TicTacToe in the console

#include <stdio.h>

int turn; /* flag for the player's turn. 0 = player X, 1 = player O */
char* board[9]; /* cells in the tic-tac-toe board */

/* get input from the user for what cell to play in */
int get_input() {
    /* get user input */
    printf("Position to play: ");
    int pos;
    scanf("%d", &pos);
    pos--;

    /* error check the input */
    if (pos < 0 || pos > 8) {
        printf("Invalid position (choose between 1 and 9)\n");
        return get_input();
    }

    /* make sure nobody has played in the cell before */
    if (board[pos] != "-") {
        printf("Somebody has already played there. Try again...\n");
        return get_input();
    }

    return pos;
}

/* display game board to the console */
void display_board() {
    for (int x=0; x<9; x++) {
        /* new line after every 3 cells to form the grid output */
        if (x > 0 && x % 3 == 0) {
            printf("\n");
        }

        /* print either X or O depending whats in the cell. */
        /* print the cell number if the cell is empty */
        if (board[x] == "-") {
            printf("%d ", x+1);
        } else {
            printf("%s ", board[x]);
        }
    }

    printf("\n\n");
}

/* make a player move (place X or O in a cell) */
void make_move(int pos) {
    board[pos] = turn ? "O" : "X";
    turn = !turn;
}

/* check if the game is over */
int game_over() {
    /* horizontal wins */
    if (board[0] != "-" && board[0] == board[1] && board[1] == board[2]) {
        printf("Player %s has won!\n", board[0]);
        return 1;
    }
    if (board[3] != "-" && board[3] == board[4] && board[4] == board[5]) {
        printf("Player %s has won!\n", board[3]);
        return 1;
    }
    if (board[5] != "-" && board[5] == board[6] && board[6] == board[7]) {
        printf("Player %s has won!\n", board[5]);
        return 1;
    }

    /* vertical wins */
    if (board[0] != "-" && board[0] == board[3] && board[3] == board[6]) {
        printf("Player %s has won!\n", board[0]);
        return 1;
    }
    if (board[1] != "-" && board[1] == board[4] && board[4] == board[7]) {
        printf("Player %s has won!\n", board[1]);
        return 1;
    }
    if (board[2] != "-" && board[2] == board[5] && board[5] == board[8]) {
        printf("Player %s has won!\n", board[2]);
        return 1;
    }

    /* diagonal wins */
    if (board[0] != "-" && board[0] == board[4] && board[4] == board[8]) {
        printf("Player %s has won!\n", board[0]);
        return 1;
    }
    if (board[2] != "-" && board[2] == board[4] && board[4] == board[6]) {
        printf("Player %s has won!\n", board[2]);
        return 1;
    }

    /* its a tie when all cells are filled */
    for (int i=0; i<9; i++) {
        if (board[i] == "-") {
            return 0;
        }
    }
    printf("It's a tie!\n");
    return 1;
}

int main() {
    /* setup default game board */
    for (int i=0; i<9; i++) {
        board[i] = "-";
    }

    printf("Welcome to Tie-Tac-Toe\n");
    printf("Player X will go first.\n\n");
    display_board();

    /* game loop until somebody wins or you both tie */
    while (!game_over()) {
        int position = get_input();
        make_move(position);
        display_board();
    }

    printf("The game has ended.\n");
}