Array
- Rust course
- Beginner
- Lesson 17/115
- 4 min
Learn fixed-size arrays of type [T; n].
Arrays
An array holds a fixed number of elements of the same type on the stack. Its type is [T; N] and the length is part of the type:
let notlar: [i32; 4] = [70, 85, 90, 55];
let sifirlar = [0; 5]; // [0, 0, 0, 0, 0]
println!("{} {}", notlar[0], notlar.len());An out-of-range index (e.g. notlar[10]) panics at run time; Rust never touches invalid memory. For safe reading, notlar.get(10) returns an Option.
Iterating an array
Arrays are iterated with for, and iterator methods can be used:
let notlar = [70, 85, 90, 55];
for n in notlar {
print!("{n} ");
}
let toplam: i32 = notlar.iter().sum();
let en_yuksek = notlar.iter().max().unwrap();
println!("\n{toplam} {en_yuksek}");For lists whose length changes at run time, Vec<T> is used instead of an array.
Practice Grade statistics
For let notlar = [70, 85, 90, 55];, find the sum with .iter().sum::<i32>() and the highest grade with .iter().max(), and print println!("{} {}", toplam, en_yuksek);.
Starter code
fn main() {
// buraya yaz
}Sample solution
fn main() {
let notlar = [70, 85, 90, 55];
let toplam = notlar.iter().sum::<i32>();
let en_yuksek = notlar.iter().max().unwrap();
println!("{} {}", toplam, en_yuksek);
}Expected output
300 90
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does <code>[1, 2, 3].get(5)</code> return?
- Some(0)
- None Correct answer
- A panic
- 0
Explanation: get reports the bounds check in its result: Some(&value) for a valid index, None otherwise.
2 Array type
let gunler: [&str; ____] = ["Pzt", "Sal", "Çar"];let gunler: [&str; 3] = ["Pzt", "Sal", "Çar"];Explanation: The number in an array type is the element count and must match the value.
3 Expression and result
| Term | Meaning |
|---|---|
[0; 3] |
[0, 0, 0] |
[1, 2, 3].len() |
3 |
[1, 2][5] |
panic |
[1, 2].get(5) |
None |