Define your own comparasion type and Comparer : IComparable « Data Structure « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Data Structure
3. IComparable

using System;
using System.Collections.Generic;

    public class Employee : IComparable<Employee>
    {
        private int empID;

        private int yearsOfSvc = 1;

        public Employee(int empID)
        {
            this.empID = empID;
        }

        public Employee(int empID, int yearsOfSvc)
        {
            this.empID = empID;
            this.yearsOfSvc = yearsOfSvc;
        }

        public override string ToString()
        {
            return "ID: " + empID.ToString() + ". Years of Svc: " + yearsOfSvc.ToString();
        }

        public bool Equals(Employee other) 
        {
            if (this.empID == other.empID)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        public static EmployeeComparer GetComparer()
        {
            return new Employee.EmployeeComparer();
        }

        public int CompareTo(Employee rhs)
        {
            return this.empID.CompareTo(rhs.empID);
        }

        public int CompareTo(Employee rhs,Employee.EmployeeComparer.ComparisonType which)
        {
            switch (which)
            {
                case Employee.EmployeeComparer.ComparisonType.EmpID:
                    return this.empID.CompareTo(rhs.empID);
                case Employee.EmployeeComparer.ComparisonType.Yrs:
                    return this.yearsOfSvc.CompareTo(rhs.yearsOfSvc);
            }
            return 0;

        }
        public class EmployeeComparer : IComparer<Employee>
        {
            public enum ComparisonType
            {
                EmpID,
                Yrs
            };

            public bool Equals(Employee lhs, Employee rhs)
            {
                return this.Compare(lhs, rhs) == 0;
            }

            public int GetHashCode(Employee e)
            {
                return e.GetHashCode();
            }
            public int Compare(Employee lhs, Employee rhs)
            {
                return lhs.CompareTo(rhs, EmpCompareType);
            }

            public Employee.EmployeeComparer.ComparisonType
                EmpCompareType {get; set;}
        }
    }
    public class Tester
    {
        static void Main()
        {
            List<Employee> empArray  = new List<Employee>();
            Random r = new Random();
            for (int i = 0; i < 5; i++)
            {
                empArray.Add(new Employee(r.Next(10) + 100, r.Next(20)));
            }
            Employee.EmployeeComparer c = Employee.GetComparer();
            c.EmpCompareType = Employee.EmployeeComparer.ComparisonType.EmpID;
            empArray.Sort(c);
            for (int i = 0; i < empArray.Count; i++)
            {
                Console.WriteLine(empArray[i].ToString());
            }
            c.EmpCompareType = Employee.EmployeeComparer.ComparisonType.Yrs;
            empArray.Sort(c);

            for (int i = 0; i < empArray.Count; i++)
            {
                Console.WriteLine(empArray[i].ToString());
            }
        }
    }