C#LINK

MaybeHC

发布于 2024-04-23 18:23:39

590

发布于 2024-04-23 18:23:39

group子句

 var students = new[]
            {
                new {LName="Jones",FName="Mary",Age=23, Major="History"},
                new {LName="Smith",FName="Bob",Age=20, Major="Comsci"},
                new {LName="Fleming",FName="Carol",Age=21, Major="History"}
            };
            //var query = from student in students
            //            orderby student.Age
            //            select student.LName;
            var query = from student in students
                        group student by student.Major;

            foreach(var a in query)
            {
                Console.WriteLine("{0}",a.Key);//a.Key分组键
                foreach(var t in a)
                    Console.WriteLine("      {0},{1}",t.LName,t.FName);
            }
            Console.ReadKey();

let子句 let子句接受一个表达式的运算并且把它赋值给一个需要在其他运算中使用的标识符。

            var groupA = new[] { 3, 4, 5, 6 };
            var groupB = new[] { 6, 7, 8, 9 };
            var someInts = from a in groupA
                           from b in groupB
                           let num = a + b
                           where num >= 11
                           where a != 4
                           select new { a, b, num };
            foreach (var a in someInts)
            {
                Console.WriteLine(a);
            }
            Console.ReadKey();