rust 代码片

允许无效代码和无效导入

#![allow(dead_code)]
#![allow(unused_imports)]
#![allow(unused_variables)]

随机数

[dependencies]
rand = "0.4"

extern crate rand;

use rand::Rng;
let mut rng = rand::thread_rng();
let x = rng.gen::<f32>();//x belong to [0,1)

秒表

use std::time::SystemTime;

let start_time = SystemTime::now();

//workload code

let end_time = SystemTime::now();
let difference = end_time.duration_since(start_time)
                         .expect("SystemTime::duration_since failed");
println!("{:?}", difference);

写文件

use std::io::prelude::*;
use std::fs::File;

let mut file = File::create("a.txt").expect("Cannot create file");
file.write_all(String::from("content").as_bytes()).expect("Cannot write file");
//file.write_all(b"content").expect("Cannot write file");

字符串编码

use encoding::{Encoding, DecoderTrap};
use encoding::all::WINDOWS_31J;
let mut model_name = [0u8; 10];
file.read(&mut model_name).unwrap();
let s = WINDOWS_31J.decode(&model_name, DecoderTrap::Ignore);

大小端

use byteorder::{LittleEndian, ReadBytesExt};
file.read_f32::<LittleEndian>().unwrap();

cpu核心数量
num_cpus