Run time error and Program exits when using - Async and await using C#

Question

I am trying to use the concept of async and await in my program. The program abruptly exits. I am trying to get the content length from few random urls and process it and display the size in bytes of each url.

Code:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;

namespace TestProgram
{
    public class asyncclass
    {

        public async void  MainCall() {

             await SumPageSizes();

        }

        public async Task SumPageSizes(){

            List<string> urllist = GetUrlList();

            foreach (var url in urllist)
            {
                byte[] content = await GetContent(url);
                Displayurl(content, url);

            }


        }

        private void Displayurl(byte[] content, string url)
        {
            var length = content.Length;
            Console.WriteLine("The bytes length for the url response " + url + " is of :" +length );
        }

        private async Task<byte[]> GetContent(string url)
        {
            var content = new MemoryStream();

            try
            {


                var obj = (HttpWebRequest)WebRequest.Create(url);

                WebResponse response = obj.GetResponse();
                using (Stream stream = response.GetResponseStream())
                {
                    await stream.CopyToAsync(content);

                }


            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.StackTrace);

            }

            return content.ToArray();
        }

        private List<string> GetUrlList()
        {
            var urllist = new List<string>(){
                "http://msdn.microsoft.com/library/windows/apps/br211380.aspx",
                "http://msdn.microsoft.com",
                "http://msdn.microsoft.com/en-us/library/hh290136.aspx",
                "http://msdn.microsoft.com/en-us/library/ee256749.aspx",
                "http://msdn.microsoft.com/en-us/library/hh290138.aspx",
                "http://msdn.microsoft.com/en-us/library/hh290140.aspx",
                "http://msdn.microsoft.com/en-us/library/dd470362.aspx",
                "http://msdn.microsoft.com/en-us/library/aa578028.aspx",
                "http://msdn.microsoft.com/en-us/library/ms404677.aspx",
                "http://msdn.microsoft.com/en-us/library/ff730837.aspx"
            };
            return urllist;
        }
    }
}

Main

 public static void Main(string[] args)
        {
            asyncclass asyncdemo = new asyncclass();
            asyncdemo.MainCall();

        }

Answer 1

MainCall returns an uncompleted task and no other line of code is present beyond that, so your program ends

To wait for it use:

asyncdemo.MainCall().Wait();

You need to avoid async void and change MainCall to async Task in order to be able to wait for it from the caller.

Since this seems to be a console application, you can't use the await and async for the Main method using the current version of the compiler (I think the feature is being discussed for upcoming implementation in C# 7).