Merge branch 'main' of https://codeberg.org/ziglings/exercises

Reviewed-on: https://codeberg.org/ziglings/exercises/pulls/79

.gitignore

@@ -3,3 +3,5 @@
 /answers/
 /patches/healed/
 *.md
+/output/
+

build.zig

@@ -15,7 +15,7 @@ const print = std.debug.print;
 //     1) Getting Started
 //     2) Version Changes
 comptime {
-    const required_zig = "0.12.0-dev.3397";
+    const required_zig = "0.12.0-dev.3518";
     const current_zig = builtin.zig_version;
     const min_zig = std.SemanticVersion.parse(required_zig) catch unreachable;
     if (current_zig.order(min_zig) == .lt) {
@@ -247,7 +247,7 @@ const ZiglingStep = struct {
     fn make(step: *Step, prog_node: *std.Progress.Node) !void {
         // NOTE: Using exit code 2 will prevent the Zig compiler to print the message:
         // "error: the following build command failed with exit code 1:..."
-        const self = @fieldParentPtr(ZiglingStep, "step", step);
+        const self: *ZiglingStep = @alignCast(@fieldParentPtr("step", step));
 
         if (self.exercise.skip) {
             print("Skipping {s}\n\n", .{self.exercise.main_file});
@@ -495,8 +495,7 @@ const PrintStep = struct {
     }
 
     fn make(step: *Step, _: *std.Progress.Node) !void {
-        const self = @fieldParentPtr(PrintStep, "step", step);
+        const self: *PrintStep = @alignCast(@fieldParentPtr("step", step));
-
         print("{s}", .{self.message});
     }
 };
@@ -1121,6 +1120,17 @@ const exercises = [_]Exercise{
         .main_file = "105_threading2.zig",
         .output = "PI ≈ 3.14159265",
     },
+    .{
+        .main_file = "106_files.zig",
+        .output = "Successfully wrote 18 bytes.",
+    },
+    .{
+        .main_file = "107_files2.zig",
+        .output =
+        \\AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+        \\Successfully Read 18 byte: It's zigling time!
+        ,
+    },
     .{
         .main_file = "999_the_end.zig",
         .output =

exercises/104_threading.zig

@@ -106,7 +106,7 @@ pub fn main() !void {
 
         // After the threads have been started,
         // they run in parallel and we can still do some work in between.
-        std.time.sleep((1) * std.time.ns_per_s);
+        std.time.sleep(1500 * std.time.ns_per_ms);
         std.debug.print("Some weird stuff, after starting the threads.\n", .{});
     }
     // After we have left the closed area, we wait until
@@ -117,8 +117,13 @@ pub fn main() !void {
 // This function is started with every thread that we set up.
 // In our example, we pass the number of the thread as a parameter.
 fn thread_function(num: usize) !void {
+    std.time.sleep(200 * num * std.time.ns_per_ms);
     std.debug.print("thread {d}: {s}\n", .{ num, "started." });
-    std.time.sleep((5 - num % 3) * std.time.ns_per_s);
+
+    // This timer simulates the work of the thread.
+    const work_time = 3 * ((5 - num % 3) - 2);
+    std.time.sleep(work_time * std.time.ns_per_s);
+
     std.debug.print("thread {d}: {s}\n", .{ num, "finished." });
 }
 // This is the easiest way to run threads in parallel.

exercises/105_threading2.zig

@@ -46,7 +46,7 @@
 // 1,000,000,000 partial values. And for each additional digit we have to
 // add a zero.
 // Even fast computers - and I mean really fast computers - get a bit warmer
-// on the CPU when it comes to really many diggits. But the 8 digits are
+// on the CPU when it comes to really many digits. But the 8 digits are
 // enough for us for now, because we want to understand the principle and
 // nothing more, right?
 //

exercises/106_files.zig

@@ -0,0 +1,92 @@
+//
+// Until now, we've only been printing our output in the console,
+// which is good enough for fighting alien and hermit bookkeeping.
+//
+// However, many other task require some interaction with the file system,
+// which is the underlying structure for organizing files on your computer.
+//
+// The File System provide a hierarchical structure for storing files
+// by organizing files into directories, which hold files and other directories,
+// thus creating a tree structure for navigating.
+//
+// Fortunately, zig standard library provide a simple api for interacting
+// with the file system, see the detail documentation here
+//
+// https://ziglang.org/documentation/master/std/#std.fs
+//
+// In this exercise, we'll try to
+//   - create a new directory
+//   - open a file in the directory
+//   - write to the file.
+//
+// import std as always
+const std = @import("std");
+
+pub fn main() !void {
+    // first we get the current working directory
+    const cwd: std.fs.Dir = std.fs.cwd();
+
+    // then we'll try to make a new directory /output/
+    // to put our output files.
+    cwd.makeDir("output") catch |e| switch (e) {
+        // there are chance you might want to run this
+        // program more than once and the path might already
+        // been created, so we'll have to handle this error
+        // by doing nothing
+        //
+        // we want to catch error.PathAlreadyExists and do nothing
+        ??? => {},
+        // if is any other unexpected error we just propagate it through
+        else => return e,
+    };
+
+    // then we'll try to open our freshly created directory
+    // wait a minute
+    // opening a directory might fail!
+    // what should we do here?
+    var output_dir: std.fs.Dir = cwd.openDir("output", .{});
+    defer output_dir.close();
+
+    // we try to open the file `zigling.txt`,
+    // and propagate the error up if there are any errors
+    const file: std.fs.File = try output_dir.createFile("zigling.txt", .{});
+    // it is a good habit to close a file after you are done with
+    // so that other program can read it and prevent data corruption
+    // but here we are not yet done writing to the file
+    // if only there are a keyword in zig that
+    // allow you "defer" code execute to the end of scope...
+    file.close();
+
+    // !you are not allow to switch this two lines to before file closing line!
+    const byte_written = try file.write("It's zigling time!");
+    std.debug.print("Successfully wrote {d} bytes.\n", .{byte_written});
+}
+// to check if you actually write to the file, you can either,
+// 1. open the file on your text editor, or
+// 2. print the content of the file in the console with command
+//    >> cat ./output/zigling.txt
+//
+//
+// More on Creating files
+//
+// notice in:
+// ... try output_dir.createFile("zigling.txt", .{});
+//                                              ^^^
+//                 we passed this anonymous struct to the function call
+//
+// this is the struct `CreateFlag` with default fields
+// {
+//      read: bool = false,
+//      truncate: bool = true,
+//      exclusive: bool = false,
+//      lock: Lock = .none,
+//      lock_nonblocking: bool = false,
+//      mode: Mode = default_mode
+// }
+//
+// Question:
+//   - what should you do if you want to also read the file after opening it?
+//   - go to documentation of the struct `std.fs.Dir` here
+//     https://ziglang.org/documentation/master/std/#std.fs.Dir
+//       - can you find a function for opening a file? how about deleting a file?
+//       - what kind of option can you uses with those function?

exercises/107_files2.zig

@@ -0,0 +1,52 @@
+//
+// Prerequisite :
+//    - exercise/106_files.zig, or
+//    - create a file {project_root}/output/zigling.txt
+//      with content `It's zigling time!`(18 byte total)
+//
+// Now there no point in writing to a file if we don't read from it am I right?
+// let's wrote a program to read the content of the file that we just created.
+//
+// I am assuming you've created the appropriate files for this to work.
+//
+// Alright, bud, lean in close here's the game plan.
+//    - First, we open the {project_root}/output/ directory
+//    - Secondly, we open file `zigling.txt` in that directory
+//    - then, we initalize an array of character with all letter 'A', and print it
+//    - Afte that, we read the content of the file to the array
+//    - Finally, we print out the read content
+
+const std = @import("std");
+
+pub fn main() !void {
+    // Get the current working directory
+    const cwd = std.fs.cwd();
+
+    // try to open ./output assuming you did your 106_files exercise
+    var output_dir = try cwd.openDir("output", .{});
+    defer output_dir.close();
+
+    // try to open the file
+    const file = try output_dir.openFile("zigling.txt", .{});
+    defer file.close();
+
+    // initalize an array of u8 with all letter 'A'.
+    // we need to pick a size of the array, 64 seems like a good number.
+    // fix the initalization below
+    var content = ['A']*64;
+    // this should print out : `AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA`
+    std.debug.print("{s}\n", .{content});
+
+    // okay, seem like threat of violence is not the answer in this case
+    // 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 answer that are both vaild in this case
+    const byte_read = zig_read_the_file_or_i_will_fight_you(&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} byte: {s}\n", .{
+        byte_read,
+        content, // change this line only
+    });
+}

patches/patches/104_threading.patch

@@ -1,5 +1,5 @@
---- exercises/104_threading.zig	2024-03-05 09:09:04.013974229 +0100
+--- exercises/104_threading.zig	2024-04-10 19:12:29.878856370 +0200
-+++ answers/104_threading.zig	2024-03-05 09:12:03.987162883 +0100
++++ answers/104_threading.zig	2024-04-10 19:11:22.304265713 +0200
 @@ -97,12 +97,12 @@
          defer handle.join();
  

patches/patches/106_files.patch

@@ -0,0 +1,29 @@
+--- exercises/106_files.zig	2024-03-27 16:52:05.660910200 +0800
++++ answers/106_files.zig	2024-03-27 16:52:09.649422200 +0800
+@@ -35,7 +35,7 @@
+         // by doing nothing
+         //
+         // we want to catch error.PathAlreadyExists and do nothing
+-        ??? => {},
++        error.PathAlreadyExists => {},
+         // if is any other unexpected error we just propagate it through
+         else => return e,
+     };
+@@ -44,7 +44,7 @@
+     // 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 @@
+     // but here we are not yet done writing to the file
+     // if only there are a keyword in zig that
+     // allow you "defer" code execute to the end of scope...
+-    file.close();
++    defer file.close();
+ 
+     // !you are not allow to switch this two lines to before file closing line!
+     const byte_written = try file.write("It's zigling time!");

patches/patches/107_files2.patch

@@ -0,0 +1,26 @@
+--- exercises/107_files2.zig	2024-03-27 16:51:56.199719600 +0800
++++ answers/107_files2.zig	2024-03-27 16:52:01.650935300 +0800
+@@ -33,7 +33,7 @@
+     // initalize an array of u8 with all letter 'A'.
+     // we need to pick a 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 @@
+     // 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 answer that are both vaild in this case
+-    const byte_read = zig_read_the_file_or_i_will_fight_you(&content);
++    const byte_read = try file.read(&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} byte: {s}\n", .{
+         byte_read,
+-        content, // change this line only
++        content[0..byte_read], // change this line only
+     });
+ }

test/tests.zig

@@ -152,7 +152,7 @@ const CheckNamedStep = struct {
 
     fn make(step: *Step, _: *std.Progress.Node) !void {
         const b = step.owner;
-        const self = @fieldParentPtr(CheckNamedStep, "step", step);
+        const self: *CheckNamedStep = @alignCast(@fieldParentPtr("step", step));
         const ex = self.exercise;
 
         const stderr_file = try fs.cwd().openFile(
@@ -204,7 +204,7 @@ const CheckStep = struct {
 
     fn make(step: *Step, _: *std.Progress.Node) !void {
         const b = step.owner;
-        const self = @fieldParentPtr(CheckStep, "step", step);
+        const self: *CheckStep = @alignCast(@fieldParentPtr("step", step));
         const exercises = self.exercises;
 
         const stderr_file = try fs.cwd().openFile(
@@ -327,7 +327,7 @@ const FailStep = struct {
 
     fn make(step: *Step, _: *std.Progress.Node) !void {
         const b = step.owner;
-        const self = @fieldParentPtr(FailStep, "step", step);
+        const self: *FailStep = @alignCast(@fieldParentPtr("step", step));
 
         try step.result_error_msgs.append(b.allocator, self.error_msg);
         return error.MakeFailed;
@@ -370,7 +370,7 @@ const HealStep = struct {
 
     fn make(step: *Step, _: *std.Progress.Node) !void {
         const b = step.owner;
-        const self = @fieldParentPtr(HealStep, "step", step);
+        const self: *HealStep = @alignCast(@fieldParentPtr("step", step));
 
         return heal(b.allocator, self.exercises, self.work_path);
     }