Introduction to the Common Language Runtime in VB.NET

Category:

C#, VB.NET, ASP.NET

Type:

Modules

Difficulty:

Beginning

Author: Franz Hemmer

Version Compatibility: Visual Basic.NET

More information:

This little module will show how to use a few of the many classes in the Common Language Runtime of .NET. Use it to explore the many features of the CLR, and add to it yourself to gain a better understanding of the many features.

Originally developed for Beta versions; verified to work in VB.NET Version 1.0, 03/31/02.

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
Imports Microsoft.Win32 Imports System Imports System.Configuration Imports System.Data Imports System.Diagnostics

Code:

Module modMain
    '*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*
    '*          Sub Main()                                   *
    '*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*
    Public Sub Main()
        Dim lAppDomain As System.AppDomain
        Dim lBuffer As New System.Collections.Specialized.StringCollection()
        Try
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' Small StringCollection class example:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            lBuffer.Add("1")
            lBuffer.Add("2")
            Debug.WriteLine(lBuffer)
            Debug.WriteLine(lBuffer.Count)

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' Getting information from the AppDomain:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Debug.WriteLine(lAppDomain.CurrentDomain.BaseDirectory)
            Debug.WriteLine(lAppDomain.CurrentDomain.FriendlyName)

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' Note that you can reference System.AppDomain directly!
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Debug.WriteLine(System.AppDomain.CurrentDomain.ToString)

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' System.Convert example:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Dim lConvert As System.Convert
            Debug.WriteLine(lConvert.ToInt32("100"))

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' EventLog example:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Dim lEventLog As System.Diagnostics.EventLog()
            Dim x As Integer
            Dim y As Integer

lEventLog = System.Diagnostics.EventLog.GetEventLogs()
            For x = 1 To lEventLog.Length
                Debug.WriteLine("Log Type: " & lEventLog(x - _
                  1).Log.ToString & lEventLog(x - 1).Entries.Count _
                    & " entries.")
                '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                ' If you want the details of the eventlog entries,
                ' uncomment the
                ' lines below.
                '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                'For y = 1 To lEventLog(x - 1).Entries.Count
                '   Debug.WriteLine(lEventLog(x - 1).Entries(y - _
                '      1).TimeGenerated.ToString & " - " & _
                '      lEventLog(x - 1).Entries(y - 1).Message)
                'Next y
            Next x
            ' Testing how to write the the event log:
            lEventLog(0).WriteEntry("Test", "Hello There!!")

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' Date examples:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Dim lDate As System.DateTime
            If lDate.IsLeapYear(System.Date.Today.Year) = True Then
                Debug.WriteLine("This year is a leap year!")
            Else
                Debug.WriteLine("This year is not a leap year!")
            End If

Dim lBirthDateStr As String
            Dim lBirthDate As System.DateTime

lBirthDateStr = InputBox _
             ("Enter your birthdate (dd-mm-yyyy):", _
              "Calculating your age")
            lBirthDate = System.DateTime.Parse(lBirthDateStr)
            Debug.WriteLine("You are " & _
               CInt(System.DateTime.Now.Subtract _
              (lBirthDate).TotalDays) & " days old.")

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' System.Diagnostics.Process example:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Dim lProcessArray As System.Diagnostics.Process()
            lProcessArray = System.Diagnostics.Process.GetProcesses
            Debug.WriteLine("There are: " & _
               lProcessArray.Length.ToString & _
               " processess currently running.")
            For x = 1 To lProcessArray.Length
                Debug.WriteLine(lProcessArray(x - 1).ProcessName)
            Next x

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            ' System.Environment examples:
            '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Dim lEnv As System.Environment
            Dim lDrives As String()

Debug.WriteLine(lEnv.CurrentDirectory.ToString)
            lDrives = lEnv.GetLogicalDrives()
            For x = 1 To lDrives.Length
                Debug.WriteLine(lDrives(x - 1))
            Next
            Debug.WriteLine(lEnv.OSVersion.ToString)

Catch ex As Exception
            MsgBox(ex.Message)

Finally
            MsgBox("Done", _
             Microsoft.VisualBasic.MsgBoxStyle.Information, "Done")
        End Try
    End Sub

End Module