IComparable,IComparer

public interface IComparable
{
int CompareTo(object o);
}


so
class Human
{
public string Name{get;set;}
public Human(string name)
{ Name = name; }
}
will change as
class Human : IComparer
{
public string Name { get; set; }
public Human(string name)
{ Name = name; }

int IComparer.Compare(object o1, object o2)
{
Human t1 = o1 as Human;
Human t2 = o2 as Human;
if (t1 != null && t2 != null)
return String.Compare(t1.Name, t2.Name);
else
throw new ArgumentException("Parameter is not a Human!");
}
}

Other ways of comparing
public class HumanNameComaparer : IComparer
{
// Test the pet name of each object.
int IComparer.Compare(object o1, object o2)
{
Human t1 = o1 as Human;
Human t2 = o2 as Human;
if (t1 != null && t2 != null)
return String.Compare(t1.Name, t2.Name);
else
throw new ArgumentException("Parameter is not a Human!");
}
}

public class HumanNameSizeComaparer : IComparer
{
// Test the pet name of each object.
int IComparer.Compare(object o1, object o2)
{
Human t1 = o1 as Human;
Human t2 = o2 as Human;
if (t1 != null && t2 != null)
return (t1.Name.Length>t2.Name.Length)? 1 : -1;
else
throw new ArgumentException("Parameter is not a Human!");
}
}

now we can do ...
class staff : IEnumerable
{
private Human[] employees = new Human[4];
public staff()
{
employees[0] = new Human("bob");
employees[1] = new Human("chris");
employees[2] = new Human("jennifer");
employees[3] = new Human("Brian");

}

public void donamesort()
{
//Array.Sort(employees);
Array.Sort(employees, new HumanNameComaparer());
}
public void donameSizesort()
{
//Array.Sort(employees);
Array.Sort(employees, new HumanNameSizeComaparer());
}
public IEnumerator GetEnumerator()
{
foreach (Human c in employees)
{
yield return c;
}
}
}

staff y = new staff();
foreach (Human h in y)
{
MessageBox.Show(h.Name);
}
y.donamesort();
foreach (Human h in y)
{
MessageBox.Show(h.Name);
}
y.donameSizesort();
foreach (Human h in y)
{
MessageBox.Show(h.Name);
}