add solutions for patterns.md
This commit is contained in:
parent
5807a3147d
commit
4ba73b3969
|
@ -0,0 +1,88 @@
|
|||
1.
|
||||
```rust
|
||||
fn main() {}
|
||||
fn match_number(n: i32) {
|
||||
match n {
|
||||
// match a single value
|
||||
1 => println!("One!"),
|
||||
// fill in the blank with `|`, DON'T use `..` ofr `..=`
|
||||
2 | 3 | 4 | 5 => println!("match 2 -> 5"),
|
||||
// match an inclusive range
|
||||
6..=10 => {
|
||||
println!("match 6 -> 10")
|
||||
},
|
||||
_ => {
|
||||
println!("match 11 -> +infinite")
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
2.
|
||||
```rust
|
||||
|
||||
struct Point {
|
||||
x: i32,
|
||||
y: i32,
|
||||
}
|
||||
|
||||
fn main() {
|
||||
// fill in the blank to let p match the second arm
|
||||
let p = Point { x: 2, y: 20 }; // x can be [0, 5], y can be 10 20 or 30
|
||||
|
||||
match p {
|
||||
Point { x, y: 0 } => println!("On the x axis at {}", x),
|
||||
// second arm
|
||||
Point { x: 0..=5, y: y@ (10 | 20 | 30) } => println!("On the y axis at {}", y),
|
||||
Point { x, y } => println!("On neither axis: ({}, {})", x, y),
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
3.
|
||||
```rust
|
||||
enum Message {
|
||||
Hello { id: i32 },
|
||||
}
|
||||
|
||||
fn main() {
|
||||
let msg = Message::Hello { id: 5 };
|
||||
|
||||
match msg {
|
||||
Message::Hello {
|
||||
id: id@3..=7,
|
||||
} => println!("Found an id in range [3, 7]: {}", id),
|
||||
Message::Hello { id: newid@(10 | 11 | 12) } => {
|
||||
println!("Found an id in another range [10, 12]: {}", newid)
|
||||
}
|
||||
Message::Hello { id } => println!("Found some other id: {}", id),
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
4.
|
||||
```rust
|
||||
fn main() {
|
||||
let num = Some(4);
|
||||
let split = 5;
|
||||
match num {
|
||||
Some(x) if x < split => assert!(x < split),
|
||||
Some(x) => assert!(x >= split),
|
||||
None => (),
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
5.
|
||||
```rust
|
||||
fn main() {
|
||||
let numbers = (2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048);
|
||||
|
||||
match numbers {
|
||||
(first,..,last) => {
|
||||
assert_eq!(first, 2);
|
||||
assert_eq!(last, 2048);
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
|
@ -1,6 +1,6 @@
|
|||
# Patterns
|
||||
|
||||
ππ use `|` to match several values, use `..=` to match a inclusive range
|
||||
1. ππ use `|` to match several values, use `..=` to match a inclusive range
|
||||
```rust,editable
|
||||
|
||||
fn main() {}
|
||||
|
@ -21,7 +21,7 @@ fn match_number(n: i32) {
|
|||
}
|
||||
```
|
||||
|
||||
πππ The `@` operator lets us create a variable that holds a value at the same time we are testing that value to see whether it matches a pattern.
|
||||
2. πππ The `@` operator lets us create a variable that holds a value at the same time we are testing that value to see whether it matches a pattern.
|
||||
```rust,editable
|
||||
|
||||
struct Point {
|
||||
|
@ -42,7 +42,7 @@ fn main() {
|
|||
}
|
||||
```
|
||||
|
||||
πππ
|
||||
3. πππ
|
||||
|
||||
```rust,editable
|
||||
|
||||
|
@ -66,7 +66,7 @@ fn main() {
|
|||
}
|
||||
```
|
||||
|
||||
ππ A match guard is an additional if condition specified after the pattern in a match arm that must also match, along with the pattern matching, for that arm to be chosen.
|
||||
4. ππ A match guard is an additional if condition specified after the pattern in a match arm that must also match, along with the pattern matching, for that arm to be chosen.
|
||||
```rust,editable
|
||||
|
||||
// fill in the blank to make the code work, `split` MUST be used
|
||||
|
@ -81,7 +81,7 @@ fn main() {
|
|||
}
|
||||
```
|
||||
|
||||
ππ Ignoring remaining parts of the value with `..`
|
||||
5. ππ Ignoring remaining parts of the value with `..`
|
||||
```rust,editable
|
||||
|
||||
// fill the blank to make the code work
|
||||
|
|
Loadingβ¦
Reference in New Issue