Rust const
Created By: chatGPT
Constants in Rust are values that are bound to a name and are not allowed to change. They are defined using the
const keyword and must have a type annotation. Constants can be declared at any level, including within functions or modules, and they can be used in any scope. One of the key features of constants is that they are evaluated at compile time, which makes them faster than variables which are evaluated at runtime.const PI: f64 = 3.14159;Constants are useful for defining values that are used frequently throughout your code. For example, you might define a constant to represent the maximum number of retries for an operation. This makes your code clearer and easier to maintain because it reduces magic numbers throughout your codebase.
const MAX_RETRIES: u32 = 5;Unlike variables defined with
let, constants can be defined in any scope, including global scope. Since constants must have a specific type, you cannot initialize them with a value that could change. Constants can also be defined in unsafe code if you use them in conjunction with unsafe operations.const GREETING: &str = "Hello, Rust!";Moreover, you can use constants in other constant expressions, which allows for powerful configurations in your code. Note that they can also be referenced in array sizes, which can help create fixed-size arrays without needing to duplicate the value.
const ARRAY_SIZE: usize = 10;
let arr: [i32; ARRAY_SIZE] = [0; ARRAY_SIZE];