Rust random number

from-linux.rs

use std::fs::File;
use std::io::Read;

fn main() {
  let mut f = File::open("/dev/urandom").unwrap(); // from Linux
  let mut buf = [0u8; 16];
  f.read_exact(&mut buf).unwrap();

  println!("{:?}", buf);
}

getrandom-crate.rs

fn main() {
    println!("{:?}", get_random_buf());
}

fn get_random_buf() -> Result<[u8; 32], getrandom::Error> {
    let mut buf = [0u8; 32];
    getrandom::getrandom(&mut buf)?;
    Ok(buf)
}

no-dependency.rs

fn main() {
    unsafe {
        srand();
        println!("{}", rand());
    }
}
  
extern "C" {
    fn srand() -> u32;
    fn rand() -> u32;
}