Constants vs Static Variables

Snippet

Constants vs Static Variables

Constants are inlined at compile time and can be used anywhere. Static variables are stored in memory at a fixed address and live for the entire program duration. Static mut requires unsafe blocks for access due to Rust's safety guarantees against data races.

snippet.rs

rust

const GRAVITY: f64 = 9.81;
static mut COUNTER: u32 = 0;
 
fn main() {
    println!("Gravity: {}", GRAVITY);
    
    unsafe {
        COUNTER += 1;
        println!("Counter: {}", COUNTER);
    }
}

Breakdown

const GRAVITY: f64 = 9.81;

Compile-time constant, inlined everywhere it's used

static mut COUNTER: u32 = 0;

Mutable static variable with fixed memory address

unsafe {

Required block for accessing static mut

COUNTER += 1;

Direct mutation of static variable

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Constants vs Static Variables

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