Merge pull request 'added exercise/106_files.zig' (#66) from dizzyi_solo/exercises:main into main

Reviewed-on: https://codeberg.org/ziglings/exercises/pulls/66
This commit is contained in:
Chris Boesch 2024-03-27 18:54:51 +00:00
commit 20919722ff
6 changed files with 211 additions and 0 deletions

1
.gitignore vendored
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@ -2,3 +2,4 @@
/zig-out/
/answers/
/patches/healed/
/output/

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@ -1121,6 +1121,17 @@ 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 =

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exercises/106_files.zig Normal file
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@ -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?

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exercises/107_files2.zig Normal file
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//
// 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
});
}

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@ -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!");

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@ -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
});
}