summaryrefslogtreecommitdiffstatshomepage
path: root/exercises
diff options
context:
space:
mode:
Diffstat (limited to 'exercises')
-rw-r--r--exercises/46_optionals2.zig14
-rw-r--r--exercises/48_methods2.zig68
2 files changed, 81 insertions, 1 deletions
diff --git a/exercises/46_optionals2.zig b/exercises/46_optionals2.zig
index a037382..d3f65bb 100644
--- a/exercises/46_optionals2.zig
+++ b/exercises/46_optionals2.zig
@@ -5,11 +5,23 @@
// linked to the first elephant. This is because we had NO CONCEPT
// of a tail that didn't point to another elephant!
//
+// We also introduce the handy ".?" shortcut:
+//
+// const foo = bar.?;
+//
+// is the same as
+//
+// const foo = bar orelse unreachable;
+//
+// See if you can find where we use this shortcut below.
+//
+// Now let's make those elephant tails optional!
+//
const std = @import("std");
const Elephant = struct {
letter: u8,
- tail: *Elephant = null, // <---- make this optional!
+ tail: *Elephant = null, // Hmm... tail needs something...
visited: bool = false,
};
diff --git a/exercises/48_methods2.zig b/exercises/48_methods2.zig
new file mode 100644
index 0000000..b9477da
--- /dev/null
+++ b/exercises/48_methods2.zig
@@ -0,0 +1,68 @@
+//
+// Now that we've seen how methods work, let's see if we can help
+// our elephants out a bit more with some Elephant methods.
+//
+const std = @import("std");
+
+const Elephant = struct {
+ letter: u8,
+ tail: ?*Elephant = null,
+ visited: bool = false,
+
+ // New Elephant methods!
+ pub fn getTail(self: *Elephant) *Elephant {
+ return self.tail.?; // Remember, this is means "orelse unreachable"
+ }
+
+ pub fn hasTail(self: *Elephant) bool {
+ return (self.tail != null);
+ }
+
+ pub fn visit(self: *Elephant) void {
+ self.visited = true;
+ }
+
+ pub fn print(self: *Elephant) void {
+ // Prints elephant letter and (V)isited or (U)nvisited.
+ var v: u8 = if (self.visited) 'V' else 'U';
+ std.debug.print("Elephant {u} ({u}). ", .{ self.letter, v});
+ }
+};
+
+pub fn main() void {
+ var elephantA = Elephant{ .letter = 'A' };
+ var elephantB = Elephant{ .letter = 'B' };
+ var elephantC = Elephant{ .letter = 'C' };
+
+ // Link the elephants so that each tail "points" to the next.
+ elephantA.tail = &elephantB;
+ elephantB.tail = &elephantC;
+
+ visitElephants(&elephantA);
+
+ std.debug.print("\n", .{});
+}
+
+// This function visits all elephants once, starting with the
+// first elephant and following the tails to the next elephant.
+fn visitElephants(first_elephant: *Elephant) void {
+ var e = first_elephant;
+
+ while (true) {
+ e.print();
+ e.visit();
+
+ // Get the next elephant or stop.
+ if (e.hasTail()) {
+ e = e.???; // Which method do we want here?
+ } else {
+ break;
+ }
+ }
+}
+
+// Bonus: Zig's enums can also have methods! Can you find
+// one in the wild? If you can, mention it along with your
+// name or alias in a comment below this one and make a
+// pull request on GitHub for a piece of eternal Ziglings
+// glory. The first five (5) PRs will be accepted!