Why the reference of an array is not changing?

class a
   {
       int[] cr=new int[10];      //think cr address is [3000]
       public void add(int[] br)   //getting 2000=>br
       {
           cr[0] = 111;           
           br=cr;                  //br=cr means br=3000,it doesn't mean ar=3000
       }                           //because it is value, not reference
   }
   class Program
   {

       static void Main(string[] args)
       {
              int[] ar = new int[10];   //think ar address is [2000] 
              ar[0] = 55;
           a obj = new a();
           obj.add(ar);      //passing 2000
           Console.WriteLine(ar[0]);

       }

try this:

class a
   {
       int[] cr=new int[10];
       public int[] add(/*int[] br*/)
       {
           cr[0] = 111;
           //br=cr;
           return cr;
       }
   }
   class Program
   {
 
       static void Main(string[] args)
       {
              int[] ar = new int[10];
              ar[0] = 55;
           a obj = new a();
           //obj.add(ar);
           arr = obj.add();
           Console.WriteLine(ar[0]);
 
       }

I did it quick and dirty, but I think it is because br is not coming out the function. if you want to pass an argument and change it, you need to use the ref or out keyword (see MSDN)

hope this helps.