fn main() {
    let mut values = [1, 2, 3, 4, 5];
    let ptr = values.as_mut_ptr();
    let len = values.len();
    let capacity = values.capacity();
 
    unsafe {
        for i in 0..len {
            *ptr.add(i) *= 2;
        }
        println!("Doubled via raw pointer: {:?}", values);
    }
 
    extern "C" {
        fn abs(input: i32) -> i32;
    }
 
    let negative = -42;
    let absolute = unsafe { abs(negative) };
    println!("Absolute value of {}: {}", negative, absolute);
 
    unsafe fn dangerous_operation() -> i32 {
        println!("This function is unsafe!");
        42
    }
 
    let result = unsafe { dangerous_operation() };
    println!("Unsafe function result: {}", result);
}