在哪里以及如何放置等待关键字

Question

我想了解异步如何工作。这是我的代码：

class Program 
{ 
    static void Main(string[] args) 
    { 
     Task<string> strReturned = returnStringAsync(); 
     Console.WriteLine("hello!"); 
     string name = await strReturned; //error: The 'await' operator can only be used 
             //within an async method. Consider marking this 
             //method with the 'async' modifier and changing 
             //its return type to 'Task' 

     Console.WriteLine(name); 
    } 

    static async Task<string> returnStringAsync() 
    { 
     Thread.Sleep(5000); 
     return "Richard"; 
    } 
} 

是否有错误？

Answer 1

这工作

class Program 
{ 
    static void Main(string[] args) 
    { 
     Task<string> str = returnStringAsync(); 
     Console.WriteLine("hello!"); 

     string name = str.Result; 

     Console.WriteLine(name); 
    } 

    static async Task<string> returnStringAsync() 
    { 
     await Task.Delay(5000); 
     return "Richard"; 
    } 
}