61-72

exercises/061_coercions.zig

@@ -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).

exercises/062_loop_expressions.zig

@@ -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});

exercises/063_labels.zig

@@ -128,8 +128,8 @@ pub fn main() void {
         // wanted for this Food.
         //
         // Please return this Food from the loop.
-        break;
-    };
+        break food;
+    } else menu[0];
     // ^ Oops! We forgot to return Mac & Cheese as the default
     // Food when the requested ingredients aren't found.
 

exercises/064_builtins.zig

@@ -63,7 +63,7 @@ pub fn main() void {
     //
     // If there was no overflow at all while adding 5 to a, what value would
     // 'my_result' hold? Write the answer in into 'expected_result'.
-    const expected_result: u8 = ???;
+    const expected_result: u8 = 18;
     print(". Without overflow: {b:0>8}. ", .{expected_result});
 
     print("Furthermore, ", .{});
@@ -78,6 +78,6 @@ 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, tupni);
+    const tupni: u8 = @bitReverse(input);
     print("{b:0>8} backwards is {b:0>8}.\n", .{ input, tupni });
 }

exercises/065_builtins2.zig

@@ -58,7 +58,7 @@ pub fn main() void {
     // Oops! We cannot leave the 'me' and 'myself' fields
     // undefined. Please set them here:
     narcissus.me = &narcissus;
-    narcissus.??? = ???;
+    narcissus.myself = &narcissus;
 
     // This determines a "peer type" from three separate
     // references (they just happen to all be the same object).
@@ -70,7 +70,7 @@ pub fn main() void {
     //
     // The fix for this is very subtle, but it makes a big
     // difference!
-    const Type2 = narcissus.fetchTheMostBeautifulType();
+    const Type2 = Narcissus.fetchTheMostBeautifulType();
 
     // Now we print a pithy statement about Narcissus.
     print("A {s} loves all {s}es. ", .{
@@ -109,15 +109,15 @@ 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].type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[0].name});
     }
 
-    if (fields[1].??? != void) {
+    if (fields[1].type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[1].name});
     }
 
-    if (fields[2].??? != void) {
+    if (fields[2].type != void) {
         print(" {s}", .{@typeInfo(Narcissus).Struct.fields[2].name});
     }
 

exercises/066_comptime.zig

@@ -62,8 +62,8 @@ pub fn main() void {
     // types with specific sizes. The comptime numbers will be
     // coerced (if they'll fit!) into your chosen runtime types.
     // For this it is necessary to specify a size, e.g. 32 bit.
-    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.

exercises/067_comptime2.zig

@@ -35,7 +35,7 @@ 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;
     const a1: [count]u8 = .{'A'} ** count;
@@ -60,5 +60,5 @@ 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);
+    //    @compileLog("Count at compile time: ", count);
 }

exercises/068_comptime3.zig

@@ -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
 

exercises/069_comptime4.zig

@@ -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) {

exercises/070_comptime5.zig

@@ -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;
 

exercises/071_comptime6.zig

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

exercises/072_comptime7.zig

@@ -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?