Class with IComparable and IComparer : IComparer « Data Structure « C# / CSharp Tutorial

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

using System;
using System.Collections;

public class MainClass
{
  public static int Main(string[] args)
  {
    Employee[] empList = new Employee[5];

    empList[0] = new Employee(123, "R");
    empList[1] = new Employee(6, "M");
    empList[2] = new Employee(6, "V");
    empList[3] = new Employee(13, "N");
    empList[4] = new Employee(6, "C");

    if(empList[0] < empList[4])
      Console.WriteLine("empList[0] < empList[4]");
    else
      Console.WriteLine("empList[0] >= empList[4]");
  
    return 0;
  }
}
public class Employee : IComparable
{
  private class SortByEmployeemNameHelper : IComparer
  {
    public SortByEmployeemNameHelper(){}
    int IComparer.Compare(object o1, object o2)
    {
      Employee t1 = (Employee)o1;
      Employee t2 = (Employee)o2;
      return String.Compare(t1.EmployeemName, t2.EmployeemName);
    }
  }

  private int EmployeeID;
  private string petName;

  // properties.
  public int ID
  {
    get{return EmployeeID;}
    set{EmployeeID = value;}
  }
  public string EmployeemName
  {
    get{return petName;}
    set{petName = value;}
  }

  // Constructor set.
  public Employee(){}
  public Employee(int id, string name){ 
      this.EmployeeID = id; 
      this.petName = name;
  }

  // IComparable implementation.
  int IComparable.CompareTo(object o)
  {
    Employee temp = (Employee)o;
    if(this.EmployeeID > temp.EmployeeID)
      return 1;
    if(this.EmployeeID < temp.EmployeeID)
      return -1;
    else
      return 0;
  }

  // Property to return the SortByEmployeemName comparer.
  public static IComparer SortByEmployeemName{ 
      get { return (IComparer)new SortByEmployeemNameHelper(); } 
  }

  public static bool operator < (Employee c1, Employee c2)
  {
    IComparable itfComp = (IComparable)c1;
    return (itfComp.CompareTo(c2) < 0);
  }

  public static bool operator > (Employee c1, Employee c2)
  {
    IComparable itfComp = (IComparable)c1;
    return (itfComp.CompareTo(c2) > 0);
  }

  public static bool operator <= (Employee c1, Employee c2)
  {
    IComparable itfComp = (IComparable)c1;
    return (itfComp.CompareTo(c2) <= 0);
  }

  public static bool operator >= (Employee c1, Employee c2)
  {
    IComparable itfComp = (IComparable)c1;
    return (itfComp.CompareTo(c2) >= 0);
  }
}

empList[0] >= empList[4]