Bagaimana untuk menggunakan perintah mengikut dan kumpulan mengikut dalam C#?

Order by digunakan untuk mengisih tatasusunan dalam tertib menaik atau menurun

Operator GroupBy tergolong dalam kategori Operator Pengelompokan. Pengendali ini mengambil urutan item yang rata, menyusun urutan itu ke dalam kumpulan (IGrouping) berdasarkan kunci tertentu dan kumpulan kembalikan urutan

Contoh

class ElectronicGoods {
   public int Id { get; set; }
   public string Name { get; set; }
   public string Category { get; set; }
   public static List<ElectronicGoods> GetElectronicItems() {
      return new List<ElectronicGoods>() {
         new ElectronicGoods { Id = 1, Name = "Mobile", Category = "Phone"},
         new ElectronicGoods { Id = 2, Name = "LandLine", Category = "Phone"},
         new ElectronicGoods { Id = 3, Name = "Television", Category = "TV"},
         new ElectronicGoods { Id = 4, Name = "Grinder", Category = "Food"},
         new ElectronicGoods { Id = 5, Name = "Mixer", Category = "Food"},
      };
   }
}
class Program {
   static void Main() {
      //Group by
      var res=ElectronicGoods.GetElectronicItems().GroupBy(x => x.Category).Select(x => new {
         Key = x.Key,
         electronicGoods = x.OrderBy(c => c.Name)
      });
      foreach (var group in res) {
         Console.WriteLine("{0} - {1}", group.Key, group.electronicGoods.Count());
         Console.WriteLine("----------");
         foreach (var electronicGoods in group.electronicGoods) {
            Console.WriteLine(electronicGoods.Name + "\t" + electronicGoods.Category);
         }
         Console.WriteLine(); Console.WriteLine();
      }
      Console.ReadKey();
   }
}

Output

Phone - 2
----------
LandLine Phone
Mobile Phone
TV - 1
----------
Television TV
Food - 2
----------
Grinder Food
Mixer Food

Pesanan Oleh

的纻：译按顺序排列

class ElectronicGoods {
   public int Id { get; set; }
   public string Name { get; set; }
   public string Category { get; set; }
   public static List<ElectronicGoods> GetElectronicItems() {
      return new List<ElectronicGoods>() {
         new ElectronicGoods { Id = 1, Name = "Mobile", Category = "Phone"},
         new ElectronicGoods { Id = 2, Name = "LandLine", Category = "Phone"},
         new ElectronicGoods { Id = 3, Name = "Television", Category = "TV"},
         new ElectronicGoods { Id = 4, Name = "Grinder", Category = "Food"},
         new ElectronicGoods { Id = 5, Name = "Mixer", Category = "Food"},
      };
   }
}
class Program {
   static void Main() {
      //Order by
      var res = ElectronicGoods.GetElectronicItems().OrderBy(x => x.Category);
      foreach (var items in res) {
         Console.WriteLine(items.Name + "\t" + items.Category);
      }
      Console.ReadKey();
   }
}

Output

Grinder Food
Mixer Food
Mobile Phone
LandLine Phone
Television TV

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