Rust : time,关于程序运行的计时

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/wowotuo/article/details/81813603

一、系统自带的包，time
有两种方式：都可以；缺点是，目前只有as_secs().
目前 as_millis() 还处于nightly阶段，后续才会推出。

use std::time::{Duration, SystemTime};
fn fib(x: i64) -> i64 {
    match x <2{
        true => x,
        _ => fib(x - 2) + fib(x - 1),
    }
}
fn main() {
    let nums:Vec<i64> = vec![30_i64,35,40,45];
    for n in nums {
        let sy_time = SystemTime::now();
        let value = fib(n);
        println!("{:?},{:?}", SystemTime::now().duration_since(sy_time).unwrap().as_secs(),value);
        println!("{:?},{:?}", sy_time.elapsed().unwrap().as_secs(),value);
    }
    thread::sleep_ms(500000);
}

二、外部的包，stopwatch=”0.0.7”

优点：精度高。

extern crate stopwatch;
use stopwatch::{Stopwatch};

fn fib(x: i64) -> i64 {
    match x <2{
        true => x,
        _ => fib(x - 2) + fib(x - 1),
    }
}

fn main() {
    let nums:Vec<i64> = vec![30_i64,35,40,45];
    for n in nums {
        let sw = Stopwatch::start_new();
        let value = fib(n);
        println!("n:{0} recur value :{1} It took {2:.8} ms",n,value,sw.elapsed_ms());
    }