Question

Purpose: To have multiple options to sort using properties of my class .
I managed to sort using samAccountName using Comparable but failed to correctly implement IComparer. But know I am getting an error specified below.

Error:Does not implement interface member System.Collections.Icomparer

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace ActiveDirectory
{
    public class sortLastName : IComparer
    {
        int IComparer.CompareTo(Employee oEmployee, Employee oEmployee2)
        {
            return String.Compare(oEmployee.lastName, oEmployee2.lastName);
        }
        public static IComparer sortYearAscending()
        {
            return (IComparer)new sortLastName();
        }

    }
//The code works great when I make a call like 
// List<Employee> x = new List<Employee>();
// x.sort();// sorts by samAccountName
// Now I would like to figure out how to sort by lastName and still be able to sort by 
//samAccountName if necceaary. 
    public class Employee :IComparable
    {
        //default sort order
        public int CompareTo(object oEmployee)
        {
            Employee emp1 = (Employee)oEmployee;
            return String.Compare(this.samAccountName, emp1.samAccountName);
        }



        public string lastName
        {
            get;
            set;

        }

          public string samAccountName
        {
            get;
            set;
        }
    }
}

Answer 1

you need to implement a method named “Compare” not “CompareTo” for your sortLastName-class implementing IComparer

then you can sort by x.Sort with this overload:

x.Sort(new sortLastName());

this is the implementation you should use:

public class sortLastName : IComparer<Employee>
{
    public int Compare(Employee oEmployee, Employee oEmployee2)
    {
        return String.Compare(oEmployee.lastName, oEmployee2.lastName);
    }
}

(Note I didn’t change the name because you wouldn’t see the context any more but sortLastName is no good name for a comparer)