Difference Between Async and Await in C# with Example – C# asynchronous programming 2024

Introduction (Difference Between Async and Await in C# asynchronous programming)

In this blog post, we’ll dive into the difference between async and await in C#, using practical examples to illustrate their usage.

In the world of modern programming, especially with the ever-growing importance of performance and responsiveness in applications, understanding asynchronous programming is crucial. The keywords “async” and “await” in C# are integral to this paradigm. We’ll explore how these keywords function, their benefits, and common pitfalls. By the end of this post, you’ll have a clear understanding of how to use async and await effectively in your C# applications.

What is Asynchronous Programming?

Asynchronous programming allows your program to initiate potentially long-running operations (such as file I/O, network requests, or database operations) and continue executing other tasks without waiting for the operation to complete. This can lead to more responsive applications, particularly in scenarios where the main thread must remain active and responsive to user interactions.

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When to Use Asynchronous Programming in C#

Asynchronous programming can significantly enhance the performance and responsiveness of your applications. Here are some scenarios where using async and await in C# is particularly beneficial:

  • I/O-Bound Operations:
    • File I/O: Reading from or writing to files, especially large ones.
    • Network Calls: Making web requests or consuming APIs.
    • Database Operations: Executing database queries or commands.
  • UI Applications:
    • Responsiveness: Keeping the UI responsive during long-running operations, such as loading data or processing user inputs.
    • Event Handling: Handling events without blocking the main thread.
  • Concurrent Tasks:
    • Parallel Processing: Running multiple independent tasks simultaneously, such as processing a batch of images or performing calculations.
  • Background Operations:
    • Timers and Delays: Implementing delays or periodic tasks without blocking the main thread.
    • Background Services: Running background tasks in web applications, such as sending emails or generating reports.

Benefits of Using Asynchronous Programming

  • Improved Performance: Non-blocking operations free up the main thread, allowing the application to handle more tasks concurrently.
  • Better Resource Utilization: Efficiently uses system resources by not keeping threads idle while waiting for I/O operations to complete.
  • Enhanced User Experience: Maintains responsiveness in UI applications, preventing freezing or lagging.

Understanding Async and Await

The Async Keyword

declare a method as asynchronous by using of async keyword. This means the method can run asynchronously, which allows the calling code to continue execution without waiting for the method to finish. An async method typically contains one or more await expressions that represent points at which the method can pause its execution until the awaited task completes.

Here’s a simple example:

Difference Between Async and Await in C# with Example
Difference Between Async and Await in C# with Example

In this example, GetDataFromServerAsync is an asynchronous method that simulates a network operation by waiting for 2 seconds. The method is marked with the async keyword, indicating it contains asynchronous operations.

Let’s see how to use Await Keyword

The await keyword is used within an async method to suspend the execution of the method until the awaited task completes. It allows other operations to run while waiting for the task to finish, making the application more efficient and responsive.

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Using the previous example, let’s see how await works:

Difference Between Async and Await in C#
Difference Between Async and Await in C#

In this method, UseDataAsync, the await keyword is used to wait for GetDataFromServerAsync to complete. While waiting, other code can continue to run. Once GetDataFromServerAsync finishes, the execution of UseDataAsync resumes with the result of the awaited task.

Detailed Example: Async and Await in Action

To better understand the difference between async and await in C#, let’s consider a more comprehensive example involving file I/O operations.

Step-by-Step Example

  1. Creating an Asynchronous Method for Reading a File
Async and Await in C#
Async and Await in C#

In this method, ReadFileAsync, we use await to wait for the completion of the ReadToEndAsync method, which reads the file contents asynchronously. The async keyword indicates that ReadFileAsync is an asynchronous method.

  1. Using the Asynchronous Method
C# Async and Await
C# Async and Await

In ProcessFileAsync, we call ReadFileAsync and use await to wait for its completion. This allows ProcessFileAsync to be paused while ReadFileAsync reads the file, without blocking other operations.

Running Asynchronous Methods

To run asynchronous methods, you typically use an async method at a higher level in your application. For example, in a console application, you might call your asynchronous methods from the Main method.

Async await in c#
Async await in c#

Error Handling in Async Methods

Error handling in asynchronous methods is done using try-catch blocks, similar to synchronous code. However, because asynchronous methods often return Task or Task<T>, you can also handle exceptions using the task’s Exception property.

async and await in c# .net core
async and await in c# .Net Core

In this method, if an error occurs during the execution of ReadFileAsync, it will be caught by the try-catch block, and an appropriate message will be printed.

While code use design patterns in c#.

Benefits of Using Async and Await

As per my experience so far by using async and await there are several benefits of using async and await in c#

  1. Improved Responsiveness: Asynchronous methods allow your application to remain responsive to user input while performing long-running operations.
  2. Efficient Resource Utilization: By not blocking threads, async methods make better use of system resources, allowing other tasks to run concurrently.
  3. Simplified Code: Using async and await makes your code easier to read and maintain compared to traditional asynchronous programming patterns like callbacks or manual thread management.

Common Pitfalls and Best Practices

Avoid Blocking Calls

Using blocking calls like Task.Wait() or Task.Result in asynchronous methods can negate the benefits of async programming and lead to deadlocks. Always use await instead.

Use ConfigureAwait in c#

When writing library code, consider using ConfigureAwait(false) to avoid capturing the synchronization context, which can lead to performance improvements.

Configureawait false in c#
Configureawait false in c#

Handle Exceptions

Always handle exceptions in async methods to prevent unhandled exceptions that can crash your application. Use try-catch blocks or the Task.Exception property.

Avoid Async Void

Except for event handlers, avoid using async void methods as they can’t be awaited and don’t provide a way to handle exceptions.

Conclusion

Understanding the difference between async and await in C# is crucial for writing efficient and responsive applications. The async keyword declares an asynchronous method, while the await keyword pauses the method’s execution until the awaited task completes. By using these keywords effectively, you can improve your application’s performance and responsiveness. Remember to follow best practices to avoid common pitfalls and ensure your code is robust and maintainable.

Async and await are powerful tools in C# that, when used correctly, can greatly enhance your application’s ability to handle long-running operations seamlessly. With the knowledge and examples provided in this blog post, you’re now equipped to implement asynchronous programming in your own C# projects.


By focusing on the difference between async and await in C#, and using practical examples, we’ve covered the fundamental aspects of these keywords. Implementing async and await effectively will enable you to build more responsive and efficient applications. Happy coding!

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