Connect Four game in Scala - arrays

Question

I'm trying to make a connect four game in scala. Currently i have the board print out and ask player 1 for a move, once player 1 choses a number a board prints out with an X in the column where player 1 chose. then player 2 picks a number. My problem is that once i pick a number that player's letter fills the whole column and you ant build on top of that.
heres an example of what happens
. X . O X . . .
. X . O X . . .
. X . O X . . .
. X . O X . . .
. X . O X . . .
. X . O X . . .
. X . O X . . .
. X . O X . . .
0 1 2 3 4 5 6 7
// Initialize the grid
val table = Array.fill(9,8)('.')
var i = 0;
while(i < 8){
table(8)(i) = (i+'0').toChar
i = i+1;
}
/* printGrid: Print out the grid provided */
def printGrid(table: Array[Array[Char]]) {
table.foreach( x => println(x.mkString(" ")))
}
/*//place of pieces X
def placeMarker(){
val move = readInt
//var currentRow = 7
while (currentRow >= 0)
if (table(currentRow)(move) != ('.')){
currentRow = (currentRow-1)
table(currentRow)(move) = ('X')
return (player2)}
else{
table(currentRow)(move) = ('X')
return (player2)
}
}
//place of pieces O
def placeMarker2(){
val move = readInt
//var currentRow = 7
while (currentRow >= 0)
if (table(currentRow)(move) != ('.')){
currentRow = (currentRow-1)
table(currentRow)(move) = ('O')
return (player1)}
else{
table(currentRow)(move) = ('O')
return (player1)
}
}
*/
def placeMarker1(){
val move = readInt
var currentRow = 7
while (currentRow >= 0)
if (table(currentRow)(move) !=('.'))
{currentRow = (currentRow-1)}
else{table(currentRow)(move) = ('X')}
}
def placeMarker2(){
val move = readInt
var currentRow = 7
while (currentRow >= 0)
if (table(currentRow)(move) !=('.'))
{currentRow = (currentRow-1)}
else{table(currentRow)(move) = ('O')}
}
//player 1
def player1(){
printGrid(table)
println("Player 1 it is your turn. Choose a column 0-7")
placeMarker1()
}
//player 2
def player2(){
printGrid(table)
println("Player 2 it is your turn. Choose a column 0-7")
placeMarker2()
}
for (turn <- 1 to 32){
player1
player2
}

Answer 1

Your global state is messing you up: var currentRow = 7
Instead of trying to keep track of a global "currentRow" across all columns, I'd recommend one of two things:
Keep a separate "currentRow" for each column in a currentRows array.
Just iterate through the column each time you place a piece to find the lowest empty slot.
Actually, it looks like you were originally doing the second suggestion, but you commented out your local currentRow variables and declared a global (instance-level) one instead.