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let num = 23;
match num {
1 => println!("один"),
2 => println!("два"),
3 => println!("три"),
_ => println!("непонятно")
}
let num = 3;
let result = match num {
1 => "один",
2 => "два",
3 => "три",
_ => "непонятно"
};
println!("result = {}", result); // result = три
fn factorial(num: u64) -> u64 {
match num {
0 | 1 => 1,
_ => factorial(num - 1) * num,
}
}
fn exp(x: u64, n: u64) -> u64 {
match n {
0 => 1,
1 => x,
i if i % 2 == 0 => exp(x * x, n / 2),
_ => x * exp(x * x, (n - 1) / 2),
}
}
#[derive(Debug)] // so we can inspect the state in a minute
enum UsState {
Alabama,
Alaska,
// --snip--
}
enum Coin {
Penny,
Nickel,
Dime,
Quarter(UsState),
}
fn value_in_cents(coin: Coin) -> u8 {
match coin {
Coin::Penny => {
println!("Lucky penny!");
1
}
Coin::Nickel => 5,
Coin::Dime => 10,
Coin::Quarter(state) => {
println!("State quarter from {:?}!", state);
25
}
}
}
fn plus_one(x: Option<i32>) -> Option<i32> {
match x {
None => None,
Some(i) => Some(i + 1),
}
}
let five = Some(5);
let six = plus_one(five);
let none = plus_one(None);
let dice_roll = 9;
match dice_roll {
3 => add_fancy_hat(),
7 => remove_fancy_hat(),
other => move_player(other),
}
fn add_fancy_hat() {}
fn remove_fancy_hat() {}
fn move_player(num_spaces: u8) {}
let dice_roll = 9;
match dice_roll {
3 => add_fancy_hat(),
7 => remove_fancy_hat(),
_ => reroll(),
}
fn add_fancy_hat() {}
fn remove_fancy_hat() {}
fn reroll() {}
let dice_roll = 9;
match dice_roll {
3 => add_fancy_hat(),
7 => remove_fancy_hat(),
_ => (),
}
fn add_fancy_hat() {}
fn remove_fancy_hat() {}
let config_max = Some(3u8);
match config_max {
Some(max) => println!("The maximum is configured to be {}", max),
_ => (),
}
// или
let config_max = Some(3u8);
if let Some(max) = config_max {
println!("The maximum is configured to be {}", max);
}
let mut count = 0;
match coin {
Coin::Quarter(state) => println!("State quarter from {:?}!", state),
_ => count += 1,
}
// или
let mut count = 0;
if let Coin::Quarter(state) = coin {
println!("State quarter from {:?}!", state);
} else {
count += 1;
}
fn main() {
let p = Point { x: 0, y: 7 };
match p {
Point { x, y: 0 } => println!("On the x axis at {x}"),
Point { x: 0, y } => println!("On the y axis at {y}"),
Point { x, y } => {
println!("On neither axis: ({x}, {y})");
}
}
}
// On the y axis at 7
enum Message {
Quit,
Move { x: i32, y: i32 },
Write(String),
ChangeColor(i32, i32, i32),
}
fn main() {
let msg = Message::ChangeColor(0, 160, 255);
match msg {
Message::Quit => {
println!("The Quit variant has no data to destructure.");
}
Message::Move { x, y } => {
println!("Move in the x direction {x} and in the y direction {y}");
}
Message::Write(text) => {
println!("Text message: {text}");
}
Message::ChangeColor(r, g, b) => {
println!("Change the color to red {r}, green {g}, and blue {b}",)
}
}
}
// Change the color to red 0, green 160, and blue 255
enum Color {
Rgb(i32, i32, i32),
Hsv(i32, i32, i32),
}
enum Message {
Quit,
Move { x: i32, y: i32 },
Write(String),
ChangeColor(Color),
}
fn main() {
let msg = Message::ChangeColor(Color::Hsv(0, 160, 255));
match msg {
Message::ChangeColor(Color::Rgb(r, g, b)) => {
println!("Change color to red {r}, green {g}, and blue {b}");
}
Message::ChangeColor(Color::Hsv(h, s, v)) => {
println!("Change color to hue {h}, saturation {s}, value {v}")
}
_ => (),
}
}
// Change color to hue 0, saturation 160, value 255
let mut setting_value = Some(5);
let new_setting_value = Some(10);
match (setting_value, new_setting_value) {
(Some(_), Some(_)) => {
println!("Can't overwrite an existing customized value");
}
_ => {
setting_value = new_setting_value;
}
}
println!("setting is {:?}", setting_value);
let numbers = (2, 4, 8, 16, 32);
match numbers {
(first, _, third, _, fifth) => {
println!("Some numbers: {first}, {third}, {fifth}")
}
}
struct Point {
x: i32,
y: i32,
z: i32,
}
let origin = Point { x: 0, y: 0, z: 0 };
match origin {
Point { x, .. } => println!("x is {}", x),
}
let numbers = (2, 4, 8, 16, 32);
match numbers {
(first, .., last) => {
println!("Some numbers: {first}, {last}");
}
}
fn describe_point(point: (i32, i32)) {
match point {
(0, _) => println!("на оси Y"),
(_, 0) => println!("на оси X"),
(x, _) if x < 0 => println!("слева от оси Y"),
(_, y) if y < 0 => println!("ниже оси X"),
_ => println!("первый квадрант"),
}
}
let num = Some(4);
match num {
Some(x) if x % 2 == 0 => println!("The number {} is even", x),
Some(x) => println!("The number {} is odd", x),
None => (),
}
// The number 4 is even
let x = Some(5);
let y = 10;
match x {
Some(50) => println!("Got 50"),
Some(n) if n == y => println!("Matched, n = {n}"),
_ => println!("Default case, x = {:?}", x),
}
println!("at the end: x = {:?}, y = {y}", x);
// Default case, x = Some(5)
// at the end: x = Some(5), y = 10
let x = 4;
let y = false;
match x {
4 | 5 | 6 if y => println!("yes"),
_ => println!("no"),
}
Оператор at (@) позволяет создать переменную, которая содержит значение, одновременно с тем, как мы проверяем, соответствует ли это значение шаблону.
enum Message {
Hello { id: i32 },
}
let msg = Message::Hello { id: 5 };
match msg {
Message::Hello {
id: id_variable @ 3..=7,
} => println!("Found an id in range: {}", id_variable),
Message::Hello { id: 10..=12 } => {
println!("Found an id in another range")
}
Message::Hello { id } => println!("Found some other id: {}", id),
}
// Found an id in range: 5
#[rustfmt::skip]
fn main() {
let input = 'x';
match input {
'q' => println!("выход"),
'a' | 's' | 'w' | 'd' => println!("движение"),
'0'..='9' => println!("число"),
key if key.is_lowercase() => println!("буква в нижнем регистре: {key}"),
_ => println!("другое"),
}
}
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