Three sorting methods for a set and three sorting methods for a set

Three sorting methods for a set and three sorting methods for a set

Sort the set by using the OrderBy method.

 

    class Program
    {
        static void Main(string[] args)
        {
            IEnumerable<Student> result = GetStudents().OrderBy(r => r.Score);
            foreach (var item in result)
            {
                Console.WriteLine(item.Name + "--" + item.Score);
            }
            Console.ReadKey();
        }
        private static List<Student> GetStudents()
        {
            return new List<Student>()
            {
New Student () {Id = 1, Name = "Zhang San", Age = 15, Score = 80 },
New Student () {Id = 2, Name = "", Age = 16, Score = 70 },
New Student () {Id = 3, Name = "Zhao Wu", Age = 14, Score = 90}
            };
        }
    }
    public class Student 
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public int Score { get; set; }
    }

 

Above, OrderBy returns IEnumerable <Student>.

 

If you want to use the Sort method of List <T>, You need to enable Student to implement the IComparable <Student> interface.

 

   class Program
    {
        static void Main(string[] args)
        {
            List<Student> result = GetStudents();
            result.Sort();
            foreach (var item in result)
            {
                Console.WriteLine(item.Name + "--" + item.Score);
            }
            Console.ReadKey();
        }
        private static List<Student> GetStudents()
        {
            return new List<Student>()
            {
New Student () {Id = 1, Name = "Zhang San", Age = 15, Score = 80 },
New Student () {Id = 2, Name = "", Age = 16, Score = 70 },
New Student () {Id = 3, Name = "Zhao Wu", Age = 14, Score = 90}
            };
        }
    }
    public class Student : IComparable<Student>
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public int Score { get; set; }
        
        public int CompareTo(Student other)
        {
          return  this.Score.CompareTo(other.Score);
        }
    }

 

It is good to make Student implement the IComparable <Student> interface. If Student is a sealed class, we cannot implement the IComparable <Student> interface? Don't worry. The Sort method provides an overload that can receive IComparer interface types.

 

   class Program
    {
        static void Main(string[] args)
        {
            List<Student> result = GetStudents();
            result.Sort(new StudentSorter());
            foreach (var item in result)
            {
                Console.WriteLine(item.Name + "--" + item.Score);
            }
            Console.ReadKey();
        }
        private static List<Student> GetStudents()
        {
            return new List<Student>()
            {
New Student () {Id = 1, Name = "Zhang San", Age = 15, Score = 80 },
New Student () {Id = 2, Name = "", Age = 16, Score = 70 },
New Student () {Id = 3, Name = "Zhao Wu", Age = 14, Score = 90}
            };
        }
    }
    public class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public int Score { get; set; }
    }
    public class StudentSorter : IComparer<Student>
    {
        public int Compare(Student x, Student y)
        {
            return x.Score.CompareTo(y.Score);
        }
    }

 

To sum up, there are three ways to sort a set:

 

1. Use the SortBy method to return the IEnumerable <T> type.
2. Let the collection element implement the IComparable <T> interface, and then use the Sort method to return void.
3. Set elements do not implement the IComparable <T> interface. Write a class that implements the IComparer <T> interface for the set element type and use the class instance as a parameter of the Sort method.