📝 Get your *FREE Rust cheat sheet* : www.letsgetrusty.com/cheatsheet

This has become my favorite RUST channel on KZfaq.

Little note about function parameters: Taking &str instead of String is good, but only if you don't need an owned String. If you do need an owned String, make sure to take a String, so the caller can decide how the owned string is generated. (For example, the caller might already have a String. If you take a &str, you need an unnecessary clone) Now to contradict myself: If you do need an owned String, it might be best to use an impl Into instead. This way, the caller can pass in a &str as well. Improves ergonomics. In the same vein, taking impl AsRef instead of &str also allows your function to take an owned string. It is trivial to put an & in front, so it's not as important as Into, but it also slightly improves ergonomics. Depending on what you actually do with it, you might even want your string input to be IntoIterator or something. This does decrease ergonomics, since the caller now needs to call chars on the string, but it does mean your function will also work with, for example, Vec. If you sometimes return an owned string and sometimes a &str, you can use Cow. For example, if you sometimes return a string literal, Cow

I think this is probably your best video yet. It's great that you've gone a little bit deeper. Programmers really need to know this stuff. Thanks for your effort.

At 20:50 you talk about fixed-length encoding using four bytes. This is what UTF-32 does. AFAIK none of the major languages uses it, but Python has an interesting take on it: When a string is created, the interpreter chooses the “best fit“ between ASCII, UTF-16, and UTF-32, so that constant indexing is always possible but not too much memory is wasted. This of course only works because Python strings are immutable.

Keep it up!! As Rust grows, you will one day be remembered as one of the O.G. Rust youtubers!

As a note on your comment at the end: The type that you said that Rust does not have would be represented by Vec in Rust applications. It is not equivalent to rune slices in Go ([]rune), but intended for the same usage. In general, go slices are similar to rust vectors. However, there is a difference between char and rune: In Go, rune is an alias for int32. In Rust, char is its own type. With Rust's emphasis on memory safety, safe Rust code cannot generate invalid chars. This means that it's behavior is different from u32, the type that it would otherwise be equivalent with. In Go, it is perfectly possible to create meaningless runes. The same is true for strings by the way, safe Rust code cannot generate invalid UTF-8 values, but no such limitation exists in Go. As I understand it, these are equivalent types between Go and Rust: - string -> &[u8] - rune -> i32 - byte -> u8 - []byte -> Vec - []rune -> Vec - [7]byte -> [u8; 7] - [7]rune -> [i32; 7] The other Rust types that we mentioned (char, &str, String, Vec, etc) have additional memory safety guarantees that Go does not provide.

Liked the little explanation of UTF-8 encoding. Thanks for making the videos. It helpful to refresh what I’ve read and get a few tips too

This might be the best string and UTF8 encoding video I’ve ever seen. So many experienced, professional programmers really do not understand how Strings actually work, even in their own language or choice. And it truly did demystify for me Rusts behavior around the different string types. Much appreciated.

I learned something new about how UTF-8 works! Thank you!

The super in-depth content I crave! Great video

Probably the best explanation of string, utf-8, ascii types I’ve encountered in my 15 year career! Keep up the good work!

Your channel is so cool, thanks for putting the effort in making these tutorials.

Great explanation of this important topic in Rust. Thank you very much!

Most people say strings in rust are complicated. For me, it makes a lot of sense how it's handled. I do quite a bit of C progamming on µCs, and there everything is char*

Nice and useful intro to Rust strings. Thanks :)

This was driving me crazy last week. Really glad to see good, thorough showcase of this concept in Rust. Appreciate your content! Keep at it, this will be big when Rust blows up.

Here a brief summary of UTF-8 encoding: - UTF-8 (Unicode Transformation Format, 8-bit) is an encoding scheme, just like ASCII, for representing Unicode characters. - In UTF-8, ASCII characters are represented using a single byte, which means that any valid ASCII text is also valid UTF-8 text. - Therefore, UTF8 is backward compatible with ASCII. - In UTF-8, characters that can be represented using a single byte (i.e., ASCII characters) are represented as themselves. - Characters that require more than one byte are encoded using a combination of multiple bytes. - A code point refers to a numerical value assigned to each character or symbol in the Unicode standard. - Code points are represented using hexadecimal notation and are typically prefixed with "U+" to distinguish them from other numerical values. - For example, character "é" (Latin Small Letter E with Acute) consists of two Unicode code points: the base character "e" (U+0065) and the combining acute accent (U+0301). When encoded in UTF-8, "é" is represented by the bytes 0xC3 0xA9. - A grapheme refers to a visual unit of a written language. It represents a single user-perceived character or a combination of characters that are displayed together. - len() function returns the number of bytes, not the number of characters in a Unicode-unaware string. - len() function returns the number of characters in case of a Unicode-aware string.

This is a great guide to a subject that has given me a ton of grief in Rust. Awesome job!

This earns you the title of professor. Hardly seen anything better explained than this!

This was great. I wish I had this when I was first learning Rust.

Amazing content for a beginner! Super helpful! Thank you very much! 🙌

splendid and thoroughly explained. Bravo!

Wow, this is extremely useful! I come from the Java world and it was really confuse me when working with Rust string, especially when I need to deal with ideographic characters. Thank you!

Very nice in depth video.

Def one of the best, light weight (and logic dense) videos I've seen regarding rust string types from a practical standpoint (concerning aspiring Rustaceans). Excellent vid.

Awesome content, thanks for your work!

Finally! A great explanation of what's going on between string slices and Strings -- thank you! I also appreciated your delving into unicode encoding -- I was worried you were going to rabbit hole on binary representations of a bit characters, but you did exactly the right thing in terms of explaining how unicode encoding works, how it solves the "where am I" when you have a pointer to an arbitrary byte in a unicode string (i.e. "am I at the start?" "where is the next char boundary?") -- I love that you explicitly mentioned that the first byte of a multicode byte string is differentiable based on the high order bits, and that it encodes the length of the multibyte sequence. You mentioned indexing into a Unicode string was a linear operation, which is true, but it's sub-linear in terms of number of bytes explicitly traversed -- if you have 4 4-byte unicode chars in a string, traversal takes only 4 operations, not 16, due to this clever encoding of the first byte.

Fantastic explanation, thank you very much! 👍

Really helpful, thanks !

Namaste brother. You’re videos are too good. Keep this format going, tackling each topic standalone or mixed if it’s contextually relevant.

You have such great videos. Learning a lot.

The thing I like about Rust is you can take a buffer out of one type and transfer it to another. Like for instance you can convert between String, Vec and Box, while keeping the same underlying buffer without reallocation and copying. Hope C++ would have this. It had node transfer in limited form for lists and in newer standard for maps.

Thanks for this refresher, I was getting pretty rusty.

you are the best one to explain the difference between the two.

what an effort man.... hats off

learn more about utf, bytes and string on 20 min video than my 4 year of uni, thanks man ✌️

really nice content man. Keep it rusty xD

Simply brilliant !!!

FINALLY, thanks bro

Shit just got serious

Very interesting video thanks!

awesome video, just a small thing. Newer programmers may be confused by the lookup vs search times for a character. For UTF-8 (or any variable length encoding) if you want to lookup the nth scalar or grapheme you need to do a linear walk through of the string to count off every time you get to the end of a sequence of bytes representing a scalar/grapheme but for a fixed length encoding (runes, UTF-32) you can rely on each unit (scalar/char/grapheme) being a fixed size and you can just skip (n - 1) * 4 bytes (UTF-32 uses 4 bytes per scalar) to land in the right place. Not sure if I just confused a bunch of people or added clarity for some.

Thank you, you demystified Unicode for me, now I see how I would implement some of the UnicodeSegmentation crate myself :)

Outstanding video.

2:04 you could create an array of chars or Vec since chars are 4 bytes long.

Thanks! 🤙

Great Video!!!!

🇺🇦 Thank you for the explanation and examples!

Thanks!

Let's get goddamn rusty!

I started with creating char arrays in C back in the day so this isn't too crazy compared to that.

Богдан, спасибо! очень крутой материал

Great content! Can you do a video of chars in Rust and unicode scalar values? After hours of searching on the Internet, I am still confused.

goated content

I really like all of your videos they are one of the best out there. You mentioned that you came from a javascript background. How did you become a pro-rust-developer? did you learn the language privately and than you searched for a job or was it a fluent transition within the company you've worked in? I'm prof. C# /Typescript/Javascript developer and would like to jump on the rust-train :-)

What's the extension you're using for type autocomplete?

This is the first time I really understood UTF-8

How do you get VSCode to show the type annotations for let bindings automatically?

10:37 wow that's so cute, thank you))

Привіт світ - was great!)

this channel is a blessing. best explanation out there. thank you

How does Rust handle interoperability between string implementations (OSString, CString, a hypothetical UTF-32 String etc.)? Is there enough compiler sugar to pass a reference to an alternate String type to &str, or is there an "IString" trait you can implement or is there a lot of myString.as_str() involved?

String in Rust made my head spin. Coming from Ruby and Python string is very easy.

As far as I understand in Go you take a string which is a slice of bytes and build another slice of int32, 1 per each unicode code points. So it's nothing special, or advantegious. You just paid for a a full string decoding once. This would be equivalent to chars().map(|c| c as u32).collect::() in Rust. But because in Rust iterators are lazy you don't pay for creation of a new vector each time unless you explicitly want to.

I'm a little late, but what is the binary? And how does it differ from the stack and heap?

Hey bro, thanks for video. Do you use rust for blockchain development? The guys at Solana would love to have a series on that development on solana!

Okay... it's been about a month, but you can just use a Vec for constant time lookups.

I am trying switch over as well from nodejs still struggling with rust..

I know about the stack and the heap (and the register), but I've never heard of the "application's binary". What is it? Do you have another video where you explain it? Thanks!

cool man

Дякую за вашу працю.

18:03 Namaste!

interesting that you see ASCII as a map from integers to characters and not a map from characters to integers :)

wow. I'm from JS too

Excuse me! Can you tell me how your vscode can show type of rust variable on the left side? Thanks a lot

"Applications binary" - is is the a static memory?

Definitely learnt unicode.. thanks!!.. wondering how this complexity is being hidden in other languages 🤔..

Hey do u get the warning that says something like could not access incremental compilation directory?.

How do you enter emoji in your code?

The proliferation of code pages was an issue many years before the world wide web hit critical mass. Not everyone developed code to run in only one Country/Region.

Y U no have THANKS button? I would have bought you a pint! Thanks mate, fantastic explanation. Had some aha moments. Thanks again

What is string slice?

Nice Video :) GOD Help

what is byte?

Good stuff! Just getting into Rust as a mainly JS-Dev and this is by far the best content out there! One question: What VS-Code extension are you using, that shows these greyed out type-annotations and function-parameters?

I love the Namaste 🙏

What intrigues me is that, according to that explanation, in UTF-8 we should have 2,164,864 possibilities and not 1,112,064. So lets see: - 1 byte characters (0xxxxxxx): 2^(7) possibilities = 128 possibilities - 2 bytes characters (110xxxxx 10xxxxxx): 2^(11) possibilities = 2,048 possibilities - 3 bytes characters (1110xxxx 10xxxxxx 10xxxxxx): 2^(16) possibilities = 65,536 possibilities - 4 bytes characters (11110xxx 10xxxxxx 10xxxxxx 10xxxxxx): 2^(21) possibilities = 2,097,152 possibilities Total possibilities of characters: 128 + 2,048 + 65,536 + 2,097,152 = 2,164,864 So why 1,112,064?

Your tutorials are the best in Rust I've seen! Your English is also gorgeous. I didn't know you were Ukrainian before this video. Glory to Ukraine 🇺🇦 from Kazakhstan 🇰🇿

Why is there both to_string() and to_owned()?

ACII ? what is ascii?

Дякую (:

please teach me about integers? what are integers?

what is emoji?

Hello, happy to subscribe to your channel. Would you please say few words why an absolute beginner would rather get more motivated to learn Rust rather than say Python (or any other language that is closer to the English language syntax, ie easier ). Thank you kindly

Nice shirt

Why to expose the complexities of UTF8 encoding to programmers when most of time it is the user perceived chars to deal with?

whats is binary?

#amflearningbydoing #amflearning your content awesome, make us smart and smarter than before (smartest) right now, yeaaah coolll

Whats is STR?