How to sort a list of complex types using Comparison delegate in C#?

Overloads of the Sort() method in List class expects Comparison delegate to be passed as an argument.

public void Sort(Comparison<T> comparison)

CompareTo returns an integer that indicates whether the value of this instance is less than, equal to, or greater than the value of the specified object or the other Int16 instance.

The Int16.CompareTo() method in C# is used to compare this instance to a specified object or another Int16 instance

Example

class Program{
   public static void Main(){
      Employee Employee1 = new Employee(){
         ID = 101,
         Name = "Mark",
         Salary = 4000
      };
      Employee Employee2 = new Employee(){
         ID = 103,
         Name = "John",
         Salary = 7000
      };
      Employee Employee3 = new Employee(){
         ID = 102,
         Name = "Ken",
         Salary = 5500
      };
      List<Employee> listEmployees = new List<Employee>();
      listEmployees.Add(Employee1);
      listEmployees.Add(Employee2);
      listEmployees.Add(Employee3);
      Console.WriteLine("Employees before sorting");
      foreach (Employee Employee in listEmployees){
         Console.WriteLine(Employee.ID);
      }
      listEmployees.Sort((x, y) => x.ID.CompareTo(y.ID));
      Console.WriteLine("Employees after sorting by ID");
      foreach (Employee Employee in listEmployees){
         Console.WriteLine(Employee.ID);
      }
      listEmployees.Reverse();
      Console.WriteLine("Employees in descending order of ID");
      foreach (Employee Employee in listEmployees){
         Console.WriteLine(Employee.ID);
      }
   }
   // Approach 1 - Step 1
   // Method that contains the logic to compare Employees
   private static int CompareEmployees(Employee c1, Employee c2){
      return c1.ID.CompareTo(c2.ID);
   }
}
public class Employee{
   public int ID { get; set; }
   public string Name { get; set; }
   public int Salary { get; set; }
}

Output

Employees before sorting
101
103
102
Employees after sorting by ID
101
102
103
Employees in descending order of ID
103
102
101

Nizamuddin Siddiqui

Updated on 19-Aug-2020 13:32:43

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