Exemplo de Async/Await C# 4.5

async await sample c# 4.5

using System;
using System.Threading.Tasks;

namespace Exemplo.AsyncAwait
{
    class Program
    {
        static void Main(string[] args)
        {
            Exec();
            Console.ReadLine();
        }

        static async void Exec()
        {
            var task = Task.Run(() => SayHelloAsync());
            Console.WriteLine(await task);
        }

        static async Task<string> SayHelloAsync()
        {
            return "Hello";
        }
    }
}