In C#, async
and await
are keywords used in asynchronous programming to simplify the process of executing long-running operations asynchronously without blocking the main thread.
async
is used to mark a method as an asynchronous method, which can perform long-running operations without blocking the calling thread. The method returns a Task or Task<T> object that represents the ongoing operation.
await
is used to indicate that the calling code should wait asynchronously for the completion of a Task<T> or Task operation. When the await keyword is encountered in the code, the compiler generates code that automatically schedules the continuation of the method after the asynchronous operation completes.
In simpler terms, async
is used to define a method as asynchronous, and await
is used to wait for the result of an asynchronous operation.
Here's an example:
csharpasync Task<string> GetDataAsync()
{
// perform some long-running operation
await Task.Delay(5000);
// wait for 5 seconds
return "data";
}
async Task DoSomethingAsync()
{
// call GetDataAsync and wait for the result
string data = await GetDataAsync();
// do something with the data
Console.WriteLine(data);
}
In this example, GetDataAsync
is marked as async
, which allows it to perform a long-running operation (in this case, a 5-second delay) without blocking the calling thread. The method returns a Task<string>
object that represents the ongoing operation.
DoSomethingAsync
is also marked as async
and calls GetDataAsync
using the await
keyword. The code after the await
statement is automatically scheduled to run after the completion of the asynchronous operation.
Note that the use of async
and await
can significantly simplify asynchronous programming, but it's important to use them correctly to avoid introducing bugs or performance issues in your code.
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