用用户输入的字符替换下划线（在C中）

Question

This is for Homework

I have to program a game of TicTacToe and the only issue I have left is formatting. Here is my function for the matrix where the user and computer have to enter their O's and X's in.

void the_matrix() { // Like the movie
//Get rid of the underscores 

 int m;

printf("The current state of the board:\n");
 for (m = 0; m < 3; m++) {
printf("%c_ %c_ %c_\n", table[m][0], table[m][1], table[m][2]);
  }
printf("\n");
}

So the project calls for the compiler to display the game like this(I'm only showing what the first row should look like on this post for simplicity.):

"_ _ _" [Ignore the quotation marks]

then the user enter 'O' for the (1,1) position

O _ _.

When I run my program it looks like this

O_ _ _

I know why the program's doing that, it's because my printf statement set it up to be that way. But my question is how would I swap the underscore with an O or and X so the underscore wouldn't be displayed.

Any help would be appreicated!

Answer 1

printf ("%c_") will print a character followed by an underscore.

What you need is to printf ("%c") and the argument should decide if you print an O, and X, or an underscore.

On second thought, the easiest thing to do is probably to initialize your array to have _ in every space, and your logic should recognize that as "empty". Then you can just print the character that appears in your array.

Answer 2

I'd distinguish the logic/state of the board from the way you display it. So the values of the board could have a clear meaning, like 0 for blank, 1 for player 1, and 2 for player 2, whereas the way you print it may be different then depending on whether you have a GUI or a terminal. And especially your algorithms will not depend on display issues, eg you will not have to change your algorithms just because you decide to display a blank field by a . instead of a - :

See the following code illustrating this approach:

typedef enum {
    BLANK = 0,
    PLAYER1 = 1,
    PLAYER2 = 2
} BoardValue;

BoardValue table[3][3] = { BLANK };

char displayValue(int state) {
    return (state == PLAYER1 ? 'O' : (state == PLAYER2 ? 'X' : '-'));
}

void the_matrix() { // Like the movie
    //Get rid of the underscores

    int m;

    printf("The current state of the board:\n");
    for (m = 0; m < 3; m++) {
        printf("%c %c %c\n", displayValue(table[m][0]), displayValue(table[m][1]), displayValue(table[m][2]));
    }
    printf("\n");
}


int main() {

    table[0][0] = PLAYER1;
    table[1][1] = PLAYER2;

    the_matrix();
}