async await in c#

 Async methods can have the following return types:

Task, for an async method that performs an operation but returns no value.

Task<TResult>, for an async method that returns a value.

void, for an event handler.

Task return type

Async methods that don't contain a return statement or that contain a return statement that doesn't return an operand usually have a return type of Task. Such methods return void if they run synchronously. If you use a Task return type for an async method, a calling method can use an await operator to suspend the caller's completion until the called async method has finished.

Example:

In the following example, the WaitAndApologizeAsync method doesn't contain a return statement, so the method returns a Task object. Returning a Task enables WaitAndApologizeAsync to be awaited. The Task type doesn't include a Result property because it has no return value.

public static async Task DisplayCurrentInfoAsync() { await WaitAndApologizeAsync(); Console.WriteLine($"Today is {DateTime.Now:D}"); Console.WriteLine($"The current time is {DateTime.Now.TimeOfDay:t}"); Console.WriteLine("The current temperature is 76 degrees."); } static async Task WaitAndApologizeAsync() { await Task.Delay(2000); Console.WriteLine("Sorry for the delay...\n"); }

Task<TResult> return type The Task<TResult> return type is used for an async method that contains

a return statement in which the operand is TResult. In the following example, the GetLeisureHoursAsync method contains a

return statement that returns an integer. Therefore, the method

declaration must specify a return type of Task<int>. The FromResult async

method is a placeholder for an operation that returns a DayOfWeek.

public static async Task ShowTodaysInfoAsync() { string message = $"Today is {DateTime.Today:D}\n" + "Today's hours of leisure: " + $"{await GetLeisureHoursAsync()}"; Console.WriteLine(message); } static async Task<int> GetLeisureHoursAsync() { DayOfWeek today = await Task.FromResult(DateTime.Now.DayOfWeek); int leisureHours = today is DayOfWeek.Saturday || today is DayOfWeek.Sunday ? 16 : 5; return leisureHours; }