In Rust, a constant list is a fixed-size array that cannot be modified. Once declared, a constant list is assigned a fixed size, and its elements can be only accessed and read, but not modified.
Here's an example of defining a constant list in Rust:
`` rust
const NUMBERS: [i32; 5] = [1, 2, 3, 4, 5];
This defines a constant list named of type [i32; 5], which means it is an array of 5 signed 32-bit integers. The const keyword tells Rust that this array is a constant, and cannot be modified.
You can then use this constant list in your code for reading its elements. For example:
rust
let first_number = NUMBERS[0]; // 1
let second_number = NUMBERS[1]; // 2
You can also use a constant list in a function:
const NUMBERS: [i32; 5] = [1, 2, 3, 4, 5];
fn main() {
print_numbers(&NUMBERS);
}
fn print_numbers(numbers: &[i32; 5]) {
for num in numbers.iter() {
println!("{}", num);
}
}
`
In this example, a constant list of numbers is defined outside the main function, and then passed as a reference to the print_numbers function. The iter()` method is called on the reference to the array in order to iterate over and print each element of the array.
Overall, using constant lists in Rust can be a useful way to define and use fixed-size arrays that should not be modified.