prac-4-beginners/solutions/ch-11-error-handling/readme.html

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    <h2 id="solution-for-error-handling-in-tic-tac-toe">
      Solution for error handling in tic-tac-toe
    </h2>
    <p>
      The only part of this first pass on the game that could fail is choosing
      the location.
    </p>
    <p>
      Did you notice that when it asks for a number, if you don’t enter anything
      it crashes hard?
    </p>
    <p>
      How about if you state too much? It asks for row and you answer 2,3 (row
      and column)? Boom again.
    </p>
    <p>That’s what we fixed here with <code>try/except</code>:</p>
    <pre><code>def choose_location(board, symbol):
    try:
        row = int(input(&quot;Choose which row: &quot;))

        row -= 1
        if row &lt; 0 or row &gt;= len(board):
            return False

        column = int(input(&quot;Choose which column: &quot;))
        column -= 1
        if column &lt; 0 or column &gt;= len(board[0]):
            return False

        cell = board[row][column]
        if cell is not None:
            return False

        board[row][column] = symbol
        return True
    except ValueError as ve:
        print(f&quot;Error: Cannot convert input to a number.&quot;)
        return False
    except Exception:
        # Not sure what else happened here, but didn&#39;t work.
        return False</code></pre>
    <p>
      For a more advanced version, you could edit the tic-tac-toe from files and
      make sure we have permissions to save to the files and that they are in a
      correct format for <code>json</code> to read and so on.
    </p>
    <p>
      See
      <a href="./tictactoe_errors_handled.py">tictactoe_errors_handled.py</a>
    </p>
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