let mut v1_iter = v1.iter(); // std::slice::Iter<'_, {integer}> // iter() -- borrow as immutable, 不能进行修改 // if let Some(first) = v1_iter.next() { // *first += 4; // } assert_eq!(v1_iter.next(), Some(&1)); assert_eq!(v1_iter.next(), Some(&2))...
print_color函数使用match表达式匹配输入的color枚举值,如果是Color::Red则打印"The color is red!“,如果是Color::RGB(_, 0, 0)则打印"The color is some shade of red.”,否则打印"The color is not red."。 除了使用match表达式外,我们还可以使用if let表达式来简化匹配。 代码语言:javascript 复制 enum...
("Value for name: {name}"); } if let Some(age) = matches.get_one::<u8>("age") { println!("Value for age: {age}"); } } 这段代码分为以下几个部分: 1. 创建命令行应用实例: let matches = Command::new("MyApp") 这里使用 Command::new 方法创建了一个新的命令行应用实例,命名...
Differently optimized code between `let else` and `if` #118922 commented on Feb 14, 2025 • 0 new comments `impl fmt::Display for u32` compiles to large binary #118940 commented on Feb 14, 2025 • 0 new comments SEE-AVX-stall when using target-cpu=znver2. Thus ~25 times...
模式匹配是 Rust 中一种非常强大的错误处理机制，而且提供多种使用方式：我们可以使用 if let else 和 let else，二者都涉及模式匹配，后文将具体介绍。// backend/src/router.rspub async fn login( State(mut state): State<AppState>, jar: PrivateCookieJar, Json(login): Json<LoginDetails>,) ...
while let Some(Ok(mut msg)) = stream.next().await { msg.push_str(" ️"); sink.send(msg).await?; }We get message from the stream, add a heart to it, and then send it to the sink. If we wanted to be fancy we could have also mapped the stream and forward it to ...
{// 如果是IPv4数据包letheader=Ipv4Packet::new(ethernet.payload());// 解析IPv4头部ifletSome(header)=header{match header.get_next_level_protocol(){IpNextHeaderProtocols::Tcp=>{// 如果是TCP协议lettcp=TcpPacket::new(header.payload());// 解析TCP头部ifletSome(tcp)=tcp{println!("Got a TCP ...
if let Some(splashscreen) = window.get_window("splashscreen") { splashscreen.close().unwrap(); } // 展示主视图 window.get_window("main").unwrap().show().unwrap(); } fn main() { tauri::Builder::default() // 注册命令 .invoke_handler(tauri::generate_handler![close_splashscreen]) ...
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letx=vec![10,20,30];ifc{f(x);// ... ok to move from x here}else{g(x);// ... and ok to also move from x here}h(x)// bad: x is uninitialized here if either path uses it For similar reasons, moving from a variable in a loop is forbidden: ...