小白学Rust（一）：Rust产生随机数

先按本人教程如何利用科大源提速Cargo和Rust做好相关配置。然后在linux Bash下执行：

cargo new random --bin

这会在当前目录创建一个random文件夹，然后修改src下面的main.rs，代码如下：

extern crate rand;

use rand::Rng;

fn main(){
  let mut rng =rand::thread_rng();
  // Each thread has an automatically-initialised random number generator:

  // Integers are uniformly distributed over the type's whole range:

  let n1:u8 = rng.gen();
  let n2:u16 = rng.gen();
  println!("n1 is :{}",n1);
  println!("n2 is :{}",n2);
  println!("here is a random u32 number:{}",rng.gen::<u32>());
  println!("here is a random i32 number:{}",rng.gen::<i32>());

  // Floating point numbers are uniformly distributed in the half-open range [0, 1)
  println!("Random float: {}", rng.gen::<f64>());


  //Generates a random value within half-open [0, 10) range (not including 10) with Rng::gen_range.
  println!("Integer: {}", rng.gen_range(0, 10));
  println!("Float: {}", rng.gen_range(0.0, 10.0));



}

然后在Cargo.toml最后一行加入：

rand = "0.3.17"

执行cargo build和cargo run之后可以看到打印：

warning: custom registry support via the `registry.index` configuration is being removed, this functionality will not work in the future
   Compiling random v0.1.0 (file:///home/rustcode/basic/random)
    Finished dev [unoptimized + debuginfo] target(s) in 0.43 secs
     Running `target/debug/random`
n1 is :209
n2 is :28903
here is a random u32 number:867979277
here is a random i32 number:-2005811675
Random float: 0.0010826636175251814
Integer: 2
Float: 2.113870312229329

当然，这里用户可以自定义一个随机数生成方式，比如想要随机生成一个点的坐标：

extern crate rand;

use rand::{Rng,Rand};

#[derive(Debug)]
struct Point{
  x:i32,
  y:i32,
}
impl Rand for Point{
  fn rand<R:Rng>(rng:&mut R) -> Point{
  let (rand_x,rand_y) = rng.gen();
  Point{
  x:rand_x,
  y:rand_y,
    }


    }
}
fn main() {
 let mut rng = rand::thread_rng();
 let rand_tuple = rng.gen::<(i32, bool, f64)>();
 let rand_point: Point = rng.gen();
 println!("Random tuple: {:?}", rand_tuple);
 println!("Random Point: {:?}", rand_point);


}