Tuples and Arrays
Tuples and arrays are the first “compound” types we have seen. All elements of an array have the same type, while tuples can accommodate different types. Both types have a size fixed at compile time.
| Typy | Literały | |
|---|---|---|
| Tablice | [T; N] | [20, 30, 40], [0; 3] |
| Krotki | (), (T,), (T1, T2), … | (), ('x',), ('x', 1.2), … |
Przypisanie i dostęp do tablicy:
fn main() {
let mut a: [i8; 10] = [42; 10];
a[5] = 0;
println!("a: {a:?}");
}Przypisanie i dostęp do krotki:
fn main() {
let t: (i8, bool) = (7, true);
println!("t.0: {}", t.0);
println!("t.1: {}", t.1);
}Kluczowe punkty:
Tablice:
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A value of the array type
[T; N]holdsN(a compile-time constant) elements of the same typeT. Note that the length of the array is part of its type, which means that[u8; 3]and[u8; 4]are considered two different types. Slices, which have a size determined at runtime, are covered later. -
Try accessing an out-of-bounds array element. Array accesses are checked at runtime. Rust can usually optimize these checks away, and they can be avoided using unsafe Rust.
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Możemy użyć literałów do przypisania wartości do tablic.
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The
println!macro asks for the debug implementation with the?format parameter:{}gives the default output,{:?}gives the debug output. Types such as integers and strings implement the default output, but arrays only implement the debug output. This means that we must use debug output here. -
Dodanie
#, np.{a:#?}, wywołuje format “ładnego druku”, który może być łatwiejszy do odczytania.
Krotki:
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Podobnie jak tablice, krotki mają stałą długość.
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Krotki grupują wartości różnych typów w typ złożony.
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Dostęp do pól krotki można uzyskać po kropce i indeksie wartości, np.
t.0,t.1. -
The empty tuple
()is also known as the “unit type”. It is both a type, and the only valid value of that type — that is to say both the type and its value are expressed as(). It is used to indicate, for example, that a function or expression has no return value, as we’ll see in a future slide.- You can think of it as
voidthat can be familiar to you from other programming languages.
- You can think of it as