這個Linq查詢的等效C＃擴展方法是什麼？

Question

在this example:

public void Linq40() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 

    var numberGroups = 
     from n in numbers 
     group n by n % 5 into g 
     select new { Remainder = g.Key, Numbers = g }; 

    foreach (var g in numberGroups) 
    { 
     Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", 
      g.Remainder); 

     foreach (var n in g.Numbers) 
     { 
      Console.WriteLine(n); 
     } 
    } 
} 

什麼是純C＃相同呢？我得到這個...

var numberGroups = numbers.GroupBy(n => n % 5)... 

但into子句是一個有點神祕，我無法弄清楚如何從Select得到Key。

Answer 1

GroupBy返回<IGrouping<TKey, TSource>的IEnumerable<T>。有了這個，你可以做第二次選擇操作，它返回如上完全一樣的值：

var numberGroups = numbers.GroupBy(n => n % 5) 
          .Select(g => new { Remainder = g.Key, Numbers = g }); 

Answer 2

numbers.GroupBy(n => n % 5).Select(g => new { Remainder = g.Key, Numbers = g });