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  • c# order by 用法

    class OrderbySample1
    {
        static void Main()
        {            
            // Create a delicious data source.
            string[] fruits = { "cherry", "apple", "blueberry" };
    
            // Query for ascending sort.
            IEnumerable<string> sortAscendingQuery =
                from fruit in fruits
                orderby fruit //"ascending" is default
                select fruit;
    
            // Query for descending sort.
            IEnumerable<string> sortDescendingQuery =
                from w in fruits
                orderby w descending
                select w;            
    
            // Execute the query.
            Console.WriteLine("Ascending:");
            foreach (string s in sortAscendingQuery)
            {
                Console.WriteLine(s);
            }
    
            // Execute the query.
            Console.WriteLine(Environment.NewLine + "Descending:");
            foreach (string s in sortDescendingQuery)
            {
                Console.WriteLine(s);
            }
    
            // Keep the console window open in debug mode.
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }
    }
    /* Output:
    Ascending:
    apple
    blueberry
    cherry
    
    Descending:
    cherry
    blueberry
    apple
    */
    class OrderbySample2
    {
        // The element type of the data source.
        public class Student
        {
            public string First { get; set; }
            public string Last { get; set; }
            public int ID { get; set; }
        }
    
        public static List<Student> GetStudents()
        {
            // Use a collection initializer to create the data source. Note that each element
            //  in the list contains an inner sequence of scores.
            List<Student> students = new List<Student>
            {
               new Student {First="Svetlana", Last="Omelchenko", ID=111},
               new Student {First="Claire", Last="O'Donnell", ID=112},
               new Student {First="Sven", Last="Mortensen", ID=113},
               new Student {First="Cesar", Last="Garcia", ID=114},
               new Student {First="Debra", Last="Garcia", ID=115} 
            };
    
            return students;
    
        }
        static void Main(string[] args)
        {
            // Create the data source.
            List<Student> students = GetStudents();
    
            // Create the query.
            IEnumerable<Student> sortedStudents =
                from student in students
                orderby student.Last ascending, student.First ascending
                select student;
    
            // Execute the query.
            Console.WriteLine("sortedStudents:");
            foreach (Student student in sortedStudents)
                Console.WriteLine(student.Last + " " + student.First);           
    
            // Now create groups and sort the groups. The query first sorts the names
            // of all students so that they will be in alphabetical order after they are
            // grouped. The second orderby sorts the group keys in alpha order.            
            var sortedGroups =
                from student in students
                orderby student.Last, student.First
                group student by student.Last[0] into newGroup
                orderby newGroup.Key
                select newGroup;
    
            // Execute the query.
            Console.WriteLine(Environment.NewLine + "sortedGroups:");
            foreach (var studentGroup in sortedGroups)
            {
                Console.WriteLine(studentGroup.Key);
                foreach (var student in studentGroup)
                {
                    Console.WriteLine("   {0}, {1}", student.Last, student.First);
                }
            }
    
            // Keep the console window open in debug mode
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }
    }
    /* Output:  
    sortedStudents:
    Garcia Cesar
    Garcia Debra
    Mortensen Sven
    O'Donnell Claire
    Omelchenko Svetlana
    
    sortedGroups:
    G
       Garcia, Cesar
       Garcia, Debra
    M
       Mortensen, Sven
    O
       O'Donnell, Claire
       Omelchenko, Svetlana
    */
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  • 原文地址:https://www.cnblogs.com/hbsfgl/p/5024117.html
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