5 Commits

6 changed files with 69 additions and 84 deletions

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@@ -93,36 +93,25 @@ pub fn main() void {
print("He has room in his heart for:", .{}); print("He has room in his heart for:", .{});
// A StructFields array // `field_names` is a slice of strings and it holds the names of the struct's fields
const fields = @typeInfo(Narcissus).@"struct".fields; // `field_types` is a slice of strings and it holds the types of the struct's fields,
// it is guaranteed to be the same length as `field_names`
const field_names = @typeInfo(Narcissus).@"struct".field_names;
const field_types = @typeInfo(Narcissus).@"struct".field_types;
// 'fields' is a slice of StructFields. Here's the declaration:
//
// pub const StructField = struct {
// name: [:0]const u8, // Don't worry about `:0` yet!
// type: type,
// default_value_ptr: ?*const anyopaque,
// is_comptime: bool,
// alignment: comptime_int,
//
// defaultValue() ?sf.type // Function that loads the
// // field's default value from
// // `default_value_ptr`
// };
//
// Please complete these 'if' statements so that the field // Please complete these 'if' statements so that the field
// name will not be printed if the field is of type 'void' // 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!): // (which is a zero-bit type that takes up no space at all!):
if (fields[0].??? != void) { if (field_???[???] != void) {
print(" {s}", .{fields[0].name}); print(" {s}", .{field_???[???]});
} }
if (fields[1].??? != void) { if (field_???[???] != void) {
print(" {s}", .{fields[1].name}); print(" {s}", .{field_???[???]});
} }
if (fields[2].??? != void) { if (field_???[???] != void) {
print(" {s}", .{fields[2].name}); print(" {s}", .{field_???[???]});
} }
// Yuck, look at all that repeated code above! I don't know // Yuck, look at all that repeated code above! I don't know

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@@ -36,13 +36,14 @@ pub fn main() void {
// statement was repeated three times almost verbatim. Yuck! // statement was repeated three times almost verbatim. Yuck!
// //
// Please use an 'inline for' to implement the block below // Please use an 'inline for' to implement the block below
// for each field in the slice 'fields'! // for each field in the corresponding slices (they're of the same length)!
const fields = @typeInfo(Narcissus).@"struct".fields; const field_names = @typeInfo(Narcissus).@"struct".field_names;
const field_types = @typeInfo(Narcissus).@"struct".field_types;
??? { ??? {
if (field.type != void) { if (field_type != void) {
print(" {s}", .{field.name}); print(" {s}", .{field_name});
} }
} }

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@@ -74,36 +74,27 @@ fn printTuple(tuple: anytype) void {
// @typeInfo() - takes a type, returns a TypeInfo union // @typeInfo() - takes a type, returns a TypeInfo union
// with fields specific to that type. // with fields specific to that type.
// //
// The list of a struct type's fields can be found in // The list of a struct type's field types can be found in
// TypeInfo's @"struct".fields. // TypeInfo's @"struct".field_types.
// //
// Example: // Example:
// //
// @typeInfo(Circle).@"struct".fields // @typeInfo(Circle).@"struct".field_types
// //
// This will be an array of StructFields. // This will be an array of field types.
const fields = ???; const field_types = ???;
// This will be an array of field names.
const field_names = ???;
// 2. Loop through each field. This must be done at compile // 2. Loop through each field. This must be done at compile
// time. // time.
// //
// Hint: remember 'inline' loops? // Hint: remember 'inline' loops?
// //
for (fields) |field| { for (???, ???) |???, ???| {
// 3. Print the field's name, type, and value. // 3. Print the field's name, type, and value.
// //
// Each 'field' in this loop is one of these:
//
// pub const StructField = struct {
// name: [:0]const u8,
// type: type,
// default_value_ptr: ?*const anyopaque,
// is_comptime: bool,
// alignment: comptime_int,
// };
//
// Note we will learn about 'anyopaque' type later
//
// You'll need this builtin: // You'll need this builtin:
// //
// @field(lhs: anytype, comptime field_name: []const u8) // @field(lhs: anytype, comptime field_name: []const u8)
@@ -123,8 +114,8 @@ fn printTuple(tuple: anytype) void {
// for declarations. If it's a value, it looks for data. // for declarations. If it's a value, it looks for data.
// //
print("\"{s}\"({any}):{any} ", .{ print("\"{s}\"({any}):{any} ", .{
field.???, field_name,
field.???, field_type,
???, ???,
}); });
} }

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@@ -1,5 +1,5 @@
--- exercises/065_builtins2.zig 2026-02-27 13:10:36 --- exercises/065_builtins2.zig 2026-06-01 15:33:16.617432671 +0200
+++ answers/065_builtins2.zig 2026-02-27 13:10:52 +++ answers/065_builtins2.zig 2026-06-01 15:33:31.104018108 +0200
@@ -58,7 +58,7 @@ @@ -58,7 +58,7 @@
// Oops! We cannot leave the 'me' and 'myself' fields // Oops! We cannot leave the 'me' and 'myself' fields
// undefined. Please set them here: // undefined. Please set them here:
@@ -18,22 +18,26 @@
// Now we print a pithy statement about Narcissus. // Now we print a pithy statement about Narcissus.
print("A {s} loves all {s}es. ", .{ print("A {s} loves all {s}es. ", .{
@@ -113,15 +113,15 @@ @@ -102,16 +102,16 @@
// Please complete these 'if' statements so that the field // Please complete these 'if' statements so that the field
// name will not be printed if the field is of type 'void' // 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!): // (which is a zero-bit type that takes up no space at all!):
- if (fields[0].??? != void) { - if (field_???[???] != void) {
+ if (fields[0].type != void) { - print(" {s}", .{field_???[???]});
print(" {s}", .{fields[0].name}); + if (field_types[0] != void) {
+ print(" {s}", .{field_names[0]});
} }
- if (fields[1].??? != void) { - if (field_???[???] != void) {
+ if (fields[1].type != void) { - print(" {s}", .{field_???[???]});
print(" {s}", .{fields[1].name}); + if (field_types[1] != void) {
+ print(" {s}", .{field_names[1]});
} }
- if (fields[2].??? != void) { - if (field_???[???] != void) {
+ if (fields[2].type != void) { - print(" {s}", .{field_???[???]});
print(" {s}", .{fields[2].name}); + if (field_types[2] != void) {
+ print(" {s}", .{field_names[2]});
} }
// Yuck, look at all that repeated code above! I don't know

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@@ -1,11 +1,11 @@
--- exercises/071_comptime6.zig 2024-09-02 19:21:50.250454978 +0200 --- exercises/071_comptime6.zig 2026-06-01 15:35:27.223400223 +0200
+++ answers/071_comptime6.zig 2024-09-02 19:21:23.553250563 +0200 +++ answers/071_comptime6.zig 2026-06-01 15:36:35.349728561 +0200
@@ -40,7 +40,7 @@ @@ -41,7 +41,7 @@
const field_names = @typeInfo(Narcissus).@"struct".field_names;
const fields = @typeInfo(Narcissus).@"struct".fields; const field_types = @typeInfo(Narcissus).@"struct".field_types;
- ??? { - ??? {
+ inline for (fields) |field| { + inline for (field_names, field_types) |field_name, field_type| {
if (field.type != void) { if (field_type != void) {
print(" {s}", .{field.name}); print(" {s}", .{field_name});
} }

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@@ -1,32 +1,32 @@
--- exercises/082_anonymous_structs3.zig 2026-02-27 13:05:46 --- exercises/082_anonymous_structs3.zig 2026-06-01 15:59:11.872467805 +0200
+++ answers/082_anonymous_structs3.zig 2026-02-27 13:07:22 +++ answers/082_anonymous_structs3.zig 2026-06-01 15:58:38.004730144 +0200
@@ -82,14 +82,14 @@ @@ -82,17 +82,17 @@
// @typeInfo(Circle).@"struct".fields // @typeInfo(Circle).@"struct".field_types
// //
// This will be an array of StructFields. // This will be an array of field types.
- const fields = ???; - const field_types = ???;
+ const fields = @typeInfo(@TypeOf(tuple)).@"struct".fields; + const field_types = @typeInfo(@TypeOf(tuple)).@"struct".field_types;
// This will be an array of field names.
- const field_names = ???;
+ const field_names = @typeInfo(@TypeOf(tuple)).@"struct".field_names;
// 2. Loop through each field. This must be done at compile // 2. Loop through each field. This must be done at compile
// time. // time.
// //
// Hint: remember 'inline' loops? // Hint: remember 'inline' loops?
// //
- for (fields) |field| { - for (???, ???) |???, ???| {
+ inline for (fields) |field| { + inline for (field_types, field_names) |field_type, field_name| {
// 3. Print the field's name, type, and value. // 3. Print the field's name, type, and value.
// //
// Each 'field' in this loop is one of these: // You'll need this builtin:
@@ -123,9 +123,9 @@ @@ -116,7 +116,7 @@
// for declarations. If it's a value, it looks for data.
//
print("\"{s}\"({any}):{any} ", .{ print("\"{s}\"({any}):{any} ", .{
- field.???, field_name,
- field.???, field_type,
- ???, - ???,
+ field.name, + @field(tuple, field_name),
+ field.type,
+ @field(tuple, field.name),
}); });
} }
} }