2.5 Constants and Statics

2.5.1 Constants

Constants are immutable values that are set at compile time.

const MAX_POINTS: u32 = 100_000;

fn main() {
    println!("The maximum points are: {}", MAX_POINTS);
}
  • Must include type annotations.
  • Naming convention: SCREAMING_SNAKE_CASE.

2.5.2 Statics

Statics are similar to constants but represent a fixed location in memory.

static GREETING: &str = "Hello, world!";

fn main() {
    println!("{}", GREETING);
}

2.5.3 Comparison with C

In C, you use #define or const for constants.

#define MAX_POINTS 100000
const int max_points = 100000;
  • #define is a preprocessor directive; no type safety.
  • const variables can have type annotations.