Singleton class in c#

->How to restrict object creation to only one objectaspx means u only assign one class one object(ussing singleton class)
->Singleton class:A singleton class is a class on which we can create only oneobject at any given point of time
 ->Also we r get only one O/P  bec in singleton class we can get another O/p

Sample code:

public partial class How_to_restrict_object_creation_to_only_one_objectaspx : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
         B b1 = B.m(20);
        B a1 = B.m(30);
        Response.Write(a1.x);
        Response.Write(b1.x);
     }
}
public class B
{
    public int x;
    private static B a;
    public static int count = 0;
    private B(int x)
    {
        this.x = x;
    }
    public static B m(int y)
    {
        if (count == 0)
        {
            a = new B(y);
        }
        return a;
    }
}