Menu
When I tried to add a const array in the global scope using this code:
static NUMBERS: [i32] = [1, 2, 3, 4, 5]; I got the following error:
error: mismatched types: expected `[i32]`, found `[i32; 5]` (expected slice, found array of 5 elements) [E0308] static NUMBERS2: [i32] = [1, 2, 3, 4, 5]; ^~~~~~~~~~~~~~~ The only way I found to deal with this problem is to specify the length in the type:
static NUMBERS: [i32; 5] = [1, 2, 3, 4, 5]; Is there a better way? It should be possible to create an array without manually counting its elements.
794
An array is written as: let array: [i32; 3] = [4, 5, 6];
To declare a constant variable in rust, we use the const keyword followed by the name of the variable and its type. The syntax is as shown: const var_name: type = value; Note that you must explicitly specify the type of a constant variable, unlike normal variables in Rust.
Rust has two different types of constants which can be declared in any scope including global. Both require explicit type annotation: const : An unchangeable value (the common case). static : A possibly mut able variable with 'static lifetime.
In Rust, an array is immutable, which means we cannot change its elements once it is created. However, we can create a mutable array by using the mut keyword before assigning it to a variable.
Using [T; N] is the proper way to do it in most cases; that way there is no boxing of values at all. There is another way, though, which is also useful at times, though it is slightly less efficient (due to pointer indirection): &'static [T]. In your case:—
static NUMBERS: &'static [i32] = &[1, 2, 3, 4, 5]; You can use const for that, here is an example:
const NUMBERS: &'static [i32] = &[1, 2, 3, 4, 5]; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
