' Visual Basic 2008 9.0 .NET Examples - Introduction to Procedures - Procedures and Functions : 
Module Example4
    Sub Main()
        Dim menu As Char
        Dim value As Decimal
        '
        Console.Write("1 centimetres -> inches / 2 - inches -> centimetres : ")
        menu = Console.ReadLine()
        Do Until menu = "1"c OrElse menu = "2"c
            ShowError("An illegal menu option is chosen.")
            Console.Write("1 centimetres -> inches / 2 - inches -> centimetres : ")
            menu = Console.ReadLine()
        Loop
        '
        Console.Write("Value : ")
        value = Console.ReadLine()
        Do Until value > 0
            ShowError("The value should be above zero.")
            Console.Write("Value : ")
            value = Console.ReadLine()
        Loop
        '
        If menu = "1"c Then
            Console.WriteLine(value & " centimetres is " & value * 0.3937 & " inches")
        Else
            Console.WriteLine(value & " inches is " & value * 2.54 & " centimetres")
        End If
        '
        Console.ReadLine()
    End Sub
    Sub ShowError(ByVal message As String)
        Console.WriteLine(message & "  Please try again.")
    End Sub
End Module
' Visit www.studyvb.com for more examples.  Copyright 2003-2008 De Wolf.