PS F:\learn\rustlearn>> cargo new learn30Created binary (application) `learn30` package PS F:\learn\rustlearn>> cd learn30 PS F:\learn\rustlearn\learn30>> ls目錄: F:\learn\rustlearn\learn30Mode LastWriteTime Length Name ---- ------------- ------ ---- d----- 2020-03-10 14:05 src -a---- 2020-03-10 14:05 8 .gitignore -a---- 2020-03-10 14:05 204 Cargo.tomlPS F:\learn\rustlearn\learn30>>PS F:\learn\rustlearn\learn30>> cat Cargo.toml [package] name = "learn30" version = "0.1.0" authors = ["Administrator"] edition = "2018"# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html[dependencies]

編輯src/main.rs文件

pub enum Status{Start,Stop,Pause, } pub fn print_info(now_status:Status)->(){match now_status{Status::Start=> println!("start"), Status::Stop=> println!("stop"),Status::Pause=> println!("pause"), } } fn main() {let s1=Status::Start;let s2=Status::Stop;let s3=Status::Pause; print_info(s1);print_info(s2);print_info(s3); } PS F:\learn\rustlearn\learn30>> cargo buildCompiling learn30 v0.1.0 (F:\learn\rustlearn\learn30)Finished dev [unoptimized + debuginfo] target(s) in 0.67s PS F:\learn\rustlearn\learn30>> pub enum Option{Some(i32),None, }fn main() {let s1=Some(16);let s2=s1.unwrap();match s1{Some(n)=>println!("num {}",s2), None=>(),}; } PS F:\learn\rustlearn\learn32> cargo buildCompiling learn32 v0.1.0 (F:\learn\rustlearn\learn32) warning: unused variable: `n`--> src\main.rs:10:11| 10 | Some(n)=>println!("num {}",s2),| ^ help: consider prefixing with an underscore: `_n`|= note: `#[warn(unused_variables)]` on by defaultFinished dev [unoptimized + debuginfo] target(s) in 0.61s PS F:\learn\rustlearn\learn32> cargo run warning: unused variable: `n`--> src\main.rs:10:11| 10 | Some(n)=>println!("num {}",s2),| ^ help: consider prefixing with an underscore: `_n`|= note: `#[warn(unused_variables)]` on by defaultFinished dev [unoptimized + debuginfo] target(s) in 0.05sRunn

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