Visual Basic 2008 9.0 .NET Examples and Ebook

When no upperbound is used in the declaration of an array variable, the array can be initialized. This can be done by adding an initialization clause to the declaration, containing initial element values, separated by commas, and surrounded by braces ( {...} ).

The arrayinitializer is a expression that will create the array instance ( with the defined values ), and will evaluate to the reference of that array instance. That reference can then be assigned to the array variable.

Module Example
    Sub Main()
        Dim indexFirstDimension As Integer
        Dim indexSecondDimension As Integer
        Dim indexThirdDimension As Integer
        '
        Dim row() As Integer = {1, 2, 3, 4, 5, 6}
        For indexFirstDimension = 0 To 5
            Console.Write(row(indexFirstDimension) & " ")
        Next
        Console.WriteLine()
        '
        Dim matrix(,) As Integer = {{1, 2, 3, 4, 5, 6}, _
                                    {7, 8, 9, 10, 11, 12}}                 ' (1)
        For indexFirstDimension = 0 To 1
            For indexSecondDimension = 0 To 5
                Console.Write(matrix(indexFirstDimension, _
                                     indexSecondDimension) & " ")
            Next
        Next
        Console.WriteLine()
        '
        Dim cube(,,) As Integer = {{{1, 2, 3}, _
                                    {4, 5, 6}}, _
                                   {{7, 8, 9}, _
                                    {10, 11, 12}}, _
                                   {{13, 14, 15}, _
                                    {16, 17, 18}}, _
                                   {{19, 20, 21}, _
                                    {22, 23, 24}}}                         ' (2)
        For indexFirstDimension = 0 To 3
            For indexSecondDimension = 0 To 1
                For indexThirdDimension = 0 To 2
                    Console.Write(cube(indexFirstDimension, _
                                       indexSecondDimension, _
                                       indexThirdDimension) & " ")
                Next
            Next
        Next
        '
        Console.ReadLine()
    End Sub
End Module

Output :

 1 2 3 4 5 6
 1 2 3 4 5 6 7 8 9 10 11 12
 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

row :

 1st index : 0 1 2 3 4 5
     value : 1 2 3 4 5 6

matrix :

 1st index : 0 0 0 0 0 0 1 1 1 1  1  1
 2nd index : 0 1 2 3 4 5 0 1 2 3  4  5
     value : 1 2 3 4 5 6 7 8 9 10 11 12

matrix :

 1st index : 0 0 0 0 0 0 1 1 1 1  1  1  2  2  2  2  2  2  3  3  3  3  3  3
 2nd index : 0 0 0 1 1 1 0 0 0 1  1  1  0  0  0  1  1  1  0  0  0  1  1  1
 3rd index : 0 1 2 0 1 2 0 1 2 0  1  2  0  1  2  0  1  2  0  1  2  0  1  2
     value : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Task :

Create a program that can convert integral values ( between 0 and 4000 ) to a Roman numeral.

I = 1, IV = 4, V = 5, IX = 9, X = 10, XL = 40, L = 50, XC = 90, C = 100, CD = 400, D = 500, CM = 900, M = 1000

Use arrays to store these symbols and conversion values.

Output :

 Value ?
 -1
 Value ?
 4000
 Value ?
 1
 I
 Value ?
 3999
 MMMCMXCIX
 Value ?
 2789
 MMDCCLXXXIX
 Value ?

Solution :

Module ExerciseSolution
    Sub Main()
        Dim symbols() As String = _
         {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"}
        Dim units() As Integer = _
                          {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}
        '
        Dim value, index As Integer
        Do
            Do
                Console.WriteLine("Value ?")
                value = Console.ReadLine()
            Loop Until value < 4000 AndAlso value >= 0
            For index = 0 To 12
                Do While value >= units(index)
                    Console.Write(symbols(index))
                    value -= units(index)
                Loop
            Next
            Console.WriteLine()
        Loop
    End Sub
End Module