91 files changed, 217 insertions(+), 183 deletions(-)

M exercises/001_hello.zig
M exercises/002_std.zig
M exercises/003_assignment.zig
M exercises/004_arrays.zig
M exercises/005_arrays2.zig
M exercises/006_strings.zig
M exercises/007_strings2.zig
M exercises/008_quiz.zig
M exercises/009_if.zig
M exercises/010_if2.zig
M exercises/011_while.zig
M exercises/012_while2.zig
M exercises/013_while3.zig
M exercises/014_while4.zig
M exercises/015_for.zig
M exercises/016_for2.zig
M exercises/017_quiz2.zig
M exercises/018_functions.zig
M exercises/019_functions2.zig
M exercises/020_quiz3.zig
M exercises/021_errors.zig
M exercises/022_errors2.zig
M exercises/023_errors3.zig
M exercises/024_errors4.zig
M exercises/025_errors5.zig
M exercises/026_hello2.zig
M exercises/027_defer.zig
M exercises/028_defer2.zig
M exercises/029_errdefer.zig
M exercises/030_switch.zig
M exercises/031_switch2.zig
M exercises/032_unreachable.zig
M exercises/033_iferror.zig
M exercises/034_quiz4.zig
M exercises/035_enums.zig
M exercises/036_enums2.zig
M exercises/037_structs.zig
M exercises/038_structs2.zig
M exercises/039_pointers.zig
M exercises/040_pointers2.zig
M exercises/041_pointers3.zig
M exercises/042_pointers4.zig
M exercises/043_pointers5.zig
M exercises/044_quiz5.zig
M exercises/045_optionals.zig
M exercises/046_optionals2.zig
M exercises/047_methods.zig
M exercises/048_methods2.zig
M exercises/049_quiz6.zig
M exercises/050_no_value.zig
M exercises/051_values.zig
M exercises/052_slices.zig
M exercises/053_slices2.zig
M exercises/054_manypointers.zig
M exercises/055_unions.zig
M exercises/056_unions2.zig
M exercises/057_unions3.zig
M exercises/058_quiz7.zig
M exercises/059_integers.zig
M exercises/060_floats.zig
M exercises/061_coercions.zig
M exercises/062_loop_expressions.zig
M exercises/063_labels.zig
M exercises/064_builtins.zig
M exercises/065_builtins2.zig
M exercises/066_comptime.zig
M exercises/067_comptime2.zig
M exercises/068_comptime3.zig
M exercises/069_comptime4.zig
M exercises/070_comptime5.zig
M exercises/071_comptime6.zig
M exercises/072_comptime7.zig
M exercises/073_comptime8.zig
M exercises/074_comptime9.zig
M exercises/075_quiz8.zig
M exercises/076_sentinels.zig
M exercises/077_sentinels2.zig
M exercises/078_sentinels3.zig
M exercises/079_quoted_identifiers.zig
M exercises/080_anonymous_structs.zig
M exercises/081_anonymous_structs2.zig
M exercises/082_anonymous_structs3.zig
M exercises/083_anonymous_lists.zig
M exercises/084_async.zig
M exercises/085_async2.zig
M exercises/086_async3.zig
M exercises/087_async4.zig
M exercises/088_async5.zig
M exercises/089_async6.zig
M exercises/090_async7.zig
M exercises/091_async8.zig

@@ 16,6 16,6 @@
 //
 const std = @import("std");
 
-fn main() void {
+pub fn main() void {
     std.debug.print("Hello world!\n", .{});
 }

@@ 11,7 11,7 @@
 // Please complete the import below:
 //
 
-??? = @import("std");
+const std = @import("std");
 
 pub fn main() void {
     std.debug.print("Standard Library.\n", .{});

@@ 34,12 34,12 @@
 const std = @import("std");
 
 pub fn main() void {
-    const n: u8 = 50;
+    var n: u8 = 50;
     n = n + 5;
 
-    const pi: u8 = 314159;
+    const pi: u32 = 314159;
 
-    const negative_eleven: u8 = -11;
+    const negative_eleven: i8 = -11;
 
     // There are no errors in the next line, just explanation:
     // Perhaps you noticed before that the print function takes two

@@ 27,7 27,7 @@ pub fn main() void {
     // (Problem 1)
     // This "const" is going to cause a problem later - can you see what it is?
     // How do we fix it?
-    const some_primes = [_]u8{ 1, 3, 5, 7, 11, 13, 17, 19 };
+    var some_primes = [_]u8{ 1, 3, 5, 7, 11, 13, 17, 19 };
 
     // Individual values can be set with '[]' notation.
     // Example: This line changes the first prime to 2 (which is correct):


@@ 40,11 40,11 @@ pub fn main() void {
     // (Problem 2)
     // Looks like we need to complete this expression. Use the example
     // above to set "fourth" to the fourth element of the some_primes array:
-    const fourth = some_primes[???];
+    const fourth = some_primes[3];
 
     // (Problem 3)
     // Use the len property to get the length of the array:
-    const length = some_primes.???;
+    const length = some_primes.len;
 
     std.debug.print("First: {}, Fourth: {}, Length: {}\n", .{
         first, fourth, length,

@@ 20,12 20,12 @@ pub fn main() void {
     // (Problem 1)
     // Please set this array concatenating the two arrays above.
     // It should result in: 1 3 3 7
-    const leet = ???;
+    const leet = le ++ et;
 
     // (Problem 2)
     // Please set this array using repetition.
     // It should result in: 1 0 0 1 1 0 0 1 1 0 0 1
-    const bit_pattern = [_]u8{ ??? } ** 3;
+    const bit_pattern = [_]u8{ 1, 0, 0, 1 } ** 3;
 
     // Okay, that's all of the problems. Let's see the results.
     //

@@ 22,18 22,18 @@ pub fn main() void {
     // (Problem 1)
     // Use array square bracket syntax to get the letter 'd' from
     // the string "stardust" above.
-    const d: u8 = ziggy[???];
+    const d: u8 = ziggy[4];
 
     // (Problem 2)
     // Use the array repeat '**' operator to make "ha ha ha ".
-    const laugh = "ha " ???;
+    const laugh = "ha " ** 3;
 
     // (Problem 3)
     // Use the array concatenation '++' operator to make "Major Tom".
     // (You'll need to add a space as well!)
     const major = "Major";
     const tom = "Tom";
-    const major_tom = major ??? tom;
+    const major_tom = major ++ [_]u8{' '} ++ tom;
 
     // That's all the problems. Let's see our results:
     std.debug.print("d={u} {s}{s}\n", .{ d, laugh, major_tom });

@@ 15,9 15,9 @@ const std = @import("std");
 
 pub fn main() void {
     const lyrics =
-        Ziggy played guitar
-        Jamming good with Andrew Kelley
-        And the Spiders from Mars
+        \\Ziggy played guitar
+        \\Jamming good with Andrew Kelley
+        \\And the Spiders from Mars
     ;
 
     std.debug.print("{s}\n", .{lyrics});

@@ 19,7 19,7 @@ pub fn main() void {
     // the idiomatic type to use for array indexing.
     //
     // There IS a problem on this line, but 'usize' isn't it.
-    const x: usize = 1;
+    var x: usize = 1;
 
     // Note: When you want to declare memory (an array in this
     // case) without putting anything in it, you can set it to


@@ 33,10 33,10 @@ pub fn main() void {
     lang[0] = letters[x];
 
     x = 3;
-    lang[???] = letters[x];
+    lang[1] = letters[x];
 
-    x = ???;
-    lang[2] = letters[???];
+    x = 5;
+    lang[2] = letters[x];
 
     // We want to "Program in Zig!" of course:
     std.debug.print("Program in {s}!\n", .{lang});

@@ 24,7 24,7 @@ pub fn main() void {
     const foo = 1;
 
     // Please fix this condition:
-    if (foo) {
+    if (foo == 1) {
         // We want our program to print this message!
         std.debug.print("Foo is 1!\n", .{});
     } else {

@@ 10,7 10,7 @@ pub fn main() void {
 
     // Please use an if...else expression to set "price".
     // If discount is true, the price should be $17, otherwise $20:
-    var price: u8 = if ???;
+    var price: u8 = if (discount) 17 else 20;
 
     std.debug.print("With the discount, the price is ${}.\n", .{price});
 }

@@ 21,7 21,7 @@ pub fn main() void {
     var n: u32 = 2;
 
     // Please use a condition that is true UNTIL "n" reaches 1024:
-    while (???) {
+    while (n < 1024) {
         // Print the current number
         std.debug.print("{} ", .{n});
 

@@ 25,7 25,7 @@ pub fn main() void {
 
     // Please set the continue expression so that we get the desired
     // results in the print statement below.
-    while (n < 1000) : ??? {
+    while (n < 1000) : (n *= 2) {
         // Print the current number
         std.debug.print("{} ", .{n});
     }

@@ 24,8 24,8 @@ pub fn main() void {
     while (n <= 20) : (n += 1) {
         // The '%' symbol is the "modulo" operator and it
         // returns the remainder after division.
-        if (n % 3 == 0) ???;
-        if (n % 5 == 0) ???;
+        if (n % 3 == 0) continue;
+        if (n % 5 == 0) continue;
         std.debug.print("{} ", .{n});
     }
 

@@ 18,7 18,7 @@ pub fn main() void {
     // Oh dear! This while loop will go forever?!
     // Please fix this so the print statement below gives the desired output.
     while (true) : (n += 1) {
-        if (???) ???;
+        if (n == 4) break;
     }
 
     // Result: we want n=4

@@ 15,7 15,7 @@ pub fn main() void {
 
     std.debug.print("A Dramatic Story: ", .{});
 
-    for (???) |???| {
+    for (story) |scene| {
         if (scene == 'h') std.debug.print(":-)  ", .{});
         if (scene == 's') std.debug.print(":-(  ", .{});
         if (scene == 'n') std.debug.print(":-|  ", .{});

@@ 24,7 24,7 @@ pub fn main() void {
     // the value of the place as a power of two for each bit.
     //
     // See if you can figure out the missing piece:
-    for (bits) |bit, ???| {
+    for (bits) |bit, i| {
         // Note that we convert the usize i to a u32 with
         // @intCast(), a builtin function just like @import().
         // We'll learn about these properly in a later exercise.

@@ 9,18 9,18 @@
 // Let's go from 1 to 16.  This has been started for you, but there's
 // some problems. :-(
 //
-const std = import standard library;
+const std = @import("std");
 
-function main() void {
+pub fn main() void {
     var i: u8 = 1;
     var stop_at: u8 = 16;
 
     // What kind of loop is this? A 'for' or a 'while'?
-    ??? (i <= stop_at) : (i += 1) {
+    while (i <= stop_at) : (i += 1) {
         if (i % 3 == 0) std.debug.print("Fizz", .{});
         if (i % 5 == 0) std.debug.print("Buzz", .{});
         if (!(i % 3 == 0) and !(i % 5 == 0)) {
-            std.debug.print("{}", .{???});
+            std.debug.print("{}", .{i});
         }
         std.debug.print(", ", .{});
     }

@@ 25,6 25,6 @@ pub fn main() void {
 // We're just missing a couple things. One thing we're NOT missing is the
 // keyword "pub", which is not needed here. Can you guess why?
 //
-??? deepThought() ??? {
+fn deepThought() u8 {
     return 42; // Number courtesy Douglas Adams
 }

@@ 22,7 22,7 @@ pub fn main() void {
 // You'll need to figure out the parameter name and type that we're
 // expecting. The output type has already been specified for you.
 //
-fn twoToThe(???) u32 {
+fn twoToThe(my_number: u32) u32 {
     return std.math.pow(u32, 2, my_number);
     // std.math.pow(type, a, b) takes a numeric type and two
     // numbers of that type (or that can coerce to that type) and

@@ 8,7 8,7 @@
 const std = @import("std");
 
 pub fn main() void {
-    const my_numbers = [4]u16{ 5, 6, 7, 8 };
+    const my_numbers: [4]u16 = [4]u16{ 5, 6, 7, 8 };
 
     printPowersOfTwo(my_numbers);
     std.debug.print("\n", .{});


@@ 21,8 21,8 @@ pub fn main() void {
 //
 // This function prints, but does not return anything.
 //
-fn printPowersOfTwo(numbers: [4]u16) ??? {
-    loop (numbers) |n| {
+fn printPowersOfTwo(numbers: [4]u16) void {
+    for (numbers) |n| {
         std.debug.print("{} ", .{twoToThe(n)});
     }
 }


@@ 31,13 31,13 @@ fn printPowersOfTwo(numbers: [4]u16) ??? {
 // exercise. But don't be fooled! This one does the math without the aid
 // of the standard library!
 //
-fn twoToThe(number: u16) ??? {
+fn twoToThe(number: u16) u16 {
     var n: u16 = 0;
     var total: u16 = 1;
 
-    loop (n < number) : (n += 1) {
+    while (n < number) : (n += 1) {
         total *= 2;
     }
 
-    return ???;
+    return total;
 }

@@ 9,7 9,7 @@
 // "TooSmall". Please add it where needed!
 const MyNumberError = error{
     TooBig,
-    ???,
+    TooSmall,
     TooFour,
 };
 


@@ 26,7 26,7 @@ pub fn main() void {
         if (number_error == MyNumberError.TooBig) {
             std.debug.print(">4. ", .{});
         }
-        if (???) {
+        if (number_error == MyNumberError.TooSmall) {
             std.debug.print("<4. ", .{});
         }
         if (number_error == MyNumberError.TooFour) {

@@ 19,7 19,7 @@ const std = @import("std");
 const MyNumberError = error{TooSmall};
 
 pub fn main() void {
-    var my_number: ??? = 5;
+    var my_number: MyNumberError!u8 = 5;
 
     // Looks like my_number will need to either store a number OR
     // an error. Can you set the type correctly above?

@@ 12,14 12,14 @@ const MyNumberError = error{TooSmall};
 
 pub fn main() void {
     var a: u32 = addTwenty(44) catch 22;
-    var b: u32 = addTwenty(4) ??? 22;
+    var b: u32 = addTwenty(4) catch 22;
 
     std.debug.print("a={}, b={}\n", .{ a, b });
 }
 
 // Please provide the return type from this function.
 // Hint: it'll be an error union.
-fn addTwenty(n: u32) ??? {
+fn addTwenty(n: u32) MyNumberError!u32 {
     if (n < 5) {
         return MyNumberError.TooSmall;
     } else {

@@ 59,7 59,13 @@ fn fixTooSmall(n: u32) MyNumberError!u32 {
     // If we get a TooSmall error, we should return 10.
     // If we get any other error, we should return that error.
     // Otherwise, we return the u32 number.
-    return detectProblems(n) ???;
+    return detectProblems(n) catch |err| {
+        if (err == MyNumberError.TooSmall) {
+            return 10;
+        }
+
+        return err;
+    };
 }
 
 fn detectProblems(n: u32) MyNumberError!u32 {

@@ 26,7 26,7 @@ fn addFive(n: u32) MyNumberError!u32 {
     // This function needs to return any error which might come back from detect().
     // Please use a "try" statement rather than a "catch".
     //
-    var x = detect(n);
+    var x = try detect(n);
 
     return x + 5;
 }

@@ 19,5 19,5 @@ pub fn main() !void {
     // to be able to pass it up as a return value of main().
     //
     // We just learned of a single statement which can accomplish this.
-    stdout.print("Hello world!\n", .{});
+    try stdout.print("Hello world!\n", .{});
 }

@@ 20,6 20,6 @@ const std = @import("std");
 pub fn main() void {
     // Without changing anything else, please add a 'defer' statement
     // to this code so that our program prints "One Two\n":
-    std.debug.print("Two\n", .{});
+    defer std.debug.print("Two\n", .{});
     std.debug.print("One ", .{});
 }

@@ 18,7 18,7 @@ pub fn main() void {
 fn printAnimal(animal: u8) void {
     std.debug.print("(", .{});
 
-    std.debug.print(") ", .{}); // <---- how?!
+    defer std.debug.print(") ", .{}); // <---- how?!
 
     if (animal == 'g') {
         std.debug.print("Goat", .{});

@@ 32,7 32,7 @@ fn makeNumber() MyErr!u32 {
 
     // Please make the "failed" message print ONLY if the makeNumber()
     // function exits with an error:
-    std.debug.print("failed!\n", .{});
+    errdefer std.debug.print("failed!\n", .{});
 
     var num = try getNumber(); // <-- This could fail!
 

@@ 46,6 46,9 @@ pub fn main() void {
             // match for every possible value).  Please add an "else"
             // to this switch to print a question mark "?" when c is
             // not one of the existing matches.
+            else => {
+                std.debug.print("?", .{});
+            },
         }
     }
 

@@ 29,6 29,7 @@ pub fn main() void {
             // ...
             25 => 'Y',
             26 => 'Z',
+            else => '!',
             // As in the last exercise, please add the 'else' clause
             // and this time, have it return an exclamation mark '!'.
         };

@@ 35,6 35,7 @@ pub fn main() void {
             3 => {
                 current_value *= current_value;
             },
+            else => unreachable,
         }
 
         std.debug.print("{} ", .{current_value});

@@ 39,6 39,7 @@ pub fn main() void {
             std.debug.print("={}. ", .{value});
         } else |err| switch (err) {
             MyNumberError.TooBig => std.debug.print(">4. ", .{}),
+            MyNumberError.TooSmall => std.debug.print("<4. ", .{}),
             // Please add a match for TooSmall here and have it print: "<4. "
         }
     }

@@ 12,9 12,12 @@ const NumError = error{IllegalNumber};
 pub fn main() void {
     const stdout = std.io.getStdOut().writer();
 
-    const my_num: u32 = getNumber();
+    var my_num: u32 = getNumber() catch 42;
 
-    try stdout.print("my_num={}\n", .{my_num});
+    stdout.print("my_num={}\n", .{my_num}) catch {
+        std.debug.print("a={}\n", .{my_num});
+        return;
+    };
 }
 
 // This function is obviously weird and non-functional. But you will not be changing it for this quiz.

@@ 20,7 20,7 @@
 const std = @import("std");
 
 // Please complete the enum!
-const Ops = enum { ??? };
+const Ops = enum { inc, pow, dec };
 
 pub fn main() void {
     const operations = [_]Ops{

@@ 31,7 31,7 @@ const std = @import("std");
 const Color = enum(u32) {
     red = 0xff0000,
     green = 0x00ff00,
-    blue = ???,
+    blue = 0x0000ff,
 };
 
 pub fn main() void {


@@ 53,12 53,12 @@ pub fn main() void {
         \\<p>
         \\  <span style="color: #{x:0>6}">Red</span>
         \\  <span style="color: #{x:0>6}">Green</span>
-        \\  <span style="color: #{}">Blue</span>
+        \\  <span style="color: #{x:0>6}">Blue</span>
         \\</p>
         \\
     , .{
         @enumToInt(Color.red),
         @enumToInt(Color.green),
-        @enumToInt(???), // Oops! We're missing something!
+        @enumToInt(Color.blue), // Oops! We're missing something!
     });
 }

@@ 36,6 36,7 @@ const Character = struct {
     class: Class,
     gold: u32,
     experience: u32,
+    health: u8,
 };
 
 pub fn main() void {


@@ 44,6 45,7 @@ pub fn main() void {
         .class = Class.wizard,
         .gold = 20,
         .experience = 10,
+        .health = 100,
     };
 
     // Glorp gains some gold.

@@ 33,6 33,13 @@ pub fn main() void {
         .experience = 10,
     };
 
+    chars[1] = Character{
+        .class = Class.wizard,
+        .gold = 10,
+        .health = 100,
+        .experience = 20,
+    };
+
     // Please add "Zump the Loud" with the following properties:
     //
     //     class      bard

@@ 30,7 30,7 @@ pub fn main() void {
 
     // Please make num2 equal 5 using num1_pointer!
     // (See the "cheatsheet" above for ideas.)
-    num2 = ???;
+    num2 = num1_pointer.*;
 
     std.debug.print("num1: {}, num2: {}\n", .{ num1, num2 });
 }

@@ 20,7 20,7 @@
 const std = @import("std");
 
 pub fn main() void {
-    const a: u8 = 12;
+    var a: u8 = 12;
     const b: *u8 = &a; // fix this!
 
     std.debug.print("a: {}, b: {}\n", .{ a, b.* });

@@ 31,7 31,7 @@ pub fn main() void {
 
     // Please define pointer "p" so that it can point to EITHER foo or
     // bar AND change the value it points to!
-    ??? p: ??? = undefined;
+    var p: *u8 = undefined;
 
     p = &foo;
     p.* += 1;

@@ 28,5 28,5 @@ pub fn main() void {
 // This function should take a reference to a u8 value and set it
 // to 5.
 fn makeFive(x: *u8) void {
-    ??? = 5; // fix me!
+    x.* = 5; // fix me!
 }

@@ 57,7 57,7 @@ pub fn main() void {
 
     // FIX ME!
     // Please pass our Character "glorp" to printCharacter():
-    printCharacter(???);
+    printCharacter(&glorp);
 }
 
 // Note how this function's "c" parameter is a pointer to a Character struct.

@@ 19,12 19,14 @@ const Elephant = struct {
 pub fn main() void {
     var elephantA = Elephant{ .letter = 'A' };
     // (Please add Elephant B here!)
+    var elephantB = Elephant{ .letter = 'B' };
     var elephantC = Elephant{ .letter = 'C' };
 
     // Link the elephants so that each tail "points" to the next elephant.
     // They make a circle: A->B->C->A...
     elephantA.tail = &elephantB;
     // (Please link Elephant B's tail to Elephant C here!)
+    elephantB.tail = &elephantC;
     elephantC.tail = &elephantA;
 
     visitElephants(&elephantA);

@@ 29,7 29,7 @@ pub fn main() void {
 
     // Please threaten the result so that answer is either the
     // integer value from deepThought() OR the number 42:
-    var answer: u8 = result;
+    var answer: u8 = result orelse 42;
 
     std.debug.print("The Ultimate Answer: {}.\n", .{answer});
 }

@@ 21,7 21,7 @@ const std = @import("std");
 
 const Elephant = struct {
     letter: u8,
-    tail: *Elephant = null, // Hmm... tail needs something...
+    tail: ?*Elephant = null, // Hmm... tail needs something...
     visited: bool = false,
 };
 


@@ 51,7 51,7 @@ fn visitElephants(first_elephant: *Elephant) void {
         // We should stop once we encounter a tail that
         // does NOT point to another element. What can
         // we put here to make that happen?
-        if (e.tail == null) ???;
+        if (e.tail == null) break;
 
         e = e.tail.?;
     }

@@ 84,7 84,7 @@ pub fn main() void {
         for (aliens) |*alien| {
 
             // *** Zap the Alien Here! ***
-            ???.zap(heat_ray_strength);
+            alien.zap(heat_ray_strength);
 
             // If the alien's health is still above 0, it's still alive.
             if (alien.health > 0) aliens_alive += 1;

@@ 54,7 54,7 @@ fn visitElephants(first_elephant: *Elephant) void {
 
         // This gets the next elephant or stops.
         if (e.hasTail()) {
-            e = e.???; // Which method do we want here?
+            e = e.getTail(); // Which method do we want here?
         } else {
             break;
         }

@@ 27,8 27,13 @@ const Elephant = struct {
     // Your Elephant trunk methods go here!
     // ---------------------------------------------------
 
-    ???
+    pub fn getTrunk(self: *Elephant) *Elephant {
+        return self.trunk.?; // Remember, this means "orelse unreachable"
+    }
 
+    pub fn hasTrunk(self: *Elephant) bool {
+        return (self.trunk != null);
+    }
     // ---------------------------------------------------
 
     pub fn visit(self: *Elephant) void {

@@ 65,10 65,10 @@ const std = @import("std");
 const Err = error{Cthulhu};
 
 pub fn main() void {
-    var first_line1: *const [16]u8 = ???;
+    var first_line1: *const [16]u8 = undefined;
     first_line1 = "That is not dead";
 
-    var first_line2: Err!*const [21]u8 = ???;
+    var first_line2: Err!*const [21]u8 = Err.Cthulhu;
     first_line2 = "which can eternal lie";
 
     std.debug.print("{s} {s} / ", .{ first_line1, first_line2 });


@@ 76,8 76,8 @@ pub fn main() void {
     printSecondLine();
 }
 
-fn printSecondLine() ??? {
-    var second_line2: ?*const [18]u8 = ???;
+fn printSecondLine() void {
+    var second_line2: ?*const [18]u8 = undefined;
     second_line2 = "even death may die";
 
     std.debug.print("And with strange aeons {s}.\n", .{second_line2.?});

@@ 87,7 87,7 @@ pub fn main() void {
     // Let's assign the std.debug.print function to a const named
     // "print" so that we can use this new name later!
 
-    const print = ???;
+    const print = std.debug.print;
 
     // Now let's look at assigning and pointing to values in Zig.
     //


@@ 152,13 152,13 @@ pub fn main() void {
     print("XP before:{}, ", .{glorp.experience});
 
     // Fix 1 of 2 goes here:
-    levelUp(glorp, reward_xp);
+    levelUp(glorp_access3, reward_xp);
 
     print("after:{}.\n", .{glorp.experience});
 }
 
 // Fix 2 of 2 goes here:
-fn levelUp(character_access: Character, xp: u32) void {
+fn levelUp(character_access: *Character, xp: u32) void {
     character_access.experience += xp;
 }
 

@@ 32,8 32,8 @@ 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[???];
+    const hand1: []u8 = cards[0..4];
+    const hand2: []u8 = cards[4..];
 
     std.debug.print("Hand1: ", .{});
     printHand(hand1);


@@ 43,7 43,7 @@ pub fn main() void {
 }
 
 // Please lend this function a hand. A u8 slice hand, that is.
-fn printHand(hand: ???) void {
+fn printHand(hand: []u8) void {
     for (hand) |h| {
         std.debug.print("{u} ", .{h});
     }

@@ 17,19 17,19 @@ const std = @import("std");
 pub fn main() void {
     const scrambled = "great base for all your justice are belong to us";
 
-    const base1: []u8 = scrambled[15..23];
-    const base2: []u8 = scrambled[6..10];
-    const base3: []u8 = scrambled[32..];
+    const base1: []const u8 = scrambled[15..23];
+    const base2: []const u8 = scrambled[6..10];
+    const base3: []const u8 = scrambled[32..];
     printPhrase(base1, base2, base3);
 
-    const justice1: []u8 = scrambled[11..14];
-    const justice2: []u8 = scrambled[0..5];
-    const justice3: []u8 = scrambled[24..31];
+    const justice1: []const u8 = scrambled[11..14];
+    const justice2: []const u8 = scrambled[0..5];
+    const justice3: []const u8 = scrambled[24..31];
     printPhrase(justice1, justice2, justice3);
 
     std.debug.print("\n", .{});
 }
 
-fn printPhrase(part1: []u8, part2: []u8, part3: []u8) void {
+fn printPhrase(part1: []const u8, part2: []const u8, part3: []const u8) void {
     std.debug.print("'{s} {s} {s}.' ", .{ part1, part2, part3 });
 }

@@ 32,7 32,7 @@ pub fn main() void {
     // we can CONVERT IT TO A SLICE. (Hint: we do know the length!)
     //
     // Please fix this line so the print statement below can print it:
-    const zen12_string: []const u8 = zen_manyptr;
+    const zen12_string: []const u8 = zen_manyptr[0..21];
 
     // Here's the moment of truth!
     std.debug.print("{s}\n", .{zen12_string});

@@ 59,8 59,8 @@ pub fn main() void {
     std.debug.print("Insect report! ", .{});
 
     // Oops! We've made a mistake here.
-    printInsect(ant, AntOrBee.c);
-    printInsect(bee, AntOrBee.c);
+    printInsect(ant, AntOrBee.a);
+    printInsect(bee, AntOrBee.b);
 
     std.debug.print("\n", .{});
 }

@@ 44,14 44,14 @@ pub fn main() void {
     std.debug.print("Insect report! ", .{});
 
     // Could it really be as simple as just passing the union?
-    printInsect(???);
-    printInsect(???);
+    printInsect(ant);
+    printInsect(bee);
 
     std.debug.print("\n", .{});
 }
 
 fn printInsect(insect: Insect) void {
-    switch (???) {
+    switch (insect) {
         .still_alive => |a| std.debug.print("Ant alive is: {}. ", .{a}),
         .flowers_visited => |f| std.debug.print("Bee visited {} flowers. ", .{f}),
     }

@@ 15,7 15,7 @@
 //
 const std = @import("std");
 
-const Insect = union(InsectStat) {
+const Insect = union(enum) {
     flowers_visited: u16,
     still_alive: bool,
 };

@@ 107,7 107,7 @@ const Path = struct {
 const a_paths = [_]Path{
     Path{
         .from = &a, // from: Archer's Point
-        .to = &b,   //   to: Bridge
+        .to = &b, //   to: Bridge
         .dist = 2,
     },
 };


@@ 115,12 115,12 @@ const a_paths = [_]Path{
 const b_paths = [_]Path{
     Path{
         .from = &b, // from: Bridge
-        .to = &a,   //   to: Archer's Point
+        .to = &a, //   to: Archer's Point
         .dist = 2,
     },
     Path{
         .from = &b, // from: Bridge
-        .to = &d,   //   to: Dogwood Grove
+        .to = &d, //   to: Dogwood Grove
         .dist = 1,
     },
 };


@@ 128,12 128,12 @@ const b_paths = [_]Path{
 const c_paths = [_]Path{
     Path{
         .from = &c, // from: Cottage
-        .to = &d,   //   to: Dogwood Grove
+        .to = &d, //   to: Dogwood Grove
         .dist = 3,
     },
     Path{
         .from = &c, // from: Cottage
-        .to = &e,   //   to: East Pond
+        .to = &e, //   to: East Pond
         .dist = 2,
     },
 };


@@ 141,17 141,17 @@ const c_paths = [_]Path{
 const d_paths = [_]Path{
     Path{
         .from = &d, // from: Dogwood Grove
-        .to = &b,   //   to: Bridge
+        .to = &b, //   to: Bridge
         .dist = 1,
     },
     Path{
         .from = &d, // from: Dogwood Grove
-        .to = &c,   //   to: Cottage
+        .to = &c, //   to: Cottage
         .dist = 3,
     },
     Path{
         .from = &d, // from: Dogwood Grove
-        .to = &f,   //   to: Fox Pond
+        .to = &f, //   to: Fox Pond
         .dist = 7,
     },
 };


@@ 159,20 159,20 @@ const d_paths = [_]Path{
 const e_paths = [_]Path{
     Path{
         .from = &e, // from: East Pond
-        .to = &c,   //   to: Cottage
+        .to = &c, //   to: Cottage
         .dist = 2,
     },
     Path{
         .from = &e, // from: East Pond
-        .to = &f,   //   to: Fox Pond
-        .dist = 1,  // (one-way down a short waterfall!)
+        .to = &f, //   to: Fox Pond
+        .dist = 1, // (one-way down a short waterfall!)
     },
 };
 
 const f_paths = [_]Path{
     Path{
         .from = &f, // from: Fox Pond
-        .to = &d,   //   to: Dogwood Grove
+        .to = &d, //   to: Dogwood Grove
         .dist = 7,
     },
 };


@@ 192,8 192,8 @@ const TripItem = union(enum) {
             // Oops! The hermit forgot how to capture the union values
             // in a switch statement. Please capture both values as
             // 'p' so the print statements work!
-            .place => print("{s}", .{p.name}),
-            .path => print("--{}->", .{p.dist}),
+            .place => |p| print("{s}", .{p.name}),
+            .path => |p| print("--{}->", .{p.dist}),
         }
     }
 };


@@ 255,7 255,7 @@ const HermitsNotebook = struct {
             // dereference and optional value "unwrapping" look
             // together. Remember that you return the address with the
             // "&" operator.
-            if (place == entry.*.?.place) return entry;
+            if (place == entry.*.?.place) return &entry.*.?;
             // Try to make your answer this long:__________;
         }
         return null;


@@ 309,7 309,7 @@ const HermitsNotebook = struct {
     //
     // Looks like the hermit forgot something in the return value of
     // this function. What could that be?
-    fn getTripTo(self: *HermitsNotebook, trip: []?TripItem, dest: *Place) void {
+    fn getTripTo(self: *HermitsNotebook, trip: []?TripItem, dest: *Place) !void {
         // We start at the destination entry.
         const destination_entry = self.getEntry(dest);
 


@@ 355,8 355,8 @@ pub fn main() void {
     // Here's where the hermit decides where he would like to go. Once
     // you get the program working, try some different Places on the
     // map!
-    const start = &a;        // Archer's Point
-    const destination = &f;  // Fox Pond
+    const start = &a; // Archer's Point
+    const destination = &f; // Fox Pond
 
     // Store each Path array as a slice in each Place. As mentioned
     // above, we needed to delay making these references to avoid

@@ 18,10 18,10 @@
 const print = @import("std").debug.print;
 
 pub fn main() void {
-    var zig = [_]u8 {
-        0o131,     // octal
-        0b1101000, // binary
-        0x66,      // hex
+    var zig = [_]u8{
+        0o132, // octal
+        0b1101001, // binary
+        0x67, // hex
     };
 
     print("{s} is cool.\n", .{zig});

@@ 40,7 40,7 @@ pub fn main() void {
     //
     // We'll convert this weight from tons to kilograms at a
     // conversion of 907.18kg to the ton.
-    var shuttle_weight: f16 = 907.18 * 2200;
+    var shuttle_weight: f32 = 907.18 * 2200.0;
 
     // By default, float values are formatted in scientific
     // notation. Try experimenting with '{d}' and '{d:.3}' to see

@@ 67,7 67,7 @@ const print = @import("std").debug.print;
 pub fn main() void {
     var letter: u8 = 'A';
 
-    const my_letter:   ???   = &letter;
+    const my_letter: ?*[1]u8 = &letter;
     //               ^^^^^^^
     //           Your type here.
     // Must coerce from &letter (which is a *u8).

@@ 47,7 47,7 @@ pub fn main() void {
     // return it from the for loop.
     const current_lang: ?[]const u8 = for (langs) |lang| {
         if (lang.len == 3) break lang;
-    };
+    } else null;
 
     if (current_lang) |cl| {
         print("Current language: {s}\n", .{cl});

@@ 129,7 129,7 @@ pub fn main() void {
         //
         // Please return this Food from the loop.
         break;
-    };
+    } else menu[menu.len - 1];
     // ^ Oops! We forgot to return Mac & Cheese as the default
     // Food when the requested ingredients aren't found.
 

@@ 69,6 69,6 @@ pub fn main() void {
     // Now it's your turn. See if you can fix this attempt to use
     // this builtin to reverse the bits of a u8 integer.
     const input: u8 = 0b11110000;
-    const tupni: u8 = @bitReverse(input);
+    const tupni: u8 = @bitReverse(u8, input);
     print("{b:0>8} backwards is {b:0>8}.\n", .{ input, tupni });
 }

@@ 40,7 40,7 @@
 // (Notice how the two functions which return types start with
 // uppercase letters? This is a standard naming practice in Zig.)
 //
-const print = import(std).debug.print; // Oops!
+const print = @import("std").debug.print; // Oops!
 
 const Narcissus = struct {
     me: *Narcissus = undefined,


@@ 57,18 57,17 @@ pub fn main() void {
 
     // Oops! We cannot leave the 'me' and 'myself' fields
     // undefined. Please set them here:
-    ??? = &narcissus;
-    ??? = &narcissus;
+    const me = &narcissus;
+    const myself = &narcissus;
 
     // This determines a "peer type" from three separate
     // references (they just happen to all be the same object).
-    const T1 = @TypeOf(narcissus, narcissus.me.*, narcissus.myself.*);
-
+    const T1 = @TypeOf(narcissus, me.*, myself.*);
     // Oh dear, we seem to have done something wrong when calling
     // this function. It is namespaced to the struct, but doesn't
     // use the method syntax (there's no self parameter). Please
     // fix this call:
-    const T2 = narcissus.fetchTheMostBeautifulType();
+    const T2 = Narcissus.fetchTheMostBeautifulType();
 
     print("A {} loves all {}es. ", .{ T1, T2 });
 


@@ 103,15 102,15 @@ pub fn main() void {
     // Please complete these 'if' statements so that the field
     // name will not be printed if the field is of type 'void'
     // (which is a zero-bit type that takes up no space at all!):
-    if (fields[0].??? != void) {
+    if (fields[0].field_type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[0].name});
     }
 
-    if (fields[1].??? != void) {
+    if (fields[1].field_type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[1].name});
     }
 
-    if (fields[2].??? != void) {
+    if (fields[2].field_type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[2].name});
     }
 

@@ 61,8 61,8 @@ pub fn main() void {
     // values. Therefore, it follows that we just specify numeric
     // types with specific sizes. The comptime numbers will be
     // coerced (if they'll fit!) into your chosen runtime types.
-    var var_int = 12345;
-    var var_float = 987.654;
+    var var_int: u32 = 12345;
+    var var_float: f32 = 987.654;
 
     // We can change what is stored at the areas set aside for
     // "var_int" and "var_float" in the running compiled program.

@@ 35,13 35,14 @@ pub fn main() void {
     // In this contrived example, we've decided to allocate some
     // arrays using a variable count! But something's missing...
     //
-    var count = 0;
+    comptime var count = 0;
 
     count += 1;
     var a1: [count]u8 = .{'A'} ** count;
 
     count += 1;
     var a2: [count]u8 = .{'B'} ** count;
+    //@compileLog("Count at compile time: ", count);
 
     count += 1;
     var a3: [count]u8 = .{'C'} ** count;


@@ 60,5 61,4 @@ pub fn main() void {
     //
     // Try uncommenting this line and playing around with it
     // (copy it, move it) to see what it does:
-    //@compileLog("Count at compile time: ", count);
 }

@@ 43,7 43,7 @@ const Schooner = struct {
         //
         // Please change this so that it sets a 0 scale to 1
         // instead.
-        if (my_scale == 0) @compileError("Scale 1:0 is not valid!");
+        if (my_scale == 0) my_scale = 1;
 
         self.scale = my_scale;
         self.hull_length /= my_scale;


@@ 69,7 69,7 @@ pub fn main() void {
     // Hey, we can't just pass this runtime variable as an
     // argument to the scaleMe() method. What would let us do
     // that?
-    var scale: u32 = undefined;
+    comptime var scale: u32 = undefined;
 
     scale = 32; // 1:32 scale
 

@@ 16,7 16,7 @@ const print = @import("std").debug.print;
 pub fn main() void {
     // Here we declare arrays of three different types and sizes
     // at compile time from a function call. Neat!
-    const s1 = makeSequence(u8, 3);  // creates a [3]u8
+    const s1 = makeSequence(u8, 3); // creates a [3]u8
     const s2 = makeSequence(u32, 5); // creates a [5]u32
     const s3 = makeSequence(i64, 7); // creates a [7]i64
 


@@ 42,8 42,8 @@ pub fn main() void {
 //     2) Sets the size of the array of type T (which is the
 //        sequence we're creating and returning).
 //
-fn makeSequence(comptime T: type, ??? size: usize) [???]T {
-    var sequence: [???]T = undefined;
+fn makeSequence(comptime T: type, comptime size: usize) [size]T {
+    var sequence: [size]T = undefined;
     var i: usize = 0;
 
     while (i < size) : (i += 1) {

@@ 123,8 123,8 @@ fn isADuck(possible_duck: anytype) bool {
     // Please make sure MyType has both waddle() and quack()
     // methods:
     const MyType = @TypeOf(possible_duck);
-    const walks_like_duck = ???;
-    const quacks_like_duck = ???;
+    const walks_like_duck = @hasDecl(MyType, "waddle");
+    const quacks_like_duck = @hasDecl(MyType, "quack");
 
     const is_duck = walks_like_duck and quacks_like_duck;
 

@@ 40,7 40,7 @@ pub fn main() void {
 
     const fields = @typeInfo(Narcissus).Struct.fields;
 
-    ??? {
+    inline for (fields) |field| {
         if (field.field_type != void) {
             print(" {s}", .{field.name});
         }

@@ 35,7 35,7 @@ pub fn main() void {
     // at compile time.
     //
     // Please fix this to loop once per "instruction":
-    ??? (i < instructions.len) : (???) {
+    inline while (i < instructions.len) : (i += 3) {
 
         // This gets the digit from the "instruction". Can you
         // figure out why we subtract '0' from it?

@@ 32,12 32,12 @@ const llamas = [llama_count]u32{ 5, 10, 15, 20, 25 };
 pub fn main() void {
     // We meant to fetch the last llama. Please fix this simple
     // mistake so the assertion no longer fails.
-    const my_llama = getLlama(5);
+    const my_llama = comptime getLlama(5);
 
     print("My llama value is {}.\n", .{my_llama});
 }
 
-fn getLlama(i: usize) u32 {
+fn getLlama(comptime i: usize) u32 {
     // We've put a guard assert() at the top of this function to
     // prevent mistakes. The 'comptime' keyword here means that
     // the mistake will be caught when we compile!


@@ 50,15 50,15 @@ fn getLlama(i: usize) u32 {
     // because the 'i' parameter needs to be guaranteed to be
     // known at compile time. What can you do with the 'i'
     // parameter above to make this so?
-    comptime assert(i < llama_count);
+    assert(i < llama_count);
 
-    return llamas[i];
+    return llamas[i - 1];
 }
 
 // Fun fact: this assert() function is identical to
 // std.debug.assert() from the Zig Standard Library.
 fn assert(ok: bool) void {
-    if (!ok) unreachable;
+    if (ok) unreachable;
 }
 //
 // Bonus fun fact: I accidentally replaced all instances of 'foo'

@@ 39,7 39,7 @@ const llamas = makeLlamas(llama_count);
 
 // And here's the function. Note that the return value type
 // depends on one of the input arguments!
-fn makeLlamas(count: usize) [count]u8 {
+fn makeLlamas(comptime count: usize) [count]u8 {
     var temp: [count]u8 = undefined;
     var i = 0;
 

@@ 48,8 48,8 @@ const Path = struct {
 // instead.
 //
 // Please fill in the body of this function!
-fn makePath(from: *Place, to: *Place, dist: u8) Path {
-
+fn makePath(comptime from: *Place, comptime to: *Place, comptime dist: u8) Path {
+    return Path{ .from = from, .to = to, .dist = dist };
 }
 
 // Using our new function, these path definitions take up considerably less


@@ 151,8 151,8 @@ const HermitsNotebook = struct {
 };
 
 pub fn main() void {
-    const start = &a;        // Archer's Point
-    const destination = &f;  // Fox Pond
+    const start = &a; // Archer's Point
+    const destination = &f; // Fox Pond
 
     // TODO: can we neaten this up????
     a.paths = a_paths[0..];

@@ 81,7 81,7 @@ fn printSequence(my_seq: anytype) void {
             print("Array:", .{});
 
             // Loop through the items in my_seq.
-            for (???) |s| {
+            for (my_seq) |s| {
                 print("{}", .{s});
             }
         },


@@ 93,7 93,7 @@ fn printSequence(my_seq: anytype) void {
             // Loop through the items in my_seq until we hit the
             // sentinel value.
             var i: usize = 0;
-            while (??? != my_sentinel) {
+            while (my_seq[i] != my_sentinel) {
                 print("{}", .{my_seq[i]});
                 i += 1;
             }

@@ 60,7 60,7 @@ pub fn main() void {
     // length... You've actually solved this problem before!
     //
     // Here's a big hint: do you remember how to take a slice?
-    const printable = ???;
+    const printable = foo.data[0..foo.length];
 
     print("{s}\n", .{printable});
 }

@@ 21,7 21,7 @@ pub fn main() void {
     const data: [*]const u8 = "Weird Data!";
 
     // Please cast 'data' to 'printable':
-    const printable: [*:0]const u8 = ???;
+    const printable: [*:0]const u8 = @ptrCast([*:0]const u8, data);
 
     print("{s}\n", .{printable});
 }

@@ 20,11 20,11 @@
 const print = @import("std").debug.print;
 
 pub fn main() void {
-    const 55_cows: i32 = 55;
-    const isn't true: bool = false;
-    
+    const @"55_cows": i32 = 55;
+    const @"isn't true": bool = false;
+
     print("Sweet freedom: {}, {}.\n", .{
-        55_cows,
-        isn't true,
+        @"55_cows",
+        @"isn't true",
     });
 }

@@ 48,13 48,13 @@ pub fn main() void {
     // * circle1 should hold i32 integers
     // * circle2 should hold f32 floats
     //
-    var circle1 = ??? {
+    var circle1 = Circle(i32){
         .center_x = 25,
         .center_y = 70,
         .radius = 15,
     };
 
-    var circle2 = ??? {
+    var circle2 = Circle(f32){
         .center_x = 25.234,
         .center_y = 70.999,
         .radius = 15.714,

@@ 38,7 38,7 @@ pub fn main() void {
 
 // Please complete this function which prints an anonymous struct
 // representing a circle.
-fn printCircle(???) void {
+fn printCircle(circle: anytype) void {
     print("x:{} y:{} radius:{}\n", .{
         circle.center_x,
         circle.center_y,

@@ 82,14 82,14 @@ fn printTuple(tuple: anytype) void {
     //         @typeInfo(Circle).Struct.fields
     //
     // This will be an array of StructFields.
-    const fields = ???;
+    const fields = @typeInfo(@TypeOf(tuple)).Struct.fields;
 
     // 2. Loop through each field. This must be done at compile
     // time.
     //
     //     Hint: remember 'inline' loops?
     //
-    for (fields) |field| {
+    inline for (fields) |field| {
         // 3. Print the field's name, type, and value.
         //
         //     Each 'field' in this loop is one of these:


@@ 117,9 117,9 @@ fn printTuple(tuple: anytype) void {
         //
         // The first field should print as: "0"(bool):true
         print("\"{s}\"({s}):{any} ", .{
-            field.???,
-            field.???,
-            ???,
+            field.name,
+            field.field_type,
+            field.default_value,
         });
     }
 }

@@ 20,6 20,6 @@ pub fn main() void {
     //
     //     = .{'h', 'e', 'l', 'l', 'o'};
     //
-    const hello = .{'h', 'e', 'l', 'l', 'o'};
+    const hello: [5]u8 = .{ 'h', 'e', 'l', 'l', 'o' };
     print("I say {s}!\n", .{hello});
 }

@@ 48,7 48,7 @@ const print = @import("std").debug.print;
 pub fn main() void {
     // Additional Hint: you can assign things to '_' when you
     // don't intend to do anything with them.
-    foo();
+    _ = async foo();
 }
 
 fn foo() void {

@@ 19,6 19,7 @@ const print = @import("std").debug.print;
 
 pub fn main() void {
     var foo_frame = async foo();
+    resume foo_frame;
 }
 
 fn foo() void {

@@ 13,7 13,10 @@ pub fn main() void {
     const n = 5;
     var foo_frame = async foo(n);
 
-    ???
+    resume foo_frame;
+    resume foo_frame;
+    resume foo_frame;
+    resume foo_frame;
 
     print("\n", .{});
 }

@@ 16,7 16,7 @@ pub fn main() void {
 
     while (global_counter <= 5) {
         print("{} ", .{global_counter});
-        ???
+        resume foo_frame;
     }
 
     print("\n", .{});


@@ 24,7 24,7 @@ pub fn main() void {
 
 fn foo() void {
     while (true) {
-        ???
-        ???
+        global_counter += 1;
+        suspend {}
     }
 }

@@ 36,7 36,7 @@ const print = @import("std").debug.print;
 pub fn main() void {
     var myframe = async getPageTitle("http://example.com");
 
-    var value = ???
+    var value = await myframe;
 
     print("{s}\n", .{value});
 }

@@ 41,8 41,8 @@ pub fn main() void {
     var com_frame = async getPageTitle("http://example.com");
     var org_frame = async getPageTitle("http://example.org");
 
-    var com_title = com_frame;
-    var org_title = org_frame;
+    var com_title = await com_frame;
+    var org_title = await org_frame;
 
     print(".com: {s}, .org: {s}.\n", .{ com_title, org_title });
 }

@@ 29,7 29,7 @@ pub fn main() void {
     // The main() function can not be async. But we know
     // getBeef() will not suspend with this particular
     // invocation. Please make this okay:
-    var my_beef = getBeef(0);
+    var my_beef = nosuspend getBeef(0);
 
     print("beef? {X}!\n", .{my_beef});
 }

@@ 17,7 17,7 @@ pub fn main() void {
 
     var frame = async suspendable();
 
-    print("X", .{});
+    print("D", .{});
 
     resume frame;
 


@@ 25,11 25,11 @@ pub fn main() void {
 }
 
 fn suspendable() void {
-    print("X", .{});
+    print("B", .{});
 
     suspend {
-        print("X", .{});
+        print("C", .{});
     }
 
-    print("X", .{});
+    print("E", .{});
 }