Rust for C-Programmers

25.8 Mutable Global Variables

Global mutable variables in Rust are declared with static mut. They are inherently unsafe because concurrent or multi-path write access can lead to data races.

#![allow(unused)]
fn main() {
static mut COUNTER: i32 = 0;

fn increment() {
    unsafe {
        COUNTER += 1;
    }
}
}

It's best to minimize the use of mutable globals. When they are required, you should apply synchronization primitives to ensure safe, race-free access.