Class TCommandLineParser lets developer configure a syntax of command line. VB.NET TCommandLineParser class is almost full clone of the same C++ class (see PARSING COMMAND LINE IN C++). Command line syntax is defined using parameters - building blocks of command line.

'
'  Main.vb - TCommandLineParser class functionality test
'
' argument order doesn't matter
' parameter names are case insensitive
' command line argument must follow this rule: /xxxxxx=yyyyyy or /xxxxxx
' where "xxxxxx" is argument (parameter) name and yyyyyy it's value. Argument w/o value 
' we call switch. Please note that there must be no spaces near '=' !!! and parameter name 
' should start with symbol from [a-z_] range.
' these names are valid: "abc", "_k", "_a9" "aa222"
' these names are invalid: "1a", "_12", "5_a", "__"
' Valid command lines (for example below)
'/Void2 /Name1="NAME1 NAME2" /Int1=1 /Int2=2 /arr=1 /arr=2 /VOID1 /positive=1 /bounded1=2 /Bounded1=3
'/Name1="Parameter that contains spaces must be quoted!" /Optional1=blablabla /Int1=666 /arr=1 /positive=1 /bounded1=2 /Bounded1=3 /arr=33
' invalid example (mandatory parameter "Name1" is missing!
'/Int1=666 /arr=1 /positive=1 /bounded1=1
'/name1=abcde /Int1=666 /arr=1 /positive=0 /bounded1=1


Module Main

    ' place to print parameters usage
    Public Sub Usage()
        Console.WriteLine("Usage:")
        ' print here parameters descriptions
        ' ..............
    End Sub


    Sub Main(ByVal args() As String)

        Console.WriteLine("TCommandLineParser illustration")
        Console.WriteLine()
        Try
            ' create command line object
            Dim commandline As New TCommandLineParser
            ' and declare it's syntax
            With commandline
                ' mandatory string-valued parameter "Name1"
                .AddString("Name1", True)
                ' optional string-valued parameter "Optional1"
                .AddString("Optional1")
                ' mandatory integer-valued parameter "Int1"
                .AddInt("Int1", True)
                ' optional integer-valued parameter "Int2"
                .AddInt("Int2")
                ' optional switch "Void1" (switches are always optional!)
                .AddVoid("Void1")
                ' optional switch "Void2"
                .AddVoid("Void2")
                ' optional integer-valued repeatable parameter "Arr"
                .AddIntRep("Arr")
                'optional integer parameter "default"
                .AddInt("default")
                'optional positive integer-valued parameter "positive" (accepts only positive integer values: 1,2,3,...)
                .AddPosInt("positive")
                'optional bounded repeatable integer-valued parameter "bounded2" (accepts onluy values: 1,2,3,4,5)
                .AddBoundedIntRep("bounded1", 1, 5)
                'optional switches
                .AddVoid("help")
                .AddVoid("h")
            End With

            ' feed commandline object with given arguments
            commandline.AddItems(args)

            ' perform validation of command line arguments
            ' really method Validate() will return false only when at least
            ' one mandatory parameter was not initialized (doesn't present in command line)
            If Not commandline.Validate() Then
                Console.WriteLine("Missing some mandatory parameter in command line!")
                Console.ReadLine()
                Return
            End If

            ' if /help or /h was found in command line -> display help and terminate
            If commandline.FindValue("help") Or commandline.FindValue("h") Then
                Usage()
                Return
            End If

            ' the simple way to make parameter default
            ' first, look if parameter "default" really presents in command line
            If Not commandline.FindValue("DEFAULT") Then
                ' if not manually add it supplied with some (default) value
                commandline.AddItem("/default=1")
            End If

            With commandline
                Console.WriteLine("/Name1={0}", .GetString("Name1"))
                ' for optional valued parameters we need first to find them in command line
                If .FindValue("Optional1") Then
                    ' and only after that get its value
                    Console.WriteLine("/Optional1={0}", .GetString("Optional1"))
                End If
                Console.WriteLine("/Int1={0}", .GetInt("Int1"))
                If .FindValue("Int2") Then
                    Console.WriteLine("/Int2={0}", .GetInt("Int2"))
                End If
                If .FindValue("Void1") Then
                    Console.WriteLine("/Void1")
                End If
                If .FindValue("Void2") Then
                    Console.WriteLine("/Void2")
                End If
                If .FindValue("arr") Then
                    ' since "arr" is repeatable parameter - get number of occurences
                    Dim N As Integer = .Count("ARR")
                    Console.WriteLine("Count(""Arr"")={0}", N)
                    For j As Integer = 0 To N - 1
                        Console.WriteLine("/arr={0}", .GetInt("arr", j))
                    Next
                End If

                If .FindValue("positive") Then
                    Console.WriteLine("/positive={0}", .GetInt("positive"))
                End If


                If .FindValue("bounded1") Then
                    Dim N As Integer = .Count("bounded1")
                    Console.WriteLine("Count(""bounded1"")={0}", N)
                    For j As Integer = 0 To N - 1
                        Console.WriteLine("/bounded1={0}", .GetInt("bounded1", j))
                    Next
                    ' now clear values (it seems like this parameter wasn't in command line)
                    .ClearValue("BOUNDED1")
                    ' was it really deleted?
                    If .FindValue("bounded1") Then
                        Console.WriteLine("No, ""bounded1"" is still here")
                    Else
                        Console.WriteLine("Yes, ""bounded1"" has been removed from command line object")
                    End If
                End If

            End With

        Catch ex As Exception
            Console.WriteLine("Exception caught: {0}", ex.Message)
        End Try
        Console.ReadLine()
    End Sub

End Module