首页 > 代码库 > An entry point cannot be marked with the 'async' modifier

An entry point cannot be marked with the 'async' modifier

2024-09-14 17:32:17   207人阅读

I copied below code from this link.But when I am compiling this code I am getting an entry point cannot be marked with the ‘async‘ modifier. How can I make this code compilable?

class Program{    static async void Main(string[] args)    {        Task<string> getWebPageTask = GetWebPageAsync("http://msdn.microsoft.com");        Debug.WriteLine("In startButton_Click before await");        string webText = await getWebPageTask;        Debug.WriteLine("Characters received: " + webText.Length.ToString());     }    private static async Task<string> GetWebPageAsync(string url)    {        // Start an async task.         Task<string> getStringTask = (new HttpClient()).GetStringAsync(url);        // Await the task. This is what happens:         // 1. Execution immediately returns to the calling method, returning a         //    different task from the task created in the previous statement.         //    Execution in this method is suspended.         // 2. When the task created in the previous statement completes, the         //    result from the GetStringAsync method is produced by the Await         //    statement, and execution continues within this method.         Debug.WriteLine("In GetWebPageAsync before await");        string webText = await getStringTask;        Debug.WriteLine("In GetWebPageAsync after await");        return webText;    }    // Output:     //   In GetWebPageAsync before await     //   In startButton_Click before await     //   In GetWebPageAsync after await     //   Characters received: 44306}

The error message is exactly right: the Main() method cannot be async, because when Main()returns, the application usually ends.

If you want to make a console application that uses async, a simple solution is to create an asyncversion of Main() and synchronously Wait() on that from the real Main():

static void Main(){    MainAsync().Wait();}static async Task MainAsync(){    // your async code here}

This is one of the rare cases where mixing await and Wait() is a good idea, you shouldn‘t usually do that.

 

from:http://stackoverflow.com/questions/16712172/an-entry-point-cannot-be-marked-with-the-async-modifier

from:http://www.itstrike.cn/Question/f33637bc-2f7f-47b3-9985-0fe709b24d57.html

 

28down votefavorite
5

I copied below code from this link.But when I am compiling this code I am getting an entry point cannot be marked with the ‘async‘ modifier. How can I make this code compilable?

classProgram{static async voidMain(string[] args){Task<string> getWebPageTask =GetWebPageAsync("http://msdn.microsoft.com");Debug.WriteLine("In startButton_Click before await");string webText = await getWebPageTask;Debug.WriteLine("Characters received: "+ webText.Length.ToString());}privatestatic async Task<string>GetWebPageAsync(string url){// Start an async task. Task<string> getStringTask =(newHttpClient()).GetStringAsync(url);// Await the task. This is what happens: // 1. Execution immediately returns to the calling method, returning a //    different task from the task created in the previous statement. //    Execution in this method is suspended. // 2. When the task created in the previous statement completes, the //    result from the GetStringAsync method is produced by the Await //    statement, and execution continues within this method. Debug.WriteLine("In GetWebPageAsync before await");string webText = await getStringTask;Debug.WriteLine("In GetWebPageAsync after await");return webText;}// Output: //   In GetWebPageAsync before await //   In startButton_Click before await //   In GetWebPageAsync after await //   Characters received: 44306}
c# async-await c#-5.0

An entry point cannot be marked with the 'async' modifier


联系
我们