extern "C" {
fn abs(enter: i32) -> i32;
}
fn important() {
unsafe {
println!("Absolute worth of -3 in keeping with C: {}", abs(-3));
}
}
Any calls made to the capabilities uncovered by way of the extern "C" block should be wrapped in unsafe, the higher to make sure you take correct accountability for what you ship to it and get again from it.
Altering mutable static variables
World or static variables in Rust could be set to mutable, since they occupy a hard and fast reminiscence tackle. Nevertheless, it’s solely attainable to switch a mutable static variable inside an unsafe block.
Knowledge races are the most important motive you want unsafe to change mutable static variables. You’d get unpredictable outcomes in the event you allowed the identical mutable static variable to be modified from totally different threads. So, whereas you should use unsafe to make such adjustments, any information race points could be your accountability, not Rust’s. Usually, Rust can not completely forestall information races, however you might want to be doubly cautious about that in unsafe blocks.
