Spiral traversal of matrix in vb.net

Vb program for Spiral traversal of matrix. Here problem description and explanation.

' Include namespace system
Imports System 
'  Vb.net program for 
'  Spiral form of matrix
public Class SpiralView 
    Public Sub spiral(ByVal data As Integer(,), 
      ByVal startRow As Integer, 
        ByVal startCol As Integer, 
          ByVal endRow As Integer, 
            ByVal endCol As Integer, 
              ByVal element As Integer)
        '  Left to right
        Dim i As Integer = startCol
        While i <= endCol AndAlso
		 element > 0

            element -= 1
            Console.Write("  " + data(startRow,i).ToString())
        i += 1
        End While
        '  Top to down
        i = startRow + 1
        While i <= endRow AndAlso
		 element > 0

            element -= 1
            Console.Write("  " + data(i,endCol).ToString())
        i += 1
        End While
        '  Bottom right to bottom-left
        i  = endCol - 1
        While i >= startCol AndAlso
		 element > 0

            element -= 1
            Console.Write("  " + data(endRow,i).ToString())
        i -= 1
        End While
        '  Bottom left to top
        i = endRow - 1
        While i > startRow AndAlso
		 element > 0

            element -= 1
            Console.Write("  " + data(i,startRow).ToString())
        i -= 1
        End While
        if (startRow + 1 <= endRow - 1 AndAlso
		 element > 0) Then 
            '  Recursive call
            Me.spiral(data, startRow + 1, 
                      startCol + 1, 
                      endRow - 1, 
                      endCol - 1, 
                      element)
        End If

    
    End Sub
    
    Public Shared Sub Main(ByVal args As String())
        Dim task As SpiralView = New SpiralView()
        '  Given matrix
        Dim matrix As Integer(,) = 
        {
        {1, 2, 3, 4, 5, 6}, 
        {22, 23, 24, 25, 26, 7}, 
        {21, 36, 37, 38, 27, 8}, 
        {20, 35, 42, 39, 28, 9}, 
        {19, 34, 41, 40, 29, 10}, 
        {18, 33, 32, 31, 30, 11}, 
        {17, 16, 15, 14, 13, 12}}
        Dim row As Integer = matrix.GetLength(0)
        Dim col As Integer = matrix.GetLength(1)
        '  Get the number of element
        Dim element As Integer = row * col
        task.spiral(matrix, 0, 0, row - 1, col - 1, element)
    
    End Sub

End Class

Output

  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42