Measure elapsed time

---

• std::time
• The Instant type allows us to get snapshots if time that can help us measure elapesd time.

• In this example we have a function to decide if a number is a prime number. We only use it to have some code that can take substantial time.
• We get the timestamp before and after and we calculate the elapsed time.

examples/datetime/instant-elapsed/src/main.rs

fn main() {
    let start = std::time::Instant::now();
    for number in 2..=100000 {
        let _prime = is_prime(number);
        //println!("{} {}", number, prime);
    }
    let end = std::time::Instant::now();

    println!("{:?}", start);
    println!("{:?}", end);
    let elapsed = end - start;
    println!("{:?}", elapsed);
    println!("{:?}", start.elapsed());
    println!("milliseconds: {:?}", start.elapsed().as_millis());
    println!("seconds:      {:?}", start.elapsed().as_secs());
}

fn is_prime(number: u32) -> bool {
    for div in 2..number {
        if number % div == 0 {
            return false;
        }
    }
    true
}

Instant { tv_sec: 5094523, tv_nsec: 863978009 }
Instant { tv_sec: 5094525, tv_nsec: 872085539 }
2.00810753s
2.008157397s
milliseconds: 2008
seconds:      2