106-107 completed

exercises/099_formatting.zig

@@ -131,7 +131,7 @@ pub fn main() !void {
         for (0..size) |b| {
             // What formatting is needed here to make our columns
             // nice and straight?
-            print("{???} ", .{(a + 1) * (b + 1)});
+            print("{d:>3} ", .{(a + 1) * (b + 1)});
         }
 
         // After each row we use double line feed:

exercises/100_for4.zig

@@ -39,7 +39,7 @@ pub fn main() void {
     const hex_nums = [_]u8{ 0xb, 0x2a, 0x77 };
     const dec_nums = [_]u8{ 11, 42, 119 };
 
-    for (hex_nums, ???) |hn, ???| {
+    for (hex_nums, dec_nums) |hn, dn| {
         if (hn != dn) {
             std.debug.print("Uh oh! Found a mismatch: {d} vs {d}\n", .{ hn, dn });
             return;

exercises/101_for5.zig

@@ -51,7 +51,7 @@ pub fn main() void {
 
     // We would like to number our list starting with 1, not 0.
     // How do we do that?
-    for (roles, gold, experience, ???) |c, g, e, i| {
+    for (roles, gold, experience, 1..) |c, g, e, i| {
         const role_name = switch (c) {
             .wizard => "Wizard",
             .thief => "Thief",

exercises/102_testing.zig

@@ -83,7 +83,7 @@ fn sub(a: f16, b: f16) f16 {
 // an error that you need
 // to correct.
 test "sub" {
-    try testing.expect(sub(10, 5) == 6);
+    try testing.expect(sub(10, 5) == 5);
 
     try testing.expect(sub(3, 1.5) == 1.5);
 }
@@ -108,5 +108,5 @@ test "divide" {
     // Now we test if the function returns an error
     // if we pass a zero as denominator.
     // But which error needs to be tested?
-    try testing.expectError(error.???, divide(15, 0));
+    try testing.expectError(error.DivisionByZero, divide(15, 0));
 }

exercises/103_tokenization.zig

@@ -119,9 +119,9 @@
 // after all we need some practice. Suppose we want to count the words
 // of this little poem:
 //
-// 	My name is Ozymandias, King of Kings;
+//  My name is Ozymandias, King of Kings;
-// 	Look on my Works, ye Mighty, and despair!
+//  Look on my Works, ye Mighty, and despair!
-// 	 by Percy Bysshe Shelley
+//   by Percy Bysshe Shelley
 //
 //
 const std = @import("std");
@@ -136,7 +136,7 @@ pub fn main() !void {
     ;
 
     // now the tokenizer, but what do we need here?
-    var it = std.mem.tokenizeAny(u8, poem, ???);
+    var it = std.mem.tokenizeAny(u8, poem, " ,;!\n");
 
     // print all words and count them
     var cnt: usize = 0;

exercises/104_threading.zig

@@ -97,12 +97,12 @@ pub fn main() !void {
         defer handle.join();
 
         // Second thread
-        const handle2 = try std.Thread.spawn(.{}, thread_function, .{-4}); // that can't be right?
+        const handle2 = try std.Thread.spawn(.{}, thread_function, .{2}); // that can't be right?
         defer handle2.join();
 
         // Third thread
         const handle3 = try std.Thread.spawn(.{}, thread_function, .{3});
-        defer ??? // <-- something is missing
+        defer handle3.join(); // <-- something is missing
 
         // After the threads have been started,
         // they run in parallel and we can still do some work in between.

exercises/105_threading2.zig

@@ -81,8 +81,8 @@ pub fn main() !void {
         defer handle1.join();
 
         // Second thread to calculate the minus numbers.
-        ???
+        const handle2 = try std.Thread.spawn(.{}, thread_pi, .{ &pi_minus, 3, count });
-        
+        defer handle2.join();
     }
     // Here we add up the results.
     std.debug.print("PI ≈ {d:.8}\n", .{4 + pi_plus - pi_minus});

exercises/106_files.zig

@@ -35,7 +35,7 @@ pub fn main() !void {
         // by doing nothing
         //
         // we want to catch error.PathAlreadyExists and do nothing
-        ??? => {},
+        error.PathAlreadyExists => {},
         // if there's any other unexpected error we just propagate it through
         else => return e,
     };
@@ -44,7 +44,7 @@ pub fn main() !void {
     // wait a minute...
     // opening a directory might fail!
     // what should we do here?
-    var output_dir: std.fs.Dir = cwd.openDir("output", .{});
+    var output_dir: std.fs.Dir = try cwd.openDir("output", .{});
     defer output_dir.close();
 
     // we try to open the file `zigling.txt`,
@@ -55,7 +55,7 @@ pub fn main() !void {
     // but here we are not yet done writing to the file
     // if only there were a keyword in Zig that
     // allowed you to "defer" code execution to the end of the scope...
-    file.close();
+    defer file.close();
 
     // you are not allowed to move these two lines above the file closing line!
     const byte_written = try file.write("It's zigling time!");

exercises/107_files2.zig

@@ -33,7 +33,7 @@ pub fn main() !void {
     // initalize an array of u8 with all letter 'A'
     // we need to pick the size of the array, 64 seems like a good number
     // fix the initalization below
-    var content = ['A']*64;
+    var content = [_]u8{'A'} ** 64;
     // this should print out : `AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA`
     std.debug.print("{s}\n", .{content});
 
@@ -41,12 +41,12 @@ pub fn main() !void {
     // can you go here to find a way to read the content?
     // https://ziglang.org/documentation/master/std/#std.fs.File
     // hint: you might find two answers that are both vaild in this case
-    const bytes_read = zig_read_the_file_or_i_will_fight_you(&content);
+    const bytes_read = try file.readAll(&content);
 
     // Woah, too screamy. I know you're excited for zigling time but tone it down a bit.
     // Can you print only what we read from the file?
     std.debug.print("Successfully Read {d} bytes: {s}\n", .{
         bytes_read,
-        content, // change this line only
+        content[0..bytes_read], // change this line only
     });
 }