To Your Battle Stations! - Bit of a curiosity


Hey I got everything working accordingly and made it through all the lessons, but there's one thing I found that still doesn't work. When being prompted to enter either a column or a row, if I press enter before entering a value the game immediately crashes and presents this error:
Traceback (most recent call last):
File "python", line 28, in
ValueError: invalid literal for int() with base 10: ''
I wanted to know how to set up the code so that this doesn't happen if someone accidentally presses enter before typing in a value

from random import randint

board = []

for x in range(5):
    board.append(["O"] * 5)

def print_board(board):
    for row in board:
        print " ".join(row)

print "Let's play Battleship!"

def random_row(board):
    return randint(0, len(board) - 1)

def random_col(board):
    return randint(0, len(board[0]) - 1)

ship_row = random_row(board)
ship_col = random_col(board)

# Everything from here on should go in your for loop!
# Be sure to indent four spaces!
for turn in range(4):
    guess_row = int(raw_input("Guess Row:"))
    guess_col = int(raw_input("Guess Col:"))

    if guess_row == ship_row and guess_col == ship_col:
        print "Congratulations! You sunk my battleship!"
        if (guess_row < 0 or guess_row > 4) or (guess_col < 0 or guess_col > 4):
            print "Oops, that's not even in the ocean."
        elif(board[guess_row][guess_col] == "X"):
            print "You guessed that one already."
            print "You missed my battleship!"
            board[guess_row][guess_col] = "X"
        if turn == 3:
            print "Game Over"
    # Print (turn + 1) here!
    print "turn", turn + 1



With a google search
python how to check on raw input value
found for instance


did you check other topics? Someone recently asked this question:

dave and i both gave valid ways to handle this


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