Use async await on c# 🚀 (easy way)

#csharp #tutorial #programming #dotnet

Do you want to use async/await on c# ? (yes, as in javascript) Okey, I'll show you how to do that in an easy way 😎

First of all

You should have your project on c# (.net core/framework) created.

Let's start

There are a few concepts that you need to know, so this tutorial is divided into several small sections:

Task class 🧙 your best friend

The task class on c# represents an async operation, this operation can be a simple method wich will be called without interrupt the current process thread, it'll run on another Thread, but you don't have to do any complex syntax, just call a method.

This is the basic usage:

We can see, 3 elements:

The Task class constructor and variable task1
A lambda expression (is like an arrow function): that represent the operation wich we want to run (lambda expression in c#).
Start method call: run the operation asynchronously

Output:

Hello! this will run async

A more detailed example 👀

The task class is a powerful tool of c#, but maybe you got confused on how and when it is running.

Well this is a more detailed example, we have 2 tasks to do:

As you can see, the 2 tasks are example operations wich use Thread.Sleep(miliseconds) function to stop temporaly the task thread (to simulate a real operation).

So, let's Start these tasks and check it's behaviour:

Output

Starting all tasks
Starting task 1
Starting task 2
------------------------------------
All tasks have finished, or not?
Task 1 done
Task 2 done

As we can see, the 2 tasks have been called asynchronously, and it's output is on the bottom.

But what happend with the All tasks have finished, or not? line, it should appear after tasks have been done, how can we do that? It's very easy, and we'll see it on the next section

Async/Await 🪄

Async/Await in c# is simple. You just have to put the async word in a method, example:
public void DoSomething() to public async void DoSomething().

Now, this method is able to "await" a Task until it finishes its work, using the await word before the task name 🤯

So, we can modify the example of the previous section to make it an async method:

As we can see, the code is inside of an async method called Main. Also, we add await task, this will allow us to control the code flow.

Now, the task 1 will start with task1.Start() normally, but the await task1 statement won't allow the code execution to continue until the task 1 has finished. The same behaviour for the task 2.

The output:

Starting all tasks

Hello! this will run async
Starting task 1
Task 1 done
Starting task 2
Task 2 done
------------------------------------
All tasks have finished, or not?

We have fixed the problems we saw in the previous section.

The line All tasks have finished, or not? is at the end
Also, both tasks run as a synchronous operation, but with the advantages of Async/Await features 💪