IComparer problem

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, oEmploye开发者_StackOverflow社区e2.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;
        }
    }
}

---

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)

---

I have absolutely no idea what your IComparer implementation is for.

You should probably implement IComparable<T> instead of non-generic IComparable, but whatever.

Either way, incorporate the sort order you want into your CompareTo function. For example:

public int CompareTo(object oEmployee)
{
    Employee e = (Employee)oEmployee;
    int cmp = 0;
    if ((cmp = string.Compare(this.samAccountName, e.samAccountName) != 0)
        return cmp;
    if ((cmp = string.Compare(this.lastName, e.lastName) != 0)
        return cmp;

    // ...any other properties you care to compare by

    // else it's a tie:
    return cmp;
}

Then this should work correctly with List<T>.Sort, since the default comparer will look for an implementation of IComparable on your type.

EDIT: On a re-read, I'm not sure whether you want to sort by one criteria, the other, or both. But I'll leave this answer in for posterity in case you want to sort by both.

---

IComparer. Compare takes two object as argument. You don't use that signature in class sortLastName. There also is a generic version, if that's the interface You want...

IComparer : http://msdn.microsoft.com/en-us/library/system.collections.icomparer.compare(v=vs.71).aspx

---

You dont need IComparer or IComparable to achieve this at all.

List<Employee> sortedByLastname = lstEmployee.OrderBy(x => x.LastName);

---

Implementation: //suppose that this fill out the list with employees. //After your suggestions this is what I ended up doing.

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            populatecboAdUsers();
        }
public void populatecboAdUsers()
        {
            List oEmployee = manager.getAllEmployees();
            //oEmployee.Sort();//uses the default compare by samAccountName

            IComparer myComparer = new Employee.compareEmployeeByLastName();
            oEmployee.Sort(myComparer.Compare);
            foreach (var x in oEmployee)
            {

                cboAdUsers.Items.Add(x.lastname);
                Console.WriteLine(x.lastname);

       }
}//end of Form1:form class

//new class below
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;


namespace ActiveDirectory
{


    public class Employee :IComparable
    {
        public class compareEmployeeByLastName : IComparer
        {
            int IComparer.Compare(object x, object y)
            {
                Employee emp1 = (Employee)x;
                Employee emp2 = (Employee)y;
                return String.Compare(emp1.lastname, emp2.lastname);
            }
        }
        //default sort order
        public int CompareTo(object oEmployee)
        {
            Employee emp1 = (Employee)oEmployee;
            return String.Compare(this.samAccountName, emp1.samAccountName);
        }


        public string firstName 
        { 
            get; set; 
        }

        public string lastName
        {
            get;
            set;

        }

        public string commonName
        {
            get;
            set;
        }

        public string department
        {
            get;
            set;
        }

        public string distinguishedName
        {
            get;
            set;
        }

        public string employeeID
        {
            get;
            set;
        }

        public string samAccountName
        {
            get;
            set;
        }

        public string email
        {
            get;
            set;
        }

        public string title
        {
            get;
            set;
        }

        public UserPrincipalExtension oUserPrincipalExtension
        {
            get;
            set;
        }
    }



}