Practice

In the previous practice session, a function was written to display the game board and code for the first player's move. In this lesson, players will take turns making moves.

Requirements

players must take turns
before each move, the player should see the message Player {player name} makes a move:
record the players' moves
after each move, display the game board

Source code

The following code should remain from the previous practice session:


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string[] board = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8" };
PrintBoard(board);
// player makes a move
Console.Write("Player Julia makes a move: ");
string input = Console.ReadLine();
int idx = Convert.ToInt32(input);
board[idx] = "J";
PrintBoard(board);
void PrintBoard(string[] board)
{
    Console.WriteLine($"|{board[0]}| |{board[1]}| |{board[2]}|");
    Console.WriteLine($"|{board[3]}| |{board[4]}| |{board[5]}|");
    Console.WriteLine($"|{board[6]}| |{board[7]}| |{board[8]}|");
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Implementation

Since the game board has 9 cells, the maximum number of moves will be 9. For this, you can use a for loop:


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// rest of the code omitted for brevity
for (int i = 0; i < board.Length; i++)
{
    // player move logic will go here
}
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Julia moves first, so she will move on even indices, and Dima on odd ones:


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// rest of the code omitted for brevity
for (int i = 0; i < board.Length; i++)
{
    if (i % 2 == 0)
    {
        // Julia's turn
    }
    else
    {
        // Dima's turn
    }
}
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Julia's move is already written; Dima's needs a small change:


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// rest of the code omitted for brevity
for (int i = 0; i < board.Length; i++)
{
    if (i % 2 == 0)
    {
        // Julia's turn
        Console.Write("Player Julia makes a move: ");
        string input = Console.ReadLine();
        int idx = Convert.ToInt32(input);
        board[idx] = "J";
        PrintBoard(board); // after each move, display the game board
    }
    else
    {
        // Dima's turn
        Console.Write("Player Dima makes a move: ");
        string input = Console.ReadLine();
        int idx = Convert.ToInt32(input);
        board[idx] = "D";
        PrintBoard(board); // after each move, display the game board
    }
}
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Final code

At the end of the lesson, you should have the following code:


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string[] board = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8" };
PrintBoard(board);
for (int i = 0; i < board.Length; i++)
{
    if (i % 2 == 0)
    {
        // Julia's turn
        Console.Write("Player Julia makes a move: ");
        string input = Console.ReadLine();
        int idx = Convert.ToInt32(input);
        board[idx] = "J";
        PrintBoard(board); // after each move, display the game board
    }
    else
    {
        // Dima's turn
        Console.Write("Player Dima makes a move: ");
        string input = Console.ReadLine();
        int idx = Convert.ToInt32(input);
        board[idx] = "D";
        PrintBoard(board); // after each move, display the game board
    }
}
Console.Write("Game over!");
void PrintBoard(string[] board)
{
    Console.WriteLine($"|{board[0]}| |{board[1]}| |{board[2]}|");
    Console.WriteLine($"|{board[3]}| |{board[4]}| |{board[5]}|");
    Console.WriteLine($"|{board[6]}| |{board[7]}| |{board[8]}|");
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Information

The program is not finished yet. Even if a player makes a winning move, the game will continue. This will be fixed in the next step.

Exercises

The function PrintBoard(board); is called after each player's move. If you move it to the end of the loop, the logic will not change, and the code will become cleaner. Place it after the else block and verify that the program still works the same way.


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The code for the players' moves is very similar and differs only in the player's name. A great idea is to create another function. Write a function with the signature void PlayerMakesMove(string name), move the player move code into it, make a small change, and verify that the program behavior has not changed. Hint: you can get the first letter of the player's name like this: name.Substring(0, 1).


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