tic-tac-toe.zig

const std = @import("std");
const warn = std.debug.warn;

var board = [_]u8{'_'} ** 9;

fn askUserInput() !void {
    const stdin = std.io.getStdIn().inStream();
    while (true) {
        warn("Your turn, choose your move:\n", .{});
        const player_move = try stdin.readIntNative(u8);
        if (player_move >= '1' and player_move <= '9') {
            const board_field = player_move - '0' - 1;
            if (board[board_field] != '_') {
                const cell_value = [1:0]u8{board[board_field]};
                warn("Wrong board position, this cell is already {}\n", .{cell_value});
            } else {
                board[board_field] = 'O';
                return;
            }
        } else {
            warn("Wrong number, please write number from 1 to 9\n", .{});
        }
    }
}

pub fn main() !void {
    // Pressing "a" and then Enter, which is invalid input renders this:
    //
    // Wrong number, please write number from 1 to 9
    // Your turn, choose your move:
    // Wrong number, please write number from 1 to 9
    // Your turn, choose your move:
    //
    // Why does it render these messages twice? Pressing Enter
    // without "a" renders it just once.
    try askUserInput();
}