“,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 enumColor{Red,Green,Blue,RGB(u8,u8,u8),}fnprint_color(color:Color){ifletColor::Red=color{p...
ifletx=Some(2){dbg!(x);} 其实if let还可以接else分支的,我们再来看个例子 fnmain(){letfavorite_color:Option<&str>=None;letis_tuesday=false;letage:Result<u8,_>="34".parse();ifletSome(color)=favorite_color{println!("Using your favorite color, {color}, as the background");}elseifis...
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))...
let mut offset_cursor = 0; // 3. 按照字段在源代码中的词法声明次序,逐一遍历每个字段。 for field in struct.fields_in_declaration_order() { if offset_cursor.rem_euclid(field.alignment) > 0 { // 4. 需要【对齐】当前字段 offset_cursor = offset_cursor.next_multiple_of(field.alignment); }...
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>,) ...
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...
def handle_is_instance(packet: Packet):if isinstance(packet, Header):print("header {packet.protocol} {packet.size}")elif isinstance(packet, Payload):print("payload {packet.data}")elif isinstance(packet, Trailer):print("trailer {packet.checksum} {packet.data}")else:assert False ...
coerced to String }; } fn example2(nums: &[i32]) -> Vec<i32> { let mut filtered = Vec::new(); for num in nums { filtered.push( if *num < 0 { break // ! coerced to i32 } else if *num % 2 == 0 { *num } else { continue // ! coerced to i32 } ); } filtered }...
("brand is {}", BRAND);// multiple assignment (tuple destructuring)// more on tuples later in the articlelet (status, code) = ("OK", 200);println!("status: {}, code: {}", status, code); 输出结果: pc is Inspirion XYZage is 1age is 2brand is Dellstatus: OK, code: 200...
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