c[1] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(a[1],b[2],c[3]) and a[1] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif linecheck(c[1],b[2],a[3]) and c[1] ~= " " then
		print("Player #"..id.." has won!!");
		return true
	elseif fullboard() then
		print("No player has won. Please try again");
		return true
	else
		return false
	end
end

--Ensure that the columns are blank
function isblank(col)
	local count = 0
	for _,v in pairs(col) do
		if v == " " then
			count = count + 1
		end
	end
	if count == 3 then return true end
	return false
end

--Check to see if there is no decisive winner
function fullboard()
	local count = 0
	for i = 1,3 do
		if (a[i] ~= " ") and (b[i] ~= " ") and (c[i] ~= " ") then
			count = count + 1
		end
	end
	if count == 3 then return true end
	return false
end

--Check to determine if the player has 3 in a row
function linecheck(i,j,k)
	return (i == j) and (i == k) and (j == k)
end

--Place a particular players marker in a cell
function boardplacement(cell)
	local pm = string.lower(cell)
	local mark

	if player == 1 then
		mark = "X"
	else
		mark = "O"
	end

	if pm == "a1" and a[1] == " " then
		a[1] = mark
		return true
	elseif pm == "a2" and a[2] == " " then
		a[2] = mark
		return true
	elseif pm == "a3" and a[3] == " " then
		a[3] = mark
		return true
	elseif pm == "b1" and b[1] == " " then
		b[1] = mark
		return true
	elseif pm == "b2" and b[2] == " " then
		b[2] = mark
		return true
	elseif pm == "b3" and b[3] == " " then
		b[3] = mark
		return true
	elseif pm == "c1" and c[1] == " " then
		c[1] = mark
		return true
	elseif pm == "c2" and c[2] == " " then
		c[2] = mark
		return true
	elseif pm == "c3" and c[3] == " " then
		c[3] = mark
		return true
	else
		print("Unknown cell or Cell is already occupied")
		return false
	end
end

--Move player pointer to the next player
function nextPlayer()
	if player == 1 then
		player = 2
	else
		player = 1
	end
end

--Start game function
function start(cmd)
	if cmd == "n" then
		new()
		local currentplayer
		repeat
			currentplayer = player
			io.write("Player #"..currentplayer..", enter cell number:")
			io.flush()
			if boardplacement(io.read()) then
				nextPlayer()
			end
			board()
		until (win(currentplayer) == true)
	else
		print ("Unknown Command")
	end
end

--Infinite loop to start program. 'q' to break the loop and quit
while true do
	io.write("Press 'n' to start a new game and 'q' to quit):")
	io.flush()
	local answer = io.read()
	if answer == "q" then
		break
	else
		start(answer)
	end
end