TcpClient.ConnectAsync Methode async / await / Task

Question

How can I call an async function from a standard function?

What do I have to do? What is the syntax?

The await does that.

The function waits for feedback, but is processed asynchronously.

A UserInterface does not hang then, is further operable?

With or without 'await' nothing goes. Why?

public static int Main(String[] args)
{
	// here is not async
	Test();
	return 0;
}


public static async Task Test()
{
// here is async
	using (TcpClient tcp = new TcpClient())
	{
		IAsyncResult ar = tcp.BeginConnect("127.0.0.1", 6000, null, null);
		System.Threading.WaitHandle wh = ar.AsyncWaitHandle;
		try
		{
			if (!ar.AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(15), true))
			{
				tcp.Close();
				throw new TimeoutException();
			}

			tcp.EndConnect(ar);
		}
		finally
		{
			wh.Close();

async

Answer 1

What version of C# are you using? In later versions (7.1+) of C# Main can be async so you can await inside Main just like you would anywhere else.

public static async Task<int> Main(String[] args)
{
   await Test();
   return 0;
}

For other synchronous methods then you can use a hack.

void SomeSyncMethod ()
{
   //Block until done
   Test().GetAwaiter().GetResult();
   //Alternative version but it doesn't propagate exceptions the same
   //Test().Wait();
}

But this is generally not recommended as it can cause issues depending upon how this method is being called. So use it only when you absolutely must.

Answer 2

@Michael Taylor , Welcome to Microsoft Q&A, you could try the following code to call an async function from a standard function.

In console app, you could call it in main method like the following:

 static async Task Main(string[] args)
        {
            await Test();
        }

In winform app, you could call it in button_click event like the following:

 private async void button2_Click(object sender, EventArgs e)
        {
            await Test();
        }

Hope my code could help you.

Best Regards,

Jack

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