Input and Output

lessons/en/chapter_10.yaml

@@ -1,10 +1,150 @@
-- title: Chapter 10 - The End
+- title: Chapter 10 - I/O
   content_markdown: >
-    It's been a joy to have you on the Tour of Rust. Ferris and the Tour of Rust
-    team sincerely hope you enjoy the journey ahead! If you 
+    In computing, `I/O` is an abbreviation for `Input/Output` operation.
+
+    The `input` is that the computer and tha algorithm receive and
+    the `output` represents the result generated based on the `input`.
+
+    Thing about `I/O` as a stream of information
+
+    A compute system without output is nearly useless.
+
+    It will always run the same code on the same data and, thus, produce the same result.
 
-    have felt comfortable this far, we strongly recommend diving deeper with
-    these resources:
+- title: Do it locally
+  content_markdown: >
+    In this chapter, the Playground will be just a code support for you :(.
+
+    Since most of the `I/O` programs are designed to compile on a local machine
+    (yours :) ), consider setting up a Rust environment on your personal computer and
+    familiarise yourself with the terminal.
+
+    Also, consider using a `IDE`, such as `VS Code` or `RustRover`
+    and familiarise yourself with the [terminal](https://www.youtube.com/watch?v=lZ7Kix9bjPI).
+
+- title: Standard Input (stdin)
+  content_markdown: >
+    `Standard Input` refers to the data provided by the user in order for the algorithm
+    to make something with it.
+
+
+    Thus, the `input` represents what a program is being given.
+    Mostly, in terms of `input`, you'll work with `String` and `files`.
+
+
+    The Rust library `std::io` has the necessary components to interact with `I/O`
+    channels, such as the keyboard or any other input source.
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Aio%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+input+%3D+String%3A%3Anew%28%29%3B%0A%0A++++%2F%2F+the+read+will+be+stopped+by+%60%5Cn%60+character%0A++++if+let+Ok%28_%29+%3D+io%3A%3Astdin%28%29.read_line%28%26mut+input%29+%7B%0A++++++++println%21%28%22Input+text+%3A+%7B%7D%22%2C+input%29%3B%0A++++%7D%0A%7D%0A
+
+- title: Standard Output (stdout)
+  content_markdown: >
+    Remember the first lesson? Can you notice something relevant to `I/O`?
+
+    Of course that `println!` is does an output operation,
+    in fact it directs (outputs) text to `stdout` (stdout)
+    and it will be displayed on the screen.
+
+    If you don't want to print a new line character `\n` for you, use `print!`
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Aio%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+input+%3D+String%3A%3Anew%28%29%3B%0A%0A++++%2F%2F+the+read+will+be+stopped+by+%60%5Cn%60+character%0A++++if+let+Ok%28_%29+%3D+io%3A%3Astdin%28%29.read_line%28%26mut+input%29+%7B%0A++++++++println%21%28%22Input+text+%3A+%7B%7D%22%2C+input%29%3B%0A++++%7D%0A%7D%0A
+
+- title: Standard Error (stdout)
+  content_markdown: >
+    In order to separate error reporting from common printing, you can use `eprint!` and
+    `eprintln!` macros that will display text in the standard error (`stderr`) channel,
+    instead of `stdout`. Use this macro with an informative message.
+
+    In UNIX-like systems, such as macOS or LINUX, you can separate the two types of
+    output by using redirections:
+    - `./main > output.txt`
+    - `./main >> output.txt`
+    - `./main 2> output.txt`
+    - `./main 2>> output.txt`
+
+
+    > The commands with `2` with copy only the errors generated by the program, and the ones without `2` will discards all error.
+
+    > THe command with `>>` will add text at the end of the file, while the operator `>` will override the file.
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Aio%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+input+%3D+String%3A%3Anew%28%29%3B%0A%0A++++%2F%2F+the+read+will+be+stopped+by+%60%5Cn%60+character%0A++++if+let+Ok%28_%29+%3D+io%3A%3Astdin%28%29.read_line%28%26mut+input%29+%7B%0A++++++++println%21%28%22Input+text+%3A+%7B%7D%22%2C+input%29%3B%0A++++%7D%0A%7D%0A
+
+- title: File Descriptors
+  content_markdown: >
+    Now that we know what are the basic `I/O` operations, we dive even deeper.
+
+    You've already seen before: `stdin` (standard input), `stdout` (standard output) and `stderr` (stand error).
+    For each of them it is associated a positive integer number, a unique identifier
+    for an `I/O` channel (example: file), known as a `file descriptor (fd)`.
 
-    * [The Official Rust Programming
-    Book](https://doc.rust-lang.org/stable/book/)
+    Therefore:
+    - `stdin`: 0
+    - `stdout`: 1
+    - `stderr`: 2
+    - files
+
+    [![file descriptors](https://cs-pub-ro.github.io/operating-systems/assets/images/file-descriptors-d19424f0a417ecd1c032f98a1969ad75.svg)
+
+
+    Working with files plays an important role in the `I/O` operations.
+
+    You've already learned to open a text file and read its content.
+
+    But how about writing data in it, as an `I/O` channel.
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Afs%3A%3A%7Bself%2C+File%7D%3B++++++%2F%2F+file+system%0Ause+std%3A%3Aio%3A%3A%7Bself%2C+Write%7D%3B+++++%2F%2F+input+output%0A%0Afn+main%28%29+-%3E+io%3A%3AResult%3C%28%29%3E+%7B%0A++++let+file_name+%3D+%22output.txt%22%3B%0A%0A++++%2F%2F+creates+the+file+if+it+doesn%27t+already+exists%0A++++let+mut+file+%3D+File%3A%3Acreate%28file_name%29%3F%3B%0A%0A++++let+text_to_write+%3D+%22Hello%2C+World%21%5Cn%5C%0A++++++++++++++++++++++++++++This+is+a+line+of+text.%5Cn%22%3B%0A++++file.write_all%28text_to_write.as_bytes%28%29%29%3F%3B%0A%0A++++let+absolute_path+%3D+fs%3A%3Acanonicalize%28file_name%29%3F%3B%0A++++println%21%28%22Text+has+been+written+to%3A+%7B%3A%3F%7D%22%2C+absolute_path%29%3B%0A%0A++++return+Ok%28%28%29%29%3B%0A%7D%0A
+
+- title: System Arguments
+  content_markdown: >
+    A Rust program is able to receive `input` from the in-line arguments.
+
+    In order to do so, open a [terminal](https://www.youtube.com/watch?v=lZ7Kix9bjPI), compile it and pass the arguments to the executable in the command promt.
+
+    These arguments might be relevant files, flags and so on.
+    The developer must document their purpose.
+
+    If you are using LINUX or macOS, bear in mind these commands:
+    ```bash
+    $ touch main.rs
+    $ rustc main.rs
+    $ ./main.rs 2 3 4 5 
+    ```
+
+    Otherwise, for Windows environment, on a PowerShell and paste them
+    ```PowerShell
+    > echo. > main.rs
+    > rustc main.rs
+    > .\main.exe 2 3 4 5
+    ```
+
+
+    > Notice that the first argument is the executable itself
+
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Aenv%3B+++++++%2F%2F+env+stands+for+environment%0A%0Afn+main%28%29+%7B%0A++++let+args%3A+Vec%3CString%3E+%3D+env%3A%3Aargs%28%29.collect%28%29%3B%0A++++println%21%28%22number+of+arguments+%3D+%7B%7D%22%2C+args.len%28%29%29%3B%0A++++println%21%28%22the+inline+arguments+are+%3A+%7B%3A%3F%7D%22%2C+args%29%3B%0A%7D%0A
+
+- title: Environment Variables
+  content_markdown: >
+    You've seen that the Rust standard library grants access to the system.
+
+    Using the `std::env` module, you can do in Rust some task that might require
+    a UNIX terminal, such as:
+    - command line arguments
+    - printing the current working directory
+    - current executable path
+    - working with environmental variables
+    - working with files and directories
+
+  code: >-
+    https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&code=use+std%3A%3Aenv%3B+++%2F%2F+for+interacting+with+the+system%27s+environment%0A%0Afn+main%28%29+%7B%0A%0A++++if+let+Ok%28current_dir%29+%3D+env%3A%3Acurrent_dir%28%29+%7B%0A++++++++if+let+Some%28pwd%29+%3D+current_dir.to_str%28%29+%7B%0A++++++++++++println%21%28%22The+current+working+directory+%3D+%7B%7D%22%2C+pwd%29%3B%0A++++++++%7D%0A++++%7D%0A%0A++++%2F%2F+%24+echo+%24PWD++++++%23+environment+variable%0A++++%2F%2F+if+you+don%27t+want+to+see+Seme%28...%29%2C+you+have+to+pattern+match+on+Ok%28%29%0A++++println%21%28%22The+current+working+directory+%3D+%7B%3A%3F%7D%22%2C+env%3A%3Avar%28%22PWD%22%29.ok%28%29%29%3B%0A%0A++++%2F%2F+%24+echo+%24PWD++++++%23+environment+variable%0A++++if+let+Ok%28pwd%29+%3D+env%3A%3Avar%28%22PWD%22%29+%7B%0A++++++++println%21%28%22The+current+working+directory+%3D+%7B%7D%22%2C+pwd%29%3B%0A++++%7D%0A%0A++++%2F%2F+%24+echo+%24USER+++++%23+environment+variable%0A++++if+let+Ok%28user%29+%3D+env%3A%3Avar%28%22USER%22%29+%7B%0A++++++++println%21%28%22The+current+user+is%3A+%7B%7D%22%2C+user%29%3B%0A++++%7D%0A%0A%0A++++%2F%2F+%24+echo+%24IDK++++++%23+I+suppose+you+didn%27t+set+this+variable+%3A%29%0A++++if+let+Err%28err%29+%3D+env%3A%3Avar%28%22IDK%22%29+%7B%0A++++++++eprintln%21%28%22IDK+%3A+%7B%7D%22%2C+err%29%3B%0A++++++++env%3A%3Aset_var%28%22IDK%22%2C+%22%3D+I+don%27t+know%22%29%3B%0A++++++++println%21%28%22IDK+%3D+%7B%3A%3F%7D%22%2C+env%3A%3Avar%28%22IDK%22%29.ok%28%29%29%3B%0A++++++++env%3A%3Aremove_var%28%22IDK%22%29%3B%0A++++%7D%0A%7D%0A
+- title: Chapter 11 - Conclusion
+  content_markdown: >
+    Now that you know the basic of Input/Output operations, you used just two
+    Rust libraries along the way, and they are standard, btw: `std::env` and `std::fs`.
+
+    Now, you can build your own file managing system, Web App or even API.
+
+    Checkout these resources:
+    - [Environment Variables](https://youtu.be/npsMN-tZNVs)
+    - [Rust API](https://youtu.be/_ccDqRTx-JU)
+

lessons/en/chapter_11.yaml

@@ -0,0 +1,10 @@
+- title: Chapter 11 - The End
+  content_markdown: >
+    It's been a joy to have you on the Tour of Rust. Ferris and the Tour of Rust
+    team sincerely hope you enjoy the journey ahead! If you 
+
+    have felt comfortable this far, we strongly recommend diving deeper with
+    these resources:
+
+    * [The Official Rust Programming
+    Book](https://doc.rust-lang.org/stable/book/)

lessons/en/chapter_4.yaml

@@ -132,7 +132,7 @@
 
     function called `unwrap` that can be useful for getting a value in a quick
     and dirty manner.  `unwrap` will:
-     
+
     1. Get the value inside Option/Result
 
     2. If the enum is of type None/Err, `panic!`

lessons/en/chapter_9.yaml

@@ -111,7 +111,7 @@
   content_markdown: >
     Rust has several keywords you can use in your `use` path to quickly get
     ahold of the module you want:
-      
+
     * `crate` - the root module of your crate
 
     * `super` - the parent module of your current module