Add Zig implementation

zig/src/main.zig

@@ -0,0 +1,43 @@
+const std = @import("std");
+const gilded_rose = @import("gilded_rose.zig");
+const Item = gilded_rose.Item;
+const GildedRose = gilded_rose.GildedRose;
+
+pub fn main() !void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+
+    const args = try std.process.argsAlloc(allocator);
+    var days: u8 = 2;
+    if (args.len >= 2) {
+        days = try std.fmt.parseInt(u8, args[1], 10);
+    }
+
+    var items = [_]Item{
+        Item.init("+5 Dexterity Vest", 10, 20),
+        Item.init("Aged Brie", 2, 0),
+        Item.init("Elixir of the Mongoose", 5, 7),
+        Item.init("Sulfuras, Hand of Ragnaros", 0, 80),
+        Item.init("Sulfuras, Hand of Ragnaros", -1, 80),
+        Item.init("Backstage passes to a TAFKAL80ETC concert", 15, 20),
+        Item.init("Backstage passes to a TAFKAL80ETC concert", 10, 49),
+        Item.init("Backstage passes to a TAFKAL80ETC concert", 5, 49),
+        // this Conjured item doesn't yet work properly
+        Item.init("Conjured Mana Cake", 3, 6),
+    };
+    var app = GildedRose.init(&items);
+
+    const stdout = std.io.getStdOut().writer();
+    try stdout.print("OMGHAI!\n", .{});
+
+    for (0..days + 1) |day| {
+        try stdout.print("-------- day {d} --------\n", .{day});
+        try stdout.print("name, sellIn, quality\n", .{});
+        for (items) |item| {
+            try stdout.print("{s}, {d}, {d}\n", .{ item.name, item.sell_in, item.quality });
+        }
+        try stdout.print("\n", .{});
+        _ = app.updateQuality();
+    }
+}