本文档记录rust的学习历程，并摘录rust的使用技巧，备用！
###创建文件 touch ~/.cargo/config ###添加以下内容 #替换为中科大的镜像源 [source.crates-io] registry = "https://github.com/rust-lang/crates.io-index" replace-with = 'ustc' #清华 [source.tuna] registry = "https://mirrors.tuna.tsinghua.edu.cn/git/crates.io-index.git" #中科大 [source.ustc] registry = "git://mirrors.ustc.edu.cn/crates.io-index" #上交 [source.sjtu] registry = "https://mirrors.sjtug.sjtu.edu.cn/git/crates.io-index" #rustcc社区 [source.rustcc0] registry = "https://code.aliyun.com/rustcc/crates.io-index.git" [source.rustcc1] registry="git://crates.rustcc.cn/crates.io-index" [source.rustcc2] registry="git://crates.rustcc.com/crates.io-index"
- shadow可改变变量类型，而mut本质上为同一个对象
###shadow, 两个x虽然相同命名，但后者覆盖了前者 ###指向不同的对象 let x = 5; let x = x+1;
###强制指定为可变对象，可直接对其操作 let mut x = 5; x = x+1;
the compiler guarantees that references will never be dangling references
- can have only one mutable reference to a particular piece of data in a particular scope
- cannot have a mutable reference while we have an immutable one
###由于ownership转移，s1不能在println中继续使用
fn main() {
let s1 = String::from("hello");
let (s2, len) = calculate_length(s1);
println!("The length of '{}' is {}.", s2, len);
}
fn calculate_length(s: String) -> (String, usize) {
let length = s.len();
(s, length)
}
###借助reference，可以不必一直通过参数、返回值传递拥有权
###称为borrowing
fn main() {
let s1 = String::from("hello");
let len = calculate_length(&s1);
println!("The length of '{}' is {}.", s1, len);
}
fn calculate_length(s: &String) -> usize {
s.len()
}
- Each value in Rust has a variable that’s called its owner
- There can only be one owner at a time
- When the owner goes out of scope, the value will be dropped
- assigning a value to another variable moves it
设计原则
- Rust will never automatically create “deep” copies of your data
- A package
- cargo new xxx
is one or more crates that provide a set of functionality contains a Cargo.toml file that describes how to build those crates:
must contain zero or one library crates, and no more can contain as many binary crates as you'd like must contain at least one crate (either library or binary) - A crate
- cargo new –lib xxx
a binary or library:
crate root 'src/main.rs' for binary crate 'src/lib.rs' for library crate 'src/bin' for multiple binary crate
- A module
useful for organizing your code, also define Rust’s privacy boundary:
all items are private by default, 'pub' make items public
- A path
- name items
'use' brings a path into scope
similar to tuples, pieces of a struct can be different types Unlike with tuples, you’ll name each piece of data
Tuple structs are useful when you want to give the whole tuple
a name and make the tuple be a different type from other tuples
struct Color(i32, i32, i32);
Unit-like structs can be useful in situations in which you need
to implement a trait on some type but don’t have any data that
you want to store in the type itself.
struct test();
a null is a value that is currently invalid or absent for some reason
Rust does not have nulls, but it does have an enum that can encode the concept of a value being present or absent.
enum Option<T> {
Some(T),
None,
}
使用 ? 传递错误，大大简化了 match 语法
如果经过以下3条原则，仍然无法确定返回值的lifetime，则必须人工指定
- each parameter that is a reference gets its own lifetime parameter
fn foo<'a, 'b>(x: &'a i32, y: &'b i32); - if there is exactly one input lifetime parameter, that lifetime is assigned to all output lifetime parameters
fn foo<'a>(x: &'a i32) -> &'a i32 - if there are multiple input lifetime parameters, but one of them is
&selfor&mut selfbecause this is a method, the lifetime of self is assigned to all output lifetime parameters
- 更新rust
rustc --version rustup update - 新建工程
cargo new --cvs=none hello-rust 未指定版本管理工具, 默认 --cvs=git - 语法检查
cargo check - 编译
cargo build cargo build --release - 编译+运行
cargo run - 当前项目依赖的帮助文档(在浏览器打开)
cargo doc --open