Returning values from async methods in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the return type of an async method that returns a value in C#?

The return type is Task<T>, where T is the type of the value returned. For example, async Task<int> returns an integer asynchronously.

beginner

How do you return a value from an async method?

Use the return keyword followed by the value inside the async method. The value will be wrapped automatically in a Task<T>.

beginner

What keyword do you use to wait for the result of an async method that returns a value?

You use the await keyword to wait for the completion of the async method and get its returned value.

intermediate

Can an async method return void?

Yes, but only for event handlers. Normally, async methods should return Task or Task<T> to allow callers to await them and handle exceptions.

intermediate

What happens if you return a value directly from an async method without wrapping it in a Task?

You cannot return a value directly without wrapping it in Task<T>. The compiler requires async methods to return Task, Task<T>, or void.

What is the correct return type for an async method that returns a string?

A void

B string

C Task<string>

D Task

Async methods that return a value must return Task, where T is the value type. Here, it's Task.

Which keyword do you use to get the result from an async method?

A await

B yield

C async

D return

The 'await' keyword pauses execution until the async method completes and returns its value.

What is the return type of an async method that does not return a value?

A Task

B void

C Task<void>

D int

Async methods that do not return a value should return Task, not void, except for event handlers.

Can you use 'await' inside a method that is not marked async?

A Yes, always

B No, the method must be async

C Only if the method returns void

D Only in constructors

The 'await' keyword can only be used inside methods marked with the async modifier.

What happens if you forget to await an async method that returns a value?

A The value is returned immediately

B The method runs synchronously

C The program crashes

D You get the Task object instead of the value

If you don't await, you get the Task object, not the actual result value.

Explain how to write an async method that returns an integer value and how to get that value when calling the method.

Think about the method signature and how to wait for the result.

Describe the difference between async methods returning Task, Task, and void.

Consider how each return type affects calling and error handling.