add ex52 slices

build.zig

@@ -268,7 +268,10 @@ const exercises = [_]Exercise{
         .main_file = "51_values.zig",
         .output = "1:false!. 2:true!. 3:true!. XP before:0, after:200.",
     },
-    // 52 slices!
+    .{
+        .main_file = "52_slices.zig",
+        .output = "Hand1: A 4 K 8 Hand2: 5 2 Q J",
+    },
 };
 
 /// Check the zig version to make sure it can compile the examples properly.

exercises/52_slices.zig

@@ -0,0 +1,49 @@
+//
+// We've seen that passing arrays around can be awkward. Perhaps you
+// remember a particularly horrendous function definition from quiz3?
+// This function can only take arrays that are exactly 4 items long!
+//
+//     fn printPowersOfTwo(numbers: [4]u16) void { ... }
+//
+// That's the trouble with arrays - their size is part of the data
+// type and must be hard-coded into every usage of that type. This
+// digits array is a [10]u8 forever and ever:
+//
+//     var digits = [10]u8{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+//
+// Thankfully, Zig has slices, which let you dynamically point to a
+// start item and provide a length. Here are slices of our digit
+// array:
+//
+//     const foo = digits[0..1];  // 0
+//     const bar = digits[3..9];  // 3 4 5 6 7 8
+//     const all = digits[0..];   // 0 1 2 3 4 5 6 7 8 9
+//
+// As you can see, a slice [x..y] defines a first item by index x and
+// a length y (where y-1 is the index of the last item). Leaving y off
+// gives you the rest of the items.
+//
+// Notice that the type of a slice on an array of u8 items is []u8.
+//
+const std = @import("std");
+
+pub fn main() void {
+    var cards = [8]u8{ 'A', '4', 'K', '8', '5', '2', 'Q', 'J' };
+
+    // Please put the first 4 cards in hand1 and the rest in hand2.
+    const hand1: []u8 = cards[???];
+    const hand2: []u8 = cards[???];
+
+    std.debug.print("Hand1: ", .{});
+    printHand(hand1);
+
+    std.debug.print("Hand2: ", .{});
+    printHand(hand2);
+}
+
+// Please lend this function a hand. A u8 slice hand, that is.
+fn printHand(hand: ???) void {
+    for (hand) |h| {
+        std.debug.print("{u} ", .{h});
+    }
+}

patches/patches/52_slices.patch

@@ -0,0 +1,10 @@
+34,35c34,35
+<     const hand1: []u8 = cards[???];
+<     const hand2: []u8 = cards[???];
+---
+>     const hand1: []u8 = cards[0..4];
+>     const hand2: []u8 = cards[4..];
+45c45
+< fn printHand(hand: ???) void {
+---
+> fn printHand(hand: []u8) void {