# Solved: elapsed time

Elapsed time is a critical aspect in many applicationsin software development. Whether you’re building a game, a time-tracking tool, or a productivity app, calculating elapsed time accurately and efficiently is crucial. In Rust, several methods allow developers to calculate elapsed time. This article will focus on the standard Rust solution, describing the problem, presenting the solution, and explaining each step of the code.

## Problem

Every developer at some point needs to calculate the time differencebetween two points in a program’s execution. The challenge is not merely measuring the time but ensuring that the measurement is accurate, precise, and efficient in terms of system resources.

## Solution using Rust’s Standard Library

In Rust, the standard library provides a way to calculate elapsed time by using the Instant struct from the std::time module.The following solution uses the Instant::now function, which returns an instance of the current point in time.

First step is to import the library:

use std::time::Instant;

The next step involves capturing the current time at some point in your code, storing that time, running your operations, then capturing the current time again.

let start = Instant::now();
// some operation
let duration = start.elapsed();

At this point, ‘duration’ holds the elapsed time.

## Step-by-step Explanation of the Code

In Rust, std::time::Instant::now method gives the current time as an Instant struct object. The returned object has two useful methods: “elapsed” and “duration_since”. The “elapsed” function, when called on an Instant object, gives the Duration between now and that Instant.

In the code provided, we first capture the time at the start of the operation and store this in the “start” variable. We then perform the operation. After, we use the elapsed method on the “start” Instant to get a Duration struct. This struct represents the elapsed time.

## Improving Accuracy

To improve the accuracy of elapsed time calculation, you should place the timer start and end as close to the operation as possible, literally the line before and after if you can.

Another point to note is Rust’s ability to manage system clock changes. Rust accounts for these automatically, so even if the system clock changes while your code is running, you’ll still get the correct elapsed time.

## Useful Libraries with Rust

Some handy libraries work with Rust for not only calculating elapsed time but also for date-time functionalities. These include:

• Chrono: This is a Rust date-time handling library providing types and functions necessary for time parsing, displaying, and arithmetic.
• Time: This library focuses on time manipulation, including finding the duration and calculating elapsed time.

Understanding how to work with elapsed time in your application is an excellent skill in the hands of any Rust developer. With the feature-rich standard libraries and useful third-party libraries at your disposal, you have all you need to handle almost every time-related task in your application.

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