Rust学习笔记（1）

内容整理自：https://doc.rust-lang.org/book/title-page.html

Chapter 1

• check rust version

rust —version

• How to run a rust program

fn main() {
    println!("hello world");
}

• main function is the entry to run in every app
• ! means it runs a macro instead of a function
• 2 steps to run: compile and run
  • pros: run everywhere even without rust installed
  • cons: 2 steps
  • just a design tradeoff

Cargo

• What is cargo
  • build system
  • package manager
• already installed with rust
• check cargo version
  cargo —version
• Creating a project with Cargo
  cargo new hello_cargo
• packages of code are referred to as crates
• build with cargo
  cargo build
• run
  ./target/build/hello_cargo
  Or
  cargo run
• check package doc
  cargo doc --open
• quickly checks your code to make sure it compiles but doesn’t produce an executable
  cargo check
  Faster than cargo build, can be used as check your work
• release
  cargo build --release
  Build with optimizations, in target/release

Chapter 2 guessing game

• variables

let foo = 5; // immutable
let mut bar = 5; // mutable

• storing variables

io::stdin().read_line(&mut guess)
    .expect("Failed to read line");

The & indicates that this argument is a reference, which gives you a way to let multiple parts of your code access one piece of data without needing to copy that data into memory multiple times.

• Handling Potential Failure with the Result Type
  io::stdin().read_line(&mut guess).expect("Failed to read line");
  The Result types are enumerations, often referred to as enums. An enumeration is a type that can have a fixed set of values, and those values are called the enum’s variants
• print values
  println!("You guessed: {}", guess);
  {} is a placeholder