太谷县建设局网站,查询个人证件证书查询,贵港网站建设公司,app怎么创建文章目录 一、Vec1.Vec与堆栈2.什么时候需要Vec3.get()方法4.与枚举的结合 二、VecDeque1.什么情况适合VecDeque2.VecDeque的方法 三、LinkedList1.什么时候用LinkedList 参考 一、Vec
可变数组(vector)数组存储在heap上,在运行时(runtime)可以增加或减少数组
长度
有人把Ve… 文章目录 一、Vec1.Vec与堆栈2.什么时候需要Vec3.get()方法4.与枚举的结合 二、VecDeque1.什么情况适合VecDeque2.VecDeque的方法 三、LinkedList1.什么时候用LinkedList 参考 一、Vec
可变数组(vector)数组存储在heap上,在运行时(runtime)可以增加或减少数组
长度
有人把Vector翻译为矢量注意默认还是不可变
1.Vec与堆栈
Vec的buf是存储在heap上的其他存储在栈上
pub struct VecT, #[unstable(feature allocator_api, issue 32838)] A:AlocatorGlobal
{
buf: RawVecT, A,
len: usize, //长度
}pub(crate) struct RawVecT, A: Allocator Global {
ptr: UniqueT, // 指向
cap: usize, // capacity
alloc: A,
}2.什么时候需要Vec
·首选Vec:当你不知道用什么的时候试试Vec性能强悍有保证 ·当你想要一个长度实时变化的数据存储单元时 ·当你希望自己的存储单元有序时 ·当你希望内存中各个元素的存储地址是连续时
#[derive(Debug, Clone)]
struct Car {id: i32,name: String,
}fn main() {// 初始化方法let my_vec vec![2, 3, 4];println!({:#?}: {}, my_vec, my_vec.capacity());// /这里的语法表示创建一个长度为 3 的向量并用 2 填充每个元素let my_vec vec![2; 3];println!({:#?}: {}, my_vec, my_vec.capacity());// 可以显示声明类型也可以不显示声明类型let my_vec: Veci32 Vec::new();println!({:#?}: {}, my_vec, my_vec.capacity());let my_vec: Veci32 Vec::with_capacity(5);println!({:#?}: {}, my_vec, my_vec.capacity());// pushlet mut cars Vec::new();for i in 1..11 {let car_type if i % 2 0 { car } else { bus };cars.push(Car {id: i,name: format!({}-{}, car_type, i),});}println!({:?}, cars);//删除poplet car cars.pop().unwrap();println!({:?}, cars);println!({:?}, car);//删除固定index删除let car cars.remove(0);println!({:?}, cars);println!({:?}, car);//队尾插入pushcars.push(car.clone());println!({:?}, cars);// 队首插入insertcars.insert(0, car.clone());println!({:?}, cars);// get set// 不推荐cars[9] Car {id: 11,name: car-11.to_string(),};println!({:?}, cars);// 推荐let item cars.get(0);println!({:?}, item);let item cars.get_mut(9).unwrap();*item Car {id: 10,name: car-10.to_owned(),};println!({:?}, cars);let mut cars2 vec![car.clone(), car.clone()];cars.append(mut cars2);println!({:?}, cars);println!({:?}, cars2);let car_slice cars.as_slice();println!({:?}, car_slice);// 清理cars.clear();println!({:?}, cars);println!({:?}, cars.is_empty());
}
编译及运行
cargo runCompiling data_struct v0.1.0 (/home/wangji/installer/rust/data_struct/data_struct)
warning: fields id and name are never read-- src/main.rs:3:5|
2 | struct Car {| --- fields in this struct
3 | id: i32,| ^^
4 | name: String,| ^^^^| note: Car has derived impls for the traits Clone and Debug, but these are intentionally ignored during dead code analysis note: #[warn(dead_code)] on by defaultwarning: data_struct (bin data_struct) generated 1 warningFinished dev profile [unoptimized debuginfo] target(s) in 5.81sRunning target/debug/data_struct
[2,3,4,
]: 3
[2,2,2,
]: 3
[]: 0
[]: 5
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 10, name: car-10 }]
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }]
Car { id: 10, name: car-10 }
[Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }]
Car { id: 1, name: bus-1 }
[Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 1, name: bus-1 }]
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 1, name: bus-1 }]
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 11, name: car-11 }]
Some(Car { id: 1, name: bus-1 })
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 10, name: car-10 }]
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 10, name: car-10 }, Car { id: 1, name: bus-1 }, Car { id: 1, name: bus-1 }]
[]
[Car { id: 1, name: bus-1 }, Car { id: 2, name: car-2 }, Car { id: 3, name: bus-3 }, Car { id: 4, name: car-4 }, Car { id: 5, name: bus-5 }, Car { id: 6, name: car-6 }, Car { id: 7, name: bus-7 }, Car { id: 8, name: car-8 }, Car { id: 9, name: bus-9 }, Car { id: 10, name: car-10 }, Car { id: 1, name: bus-1 }, Car { id: 1, name: bus-1 }]
[]
true3.get()方法 #![allow(unused)]
fn main() {
let v vec![1, 2, 3, 4, 5];let third: i32 v[2];
println!(The third element is {}, third);match v.get(2) {Some(third) println!(The third element is {}, third),None println!(There is no third element.),
}
}
~/installer/rust/bobo/abc master
cargo runCompiling abc v0.1.0 (/home/wangji/installer/rust/bobo/abc)Finished dev profile [unoptimized debuginfo] target(s) in 7.48sRunning target/debug/abc
The third element is 3
The third element is 3
~/installer/rust/bobo/abc master
4.与枚举的结合 #![allow(unused)]
fn main() {enum SpreadsheetCell {Int(i32),Float(f64),Text(String),}let row vec![SpreadsheetCell::Int(3),SpreadsheetCell::Text(String::from(blue)),SpreadsheetCell::Float(10.12),];match row[1] {SpreadsheetCell::Int(i) println!(Found an int: {}, i),_ println!(No int found),}
}
编译及运行
cargo runCompiling abc v0.1.0 (/home/wangji/installer/rust/bobo/abc)Finished dev profile [unoptimized debuginfo] target(s) in 0.29sRunning target/debug/abc
No int found二、VecDeque
一个双向的动态数组
与Vec 类似与Vec 不同的是,它对容器的两端进行 移除和插入
VecDeque的两端插入、删除都是O1级别的
VecDeque并一定是连续的
1.什么情况适合VecDeque
有双端插入和删除需求的
双向需求queue
2.VecDeque的方法
继承了Vec的所有方法
自身的方法
push_back\push_front (取代了push)
pop_frontlpop_back(取代了pop)
contains
frontifront_mut
back\back_mutExample
use std::collections::VecDeque;
#[derive(Debug, Clone)]
struct Car {id: i32,name: String,
}fn main() {let mut int_queue: VecDequei32 VecDeque::new();println!({:?} cap {}, int_queue, int_queue.capacity());int_queue.push_back(3);println!({:?} cap {}, int_queue, int_queue.capacity());let mut int_queue: VecDequei32 VecDeque::with_capacity(20);println!({:?} cap {}, int_queue, int_queue.capacity());let mut cars VecDeque::from([Car {id: 1,name: String::from(Car-1),},Car {id: 2,name: String::from(Car-2),},Car {id: 3,name: String::from(Car-3),},]);println!({:?} cap {}, cars, cars.capacity());// VecDeque// pushcars.push_back(Car {id: 4,name: Car-4.to_string(),});println!({:?} cap {}, cars, cars.capacity());cars.push_front(Car {id: 0,name: Car-0.to_string(),});println!({:?} cap {}, cars, cars.capacity());// poplet back_car cars.pop_back();println!({:?}, back_car);println!({:?} cap {}, cars, cars.capacity());let front_car cars.pop_front();println!({:?} , front_car);println!({:?} cap {}, cars, cars.capacity());// front// backprintln!({:?}, cars.front());println!({:?}, cars.back());// getprintln!(car{:?}, cars[1]); //不安全操作let car cars.get(1).unwrap(); //安全操作println!(car{:?}, car);let car cars.get_mut(1).unwrap();*car Car {id: 10,name: Car-n.to_owned(),};println!(car{:?}, cars);cars.clear();println!({:?}, cars.is_empty());
}
编译及运行
cargo runBlocking waiting for file lock on build directoryCompiling data_struct v0.1.0 (/home/wangji/installer/rust/data_struct/data_struct)
warning: variable does not need to be mutable-- src/main.rs:13:9|
13 | let mut int_queue: VecDequei32 VecDeque::with_capacity(20);| ----^^^^^^^^^| || help: remove this mut| note: #[warn(unused_mut)] on by defaultwarning: fields id and name are never read-- src/main.rs:4:5|
3 | struct Car {| --- fields in this struct
4 | id: i32,| ^^
5 | name: String,| ^^^^| note: Car has derived impls for the traits Clone and Debug, but these are intentionally ignored during dead code analysis note: #[warn(dead_code)] on by defaultwarning: data_struct (bin data_struct) generated 2 warnings (run cargo fix --bin data_struct to apply 1 suggestion)Finished dev profile [unoptimized debuginfo] target(s) in 8.30sRunning target/debug/data_struct
[] cap 0
[3] cap 4
[] cap 20
[Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }] cap 3
[Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }, Car { id: 4, name: Car-4 }] cap 6
[Car { id: 0, name: Car-0 }, Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }, Car { id: 4, name: Car-4 }] cap 6
Some(Car { id: 4, name: Car-4 })
[Car { id: 0, name: Car-0 }, Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }] cap 6
Some(Car { id: 0, name: Car-0 })
[Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }] cap 6
Some(Car { id: 1, name: Car-1 })
Some(Car { id: 3, name: Car-3 })
carCar { id: 2, name: Car-2 }
carCar { id: 2, name: Car-2 }
car[Car { id: 1, name: Car-1 }, Car { id: 10, name: Car-n }, Car { id: 3, name: Car-3 }]
true三、LinkedList
通过链式存储数据的一种序列数据结构
A double-linked with owned nodes
1.什么时候用LinkedList
·根据Rust文档LinkedList数据结构在分割/追加方面是高效的
如果您希望对分配多少内存以及何时分配内存有非常细粒度的控制那么链表是一个不错的选择。但是绝大多数你用不到而且你要考虑成本
use std::collections::LinkedList;#[derive(Debug, Clone)]
struct Car {id: i32,name: String,
}
// vecque 方法都有
// vec 无
fn main() {let mut int_link: LinkedListi32 LinkedList::new();let mut cars LinkedList::from([Car {id: 1,name: Car-1.to_string(),},Car {id: 2,name: Car-2.to_string(),},Car {id: 3,name: Car-3.to_string(),},]);cars.push_back(Car {id: 4,name: Car-4.to_string(),});println!(back: {:?}, cars.back());cars.push_front(Car {id: 0,name: Car-0.to_string(),});println!(front: {:?}, cars.front());println!({:?}, cars);let car cars.pop_back().unwrap();println!({:?}, car);let car cars.pop_front().unwrap();println!({:?}, car);/*** split_off 是一个方法用于将 Vec 切成两部分。它会将 cars 向量从指定的索引位置分成两部分并返回从该位置开始的所有元素同时将这些元素从原向量中移除。*/let mut car_list cars.split_off(cars.len() - 2);println!(---{:?}, car_list);println!({:?}, cars);cars.append(mut car_list);println!({:?}, cars);println!({:?}, car_list);cars.clear();println!({}, cars.is_empty());
}
编译及运行
cargo runCompiling data_struct v0.1.0 (/home/wangji/installer/rust/data_struct/data_struct)
warning: unused doc comment-- src/main.rs:44:5|
44 | / /**
45 | | * split_off 是一个方法用于将 Vec 切成两部分。它会将 cars 向量从指定的索引位置分成两部分并返回从该位置开始的所有元素同时将这些元素从原向量中移除。
46 | | */| |_______^
47 | let mut car_list cars.split_off(cars.len() - 2);| -------------------------------------------------- rustdoc does not generate documentation for statements| help: use /* */ for a plain comment note: #[warn(unused_doc_comments)] on by defaultwarning: unused variable: int_link-- src/main.rs:11:13|
11 | let mut int_link: LinkedListi32 LinkedList::new();| ^^^^^^^^ help: if this is intentional, prefix it with an underscore: _int_link| note: #[warn(unused_variables)] on by defaultwarning: variable does not need to be mutable-- src/main.rs:11:9|
11 | let mut int_link: LinkedListi32 LinkedList::new();| ----^^^^^^^^| || help: remove this mut| note: #[warn(unused_mut)] on by defaultwarning: fields id and name are never read-- src/main.rs:5:5|
4 | struct Car {| --- fields in this struct
5 | id: i32,| ^^
6 | name: String,| ^^^^| note: Car has derived impls for the traits Clone and Debug, but these are intentionally ignored during dead code analysis note: #[warn(dead_code)] on by defaultwarning: data_struct (bin data_struct) generated 4 warnings (run cargo fix --bin data_struct to apply 1 suggestion)Finished dev profile [unoptimized debuginfo] target(s) in 6.13sRunning target/debug/data_struct
back: Some(Car { id: 4, name: Car-4 })
front: Some(Car { id: 0, name: Car-0 })
[Car { id: 0, name: Car-0 }, Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }, Car { id: 4, name: Car-4 }]
Car { id: 4, name: Car-4 }
Car { id: 0, name: Car-0 }
---[Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }]
[Car { id: 1, name: Car-1 }]
[Car { id: 1, name: Car-1 }, Car { id: 2, name: Car-2 }, Car { id: 3, name: Car-3 }]
[]
true参考
Rust常用数据结构教程
