public static void ArrayDemo(){
     string[]  a1;                     // a1 is uninitialized
     string[]  a2 = new string[3];     // an array with three null values

     string[]  a3 = {"a", "bb", "ccc"};     // an array with 3 strings
     string[]  a4 = new string[]{"a", "bb", "ccc"};   // equivalent
     string[]  a5 = new string[3]{"a", "bb", "ccc"};  // equivalent

//   string[]  a6 = new string[2]{"c", "b", "a"};  
//   Compile time error 
//   'Invalid rank specifier'. Not space enough in array. Omit [2]

     // a1 is assigned to a new string array.
     a1 = new string[]{"a", "bb", "ccc"};

     int[,]    b1 = new int[2,4];   
                                  // 2 rows, 4 columns
                                  // all initialized to default(int)

     int[,]    b2 = {{1,2,3,4}, {5,6,7,8}};   
     int[,]    b3 = new int[2,4]{{1,2,3,4}, {5,6,7,8}};  // equivalent

//   int[,]    b4 = new int[3,4]{{1,2,3,4}, {5,6,7,8}};  
//   Compile time error
//   'Invalid rank specifier'. Add a third row.

     // b1 is assigned to a new int arrays. 2 rows, 4 columns
     b1 = new int[,]{{1,2}, {3,4}, {5,6}, {7,8} };

     double[][] c1 = { new double[]{1.1, 2.2}, 
                       new double[]{3.3, 4.4, 5.5, 6.6} };

     Console.WriteLine("Array lengths. a1:{0} b3:{1} c1:{2}", 
                        a1.Length, b3.Length, c1.Length);
     // 3, 8, 2

     Array.Clear(a2,0,3);  // Set a[0], a[1], a[2] to default values 

     Console.WriteLine("Length of a3: {0}", a3.Length);  // 3
     Array.Resize<string>(ref a3,10);
     Console.WriteLine("Lenght of a3: {0}", a3.Length);  // 10

     Console.WriteLine("Ranks of b1 and c1: {0}, {1}", b1.Rank, c1.Rank);
     // 2, 1

     Console.WriteLine("Sorting:");
     Array.Sort(a5);
     foreach(string str in a5) Console.WriteLine(str);

  }