2.1 KiB
2.1 KiB
Array
The type of array is [T; Lengh]
, as you can see, array's lengh is part of their type signature. So their length must be known at compile time.
For example, you cant initialized an array as below:
fn init_arr(n: i32) {
let arr = [1; n];
}
This will cause an error, because the compile have no idea of the exact size of the array in compile time.
- π
fn main() {
// fill the blank with proper array type
let arr: __ = [1, 2, 3, 4, 5];
// modify below to make it work
assert!(arr.len() == 4);
println!("Success!")
}
- ππ
fn main() {
// we can ignore parts of the array type or even the whole type, let the compiler infer it for us
let arr0 = [1, 2, 3];
let arr: [_; 3] = ['a', 'b', 'c'];
// fill the blank
// Arrays are stack allocated, `std::mem::size_of_val` return the bytes which array occupies
// A char takes 4 byte in Rust: Unicode char
assert!(std::mem::size_of_val(&arr) == __);
println!("Success!")
}
- π All elements in an array can be initialized to the same value at once.
fn main() {
// fill the blank
let list: [i32; 100] = __ ;
assert!(list[0] == 1);
assert!(list.len() == 100);
println!("Success!")
}
- π All elements in an array must be of the same type
fn main() {
// fix the error
let _arr = [1, 2, '3'];
println!("Success!")
}
- π Indexing starts at 0.
fn main() {
let arr = ['a', 'b', 'c'];
let ele = arr[1]; // only modify this line to make the code work!
assert!(ele == 'a');
println!("Success!")
}
- π Out of bounds indexing causes
panic
.
// fix the error
fn main() {
let names = [String::from("Sunfei"), "Sunface".to_string()];
// `get` returns an Option<T>, it's safe to use
let name0 = names.get(0).unwrap();
// but indexing is not safe
let _name1 = &names[2];
println!("Success!")
}
You can find the solutions here(under the solutions path), but only use it when you need it