rust errors

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rust errors

crate 箱

$ rustc app.rs
error[E0463]: can't find crate for `ferris_says`
 --> app.rs:2:1
  |
2 | extern crate ferris_says;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.

rustc --explain E0463

A plugin/crate was declared but cannot be found.

You need to link your code to the relevant crate in order to be able to use it (through Cargo or the -L option of rustc example).

Plugins are crates as well, and you link to them the same way.

A plugin/crate was declared but cannot be found.

Erroneous code example:

\`\`\`
#![feature(plugin)]
#![plugin(cookie_monster)] // error: can't find crate for `cookie_monster`
extern crate cake_is_a_lie; // error: can't find crate for `cake_is_a_lie`
\`\`\`

You need to link your code to the relevant crate in order to be able to use it (through Cargo or the `-L` option of rustc example). 
Plugins are crates as well, and you link to them the same way.

## Common causes

## Common causes

- The crate is not present at all. If using Cargo, add it to `[dependencies]` in Cargo.toml.
- The crate is present, but under a different name. If using Cargo, look for `package = ` under `[dependencies]` in Cargo.toml.

## Common causes for missing `std` or `core`

- You are cross-compiling for a target which doesn't have `std` prepackaged.
  Consider one of the following:
  + Adding a pre-compiled version of std with `rustup target add`
  + Building std from source with `cargo build -Z build-std`
  + Using `#![no_std]` at the crate root, so you won't need `std` in the first place.
- You are developing the compiler itself and haven't built libstd from source.
  You can usually build it with `x.py build library/std`. More information about x.py is available in the [rustc-dev-guide].

[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#building-the-compiler

https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#building-the-compiler

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Rust Playground

https://play.rust-lang.org/

https://www.runoob.com/rust/rust-tutorial.html

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rust

https://www.rust-lang.org/zh-CN/learn

Cargo

https://crates.io/

https://doc.rust-lang.org/cargo/index.html

https://doc.rust-lang.org/cargo/getting-started/installation.html
https://doc.rust-lang.org/cargo/getting-started/first-steps.html

# generate a new package
$ cargo new hello_world

manifest (Cargo.toml)

https://doc.rust-lang.org/cargo/appendix/glossary.html#manifest

package

https://doc.rust-lang.org/cargo/appendix/glossary.html#package

crate

https://doc.rust-lang.org/cargo/appendix/glossary.html#crate

??? package => binary

??? library => ???

rustc

https://doc.rust-lang.org/rustc/index.html

rustdoc

https://doc.rust-lang.org/rustdoc/index.html

rustwasm

https://rustwasm.github.io/docs/book/

rust-cli

https://rust-cli.github.io/book/index.html

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ferris-says v0.2.1

A Rust flavored replacement for the classic cowsay

https://crates.io/search?q=ferris_says

https://crates.io/crates/ferris-says

Cargo.toml

[dependencies]
ferris-says = "0.2"

https://github.com/mgattozzi/ferris-says

ferris-says = "0.2.1"

https://github.com/mgattozzi/ferris-says/blob/master/fsays/Cargo.toml#L22

https://github.com/mgattozzi/ferris-says/blob/master/Cargo.toml#L1

https://github.com/mgattozzi/ferris-says/blob/master/src/lib.rs#L12

#[cfg(not(feature = "clippy"))]
const FERRIS: &[u8] = br#"
        \
         \
            _~^~^~_
        \) /  o o  \ (/
          '_   -   _'
          / '-----' \
"#;

#[cfg(feature = "clippy")]
const CLIPPY: &[u8] = br#"
        \
         \
            __
           /  \
           |  |
           @  @
           |  |
           || |/
           || ||
           |\_/|
           \___/
"#;

cowsay

https://crates.io/search?q=cowsay

cowsay is a program that generates ASCII art pictures of a cow with a message.

cowsay 是一个程序，它可以生成带有信息的奶牛的 ASCII 艺术图片。

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println 插值

https://doc.rust-lang.org/std/macro.println.html

https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Aprintln!()%3B%20%2F%2F%20prints%20just%20a%20newline%0Aprintln!(%22hello%20there!%22)%3B%0Aprintln!(%22format%20%7B%7D%20arguments%22%2C%20%22some%22)%3B%0A%7D&edition=2021

fn main() {
    println!("🦀 Hello, world!");
    println!("\n$ rustc -V");
    println!("rustc 1.63.0 (4b91a6ea7 2022-08-08)");
    // 调用 function
    add(1, 2);
}

// fn 定义 function
fn add(left: usize, right: usize) -> usize {
  // {} 插值，占位符
  println!("\n🦀 left = {}, right = {}", left, right);
  println!("🦀🦀 left + right = {}", left + right);
  println!("\n🦀🦀🦀 left = {}, right = {}, left + right = {}", left, right, left + right);
  left + right
}