Tic Tac Toe in Zig

tictactoe.zig

const std = @import("std");
const stdout = std.io.getStdOut().writer();
const stdin = std.io.getStdIn().reader();
const print = stdout.print;

const trit = enum(u2) { e, x, o, d };

const field = [9]trit;

var inb: u8 = 0;
var play: u8 = 10;
var turnx = true;
var winner: trit  = .e;
var board: field = .{ .e, .e, .e, .e, .e, .e, .e, .e, .e };

fn win(f: field, who: trit) bool {
    const check = .{
        .{ 0, 1, 2 },
        .{ 3, 4, 5 },
        .{ 6, 7, 8 },
        .{ 0, 4, 8 },
        .{ 6, 4, 2 },
        .{ 0, 3, 6 },
        .{ 1, 4, 7 },
        .{ 2, 5, 8 },
    };
    inline for (check) |c| {
        if (f[c[0]] == who and f[c[1]] == who and f[c[2]] == who) return true;
    }
    return false;
}

fn showfield(f: field) void {
    for (f) |c, i| {
        if (c == .e) print("{d}", .{i}) catch unreachable
        else if (c == .x) print("x", .{}) catch unreachable
        else if (c == .o) print("o", .{}) catch unreachable;
        if (i % 3 == 2) print("\n", .{}) catch unreachable;
    }
}

pub fn main() !void {
    var i: u8 = 0;
    while (winner == .e) {
        showfield(board);
        play = 10; // guarantee that the while loop will run at least once
        var turns = if (turnx) "x" else "o";
        try print("Give a number for {s} to play on: ", .{turns});
        while (play > 8) { // discard everything that is not a valid board number
            inb = try stdin.readByte();
            play = inb -% '0'; // convert ascii/utf-8 to number
        }
        while (inb != '\n') { // don't permit inputting the whole game at once
            inb = try stdin.readByte();
        }
        if (board[play] == .e) {
            if (turnx) board[play] = .x
            else board[play] = .o;
            turnx = !turnx;
        }

        i += 1;
        if (i > 8) { // last turn, if the last turn makes a win, the last check should overwrite it
            winner = .d;
        }
        for (std.enums.values(trit)) |t| {
            if (win(board, t)) winner = t;
        }
    }
    try switch (winner) {
        .x => print("x has won!\n", .{}),
        .o => print("o has won!\n", .{}),
        .d => print("it's a draw!\n", .{}),
        .e => unreachable,
    };
    showfield(board);
}