Ten Basic Framework Functions Every VB Developer Should Know

Introduction

Hello, and welcome to today’s article. Today, I’d like to talk about ten of the basic .NET Framework functions (or methods) that every VB developer should know; but, before I can do that, I need to talk about Namespaces first.

.NET Framework

According to Microsoft, the .NET Framework is a computing platform that simplifies application development. This tells me nothing, honestly. Basically, the .NET Framework has come into existence to provide the following objectives:

• To provide a consistent, object-oriented programming environment, whether object code is stored and executed locally, executed locally but Internet-distributed, or executed remotely.
• To provide a code-execution environment that minimizes software deployment and versioning conflicts.
• To provide a code-execution environment that guarantees safe execution of code, including code created by an unknown or semi-trusted third party.
• To provide a code-execution environment that eliminates the performance problems of scripted or interpreted environments.
• To make the developer experience consistent across widely varying types of applications, such as Windows-based applications and Web-based applications.
• To build all communication on industry standards to ensure that code based on the .NET Framework can integrate with any other code.

Namespaces

A namespace contains types that you can use in your program. These types are: classes, structures, enumerations, delegates, and interfaces. Here is a list of most of the namespaces found in .NET Framework 4.5.

Now that you have an understanding of both the .NET Framework and what namespaces are, I can start showing you some of the most important (according to me) functions and namespaces that you should know about if you want to be a great VB programmer.

1. Asynchrony

Asynchrony is crucial to any app that depends on certain tasks that may cause bottlenecks or block the rest of your program, better yet, freezing. So, in fact, it makes the application respond quicker while running several tasks in the background.

Async and Await, as quoted from MSDN: “If you specify that a method is an async method by using an Async or async modifier, you enable the following two capabilities:

1. “The marked async method can use Await or await to designate suspension points. The await operator tells the compiler that the async method can’t continue past that point until the awaited asynchronous process is complete. In the meantime, control returns to the caller of the async method.
2. “The suspension of an async method at an await expression doesn’t constitute an exit from the method, and finally blocks don’t run.
   “The marked async method can itself be awaited by methods that call it.
   “An async method typically contains one or more occurrences of an await operator, but the absence of await expressions doesn’t cause a compiler error. If an async method doesn’t use an await operator to mark a suspension point, the method executes as a synchronous method does, despite the async modifier. The compiler issues a warning for such methods.”

For more information regarding Async and Await, have a read through an earlier article of mine: Async Programming.

2. String.Split

You can use Split to break a string apart and make many other little strings from it. How does this happen? Well, all you need to have is a delimiter. If you look at normal written language: We use a space as a separator between words so that we know which word starts where. In this case, a space is a delimiter. A delimiter can be any character, such as a comma, a period, a colon, or even a hyphen. It depends on your needs, ultimately. Here is a small example:

Dim SplitString As String = "Milk,Toast,Honey"
Dim SplitArr(2) As String

Dim i As Integer

'Split at Each Comma
SplitArr = SplitString.Split(","c)

For i = 0 To SplitArr.Length - 1

MessageBox.Show(SplitArr(i))

Next

If you look at the very first line of the preceding code segment, you will see that an object called SplitString is created. It contains the phrase: “Milk,Toast,Honey”. Now, notice the commas. Those commas are your delimiters. The next line creates an array with three elements (from 0 to 2). This will be used to store each phrase from the original string. An object named i is created; it will be used as a loop counter, a bit later. The next line is where the Splitting process actually happens. I employed the Split method to split at each comma character. Inside the loop, I simply displayed the contents of each array object. It should read:

Milk

Toast

Honey

The key to working with strings is to know what functions are available. There are actually many string functions available to Visual Basic developers. A detailed list of all of the string functions can be found at: http://msdn.microsoft.com/en-us/library/system.string_methods%28v=vs.110%29.aspx.

3. DateTime.AddDays

You can add any time or date onto an existing date or time. That sounds confusing, almost as the title of the Back to the Future movies! This simply means that if you have an existing date, you can add on to that date to get a future date or time. Now, why would we ever want to do this? It is simple: Any program should be able to compensate for future events. In a sense, your program should be able to see he future and make decisions based on that. Let me use a small example now: Let us say that you have a fruit market. Let us presume further that each of the fruits have expiry dates on them. You should be able to know when those fruit expire so that you can take them off of the shelves and not sell potentially almost rotten fruit to the public. Make sense now? Sure it does!

Our first Adding method is Add Days:

'Add Days

Dim dtToday As DateTime   'For Today's Date
Dim dtTomorrow As DateTime   'For Tomorrow's Date

dtToday = System.DateTime.Now   'Get Today's Date

dtTomorrow = dtToday.AddDays(1)  'Add A Day To A Date

'Show Nicely Formatted Date
MessageBox.Show("Today is : " & _
   dtToday.ToString("mmm-dd-yyyy"))

'Show Tomorrow's Date Formatted The Same Way
MessageBox.Show("Tomorrow is : " & _
   dtTomorrow.ToString("mmm-dd-yyyy"))

I created two DateTime objects. One is aptly named dtToday for today’s date and the next is named dtTomorrow, for tomorrow’s date. Although tomorrow’s date may be obvious to you, it is not for your program. I stored System.DateTime.Now inside dtToday. This gives me the precise date and time—more on this later—and I used the AddDays method to add one day to today’s date. This gives me tomorrow’s date. I show today’s date in a MessageBox as well as tomorrow’s date.

You will notice that I have made use of the ToString method to format the date like this: “mmm-dd-yyy”. This simply gives me: “25/01/2014”.

As with any class in the .NET Framework, the DateTime class has several properties and methods. Properties are simple settings that you can use to store and retrieve for an object, whereas methods are what that particular object can do. Here is a complete list of all the DateTime Properties and methods:

4. Database Command.ExecuteReader(CommandBehavior.Default)

Extracting data from databases is not complicated at all. Any developer needs to know how to do this because this is essentially what will make your app tick. Here is a small example of extracting information from a database table:

Private Sub btnSearch_Click(sender As Object, e As EventArgs) _
   Handles btnSearch.Click

   Try

      'Create A Command To Host Our Query
      Dim oSelCmd As OleDbCommand = New OleDbCommand

      'The Command Only Uses Text
      oSelCmd.CommandType = CommandType.Text

      'Set The Command's Connection
      oSelCmd.Connection = _
         Me.StudentInfoTableAdapter.Connection

      'Specify The Command
      oSelCmd.CommandText = strSearch & strSearchField _
         & strSearchValue

      'Open Connection
      Me.StudentInfoTableAdapter.Connection.Open()

      'Excute Command Via DataReader Object
      Dim oDr As OleDbDataReader = _
         oSelCmd.ExecuteReader(CommandBehavior.Default)

      'Construct A DataTable To Host Returned Values
      Dim dt As New DataTable

      'Declare Counter For Columns
      Dim i As Integer

      'How Many Fields Are There?
      Dim count As Integer = oDr.FieldCount - 1

      'Add Returned Columns To DataTable
      For i = 0 To count

      dt.Columns.Add(oDr.GetName(i), _
         oDr.GetFieldType(i))

   Next

      'Add Returned Rows To DataTable
      Do While oDr.Read()

      'Create A New Row
      Dim r As DataRow = dt.NewRow

      'Add All Records Returned
      For i = 0 To count

      r(i) = oDr.Item(i)

   Next

      'Add Rows
      dt.Rows.Add(r)

   Loop

      'Set DataGridView's DataSource To Show
      'Found Records
      Me.dgvStudents.DataSource = dt

   'General Exception, Can Narrow It Down Later
   Catch ex As Exception

      MessageBox.Show(ex.Message.ToString())   'Show Error

   Finally

      'Close Connection
      Me.StudentInfoTableAdapter.Connection.Close()

   End Try

End Sub

This is where all the database communication takes place. I did the following inside the Search button’s click event:

• Created a new command to execute on the database.
• Created a connection to the database, which is stored inside the Table Adapter’s connection.
• Specified my command which is the query I continuously built.
• Opened the connection.
• Executed the command, which is now my query.
• Created a Data Reader object to return the results found, if found at all.
• Created a new Data Table to store the results into. With this, I specified the columns I wanted, and looped through each found result.
• Set the DataGridView’s Data Source property to the new DataTable.
• Closed the connection.

Whatever gets returned is now placed inside the DataGridView, for example.

5. RegistryKey.OpenSubKey

Many people do not know what the Rregistry is, or how to use it. I used to be scared of the Registry. Why? Well, because the Registry is the place where all the settings are saved. It’s like an inventory where all the info about the programs, and the controls are stored. With the following code segment, I explore the HKEY_CLASSES_ROOTExcel.ApplicationCurVer key to determine what version of Microsoft Office is installed. This is where the information about Excel is stored. CurVer means Current Version. Now, we have to get the information out of there and use it to determine our actual comprehensible version. The information is stored like this:

Excel.Application.12

Very few people will know that this actually means Office 2007 because it is the 12th Office to be created. With some string manipulation, we extract the “12” and then do the test to see what version is present on the system. Not too difficult now, is it?

Private Sub Determine_OfficeVersion_2()
   '/HKEY_CLASSES_ROOT/Excel.Application/Curver
   Dim strEVersionSubKey As String = _
      "Excel.ApplicationCurVer"

   Dim strValue As String   'Value Present In Above Key
   Dim strVersion As String   'Determines Excel Version

   'Registry Key To Determine Excel Version
   Dim rkVersion As RegistryKey = Nothing

   'Open Registry Key
   rkVersion = Registry.ClassesRoot.OpenSubKey(name:=strEVersionSubKey, _
      writable:=False)

   If Not rkVersion Is Nothing Then   'If Key Exists

      strValue = rkVersion.GetValue(String.Empty)   'get Value

      'Store Value
      strValue = strValue.Substring(strValue.LastIndexOf(".") + 1)

      Select Case strValue   'Determine Version

          Case "7"

            strVersion = "95"

         Case "8"

            strVersion = "97"

         Case "9"

            strVersion = "2000"

         Case "10"

            strVersion = "2002"

         Case "11"

            strVersion = "2003"

         Case "12"

            strVersion = "2007"

         Case "14"

           strVersion = "2010"

      End Select

      'Display Result
      MessageBox.Show("Excel " & strVersion & _
         " Installed!")

   End If

End Sub

6. Clipboard.SetText(SelectedText)

Through the years, access to the Clipboard object has become easier and easier. Here is a small example on using the Clipboard to copy, cut, and paste information to and from textboxes:

Private Sub btnClipCopy_Click(ByVal sender As System.Object, _
   ByVal e As System.EventArgs) Handles btnClipCopy.Click
   If txtSource.Text <> "" Then
      If txtSource.SelectionLength > 0 Then
         strSelectedText = txtSource.SelectedText
         'put selection on Clipboard
         Clipboard.SetText(strSelectedText)
      Else
         txtSource.SelectAll()
         'put all text on Clipboard
         Clipboard.SetText(txtSource.Text)
      End If
   End If
End Sub

Private Sub btnClipCut_Click(ByVal sender As System.Object, _
   ByVal e As System.EventArgs) Handles btnClipCut.Click

   If txtSource.Text <> "" Then
      If txtSource.SelectionLength > 0 Then
         strSelectedText = txtSource.SelectedText
         Clipboard.SetText(strSelectedText)
         'clear text, for cutting; otherwise, it's same as copy
         txtSource.SelectedText = ""
      Else
         txtSource.SelectAll()
         Clipboard.SetText(txtSource.Text)
         txtSource.Text = ""
      End If
   End If
End Sub

Private Sub btnClipPaste_Click(ByVal sender As System.Object, _
   ByVal e As System.EventArgs) Handles btnClipPaste.Click
   Dim ClipText As String   'store text from clipboard
   Dim OldText As String   'previous text in textbox
   OldText = txtDest.Text   'store previous text
   ClipText = Clipboard.GetText   'get the clipboard contents
   'to paste at back of text.
   'Otherwise, just say textbox2.text = cliptext
   txtDest.Text = OldText & ClipText
End Sub

7. CultureInfo.GetCultures(CultureTypes.AllCultures)

Globalization is basically the process of making your application culture-friendly. You have to realize that the users of your application may speak a different language than you, and therefore their language adheres to different rules, apart from being a different language. For example, some languages are displayed left to right, while others should be displayed right to left. Now, you have to not only think about the different language, but different currencies, date and time settings, as well as different colours being used with different cultures.

With Globalization, you can make your application useable with any culture irrespective of their language. Here are some more articles on Globalization:

• http://msdn.microsoft.com/en-us/library/vstudio/system.globalization.cultureinfo
• http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo%28v=vs.80%29.aspx
• http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo%28vs.71%29.aspx
• http://www1.cs.columbia.edu/~lok/csharp/refdocs/System.Globalization/types/CultureInfo.html

Private Sub Form1_Load(sender As Object, e As EventArgs) _
   Handles MyBase.Load

   ' Get & Enumerate All Cultures.
   ciAllCultures = _
      CultureInfo.GetCultures(CultureTypes.AllCultures)

   Dim ciCurrentCulture As CultureInfo

   For Each ciCurrentCulture In ciAllCultures

      ' Display Name Of Each Culture And English Name
      ComboBox1.Items.Add(ciCurrentCulture.Name & " [ " _
         & ciCurrentCulture.EnglishName & " ]")

   Next

End Sub

The first line of code obtains all the cultures and stores them inside the ciAllCultures array. Then, I looped through each of the cultures and loaded them inside the Combobox. Inside the Combobox, I display both the Culture’s native name as well as its English name. The user is now able to select any culture from this list.

8. Generic Lists

According to MSDN, “a Generic List represents a strongly typed list of objects that can be accessed by an index. Provides methods to search, sort, and manipulate lists.” This is very vague and does not tell anyone about a Generic List’s use and advantages. Let me try to explain it better: A Generic List is simply a list that you can make yourself. This list can be anything! An example of a generic List will be a student list. Do not think of the Student list as containing only the student’s names; it can contain all methods and properties associated with a student object.

This means that you can create a Student class, supply some properties to it, and then make a list of Students that will contain all the Student object’s properties and methods.

An example follows:

Public Class Students

   Private strStudentSurname As String
   Private strStudentName As String

   'Student Name Property
   Public Property StudentName() As String

      Get

         Return strStudentName

      End Get

      Set

         strStudentName = Value

      End Set

   End Property

   'StudentSurname Property
   Public Property StudentSurname() As String

      Get

         Return strStudentSurname

      End Get

      Set

         strStudentSurname = Value

      End Set

   End Property

   'ToString Method
   Public Overrides Function ToString() As String

      Return "Name: " & StudentName & _
         " Surname: " & StudentSurname

   End Function

   'Equals Method
   Public Overrides Function Equals(objTemp As Object) _
      As Boolean

      If objTemp Is Nothing Then Return False

      Dim objAsStudent As Students = _
         TryCast(objTemp, Students)

      If objAsStudent Is Nothing Then

         Return False

      Else

         eturn Equals(objAsStudent)

      End If

   End Function
End Class

I added Properties for the Student Class. This gives us a way to get and set the Student name and Surname. Next, I added some methods. These methods enable us to check an object’s existence inside the list, as well as to return the appropriate object when referenced.

Now, let’s use this list of Students inside our form!

Import the Generic Lists namespace:

Imports System.Collections.Generic

Create the physical list:

'Create List Of Students
Private lstStudents As List(Of Students) = _
   New List(Of Students)

This creates a list of students, with all its associated properties and methods.

Adding items to a Generic List

Add the next code segment to a button:

Private Sub btnAdd_Click( sender As Object, e As EventArgs) _
   Handles btnAdd.Click
   'Add Supplied Student Details To List
   lstStudents.Add(New Students() With { _
      .StudentName = txtStudentName.Text, _
      .StudentSurname = txtStudentSurname.Text _
   })
   txtStudentName.Text = "" txtStudentSurname.Text = ""
End Sub

This adds whatever was entered in the txtStudentName and txtStudentSurname textboxes and adds it to the generic List.

9. System.IO

System.IO allows us access to a PC’s filesystem. Here is a small example:

Private Sub AddAllFolders(ByVal TNode As TreeNode, _
   ByVal FolderPath As String)

   Try

      'Load All Sub Folders
      For Each FolderNode As String In Directory.GetDirectories(FolderPath)

      'Add Each Sub Folder Name
      Dim SubFolderNode As TreeNode = TNode.Nodes.Add(FolderNode.Substring _
         (FolderNode.LastIndexOf(""c) + 1))

      SubFolderNode.Tag = FolderNode   'Set Tag For Each Sub Folder

      SubFolderNode.Nodes.Add("Loading...")

   Next

   Catch ex As Exception

      MessageBox.Show(ex.Message)    '  Something Went Wrong

   End Try

This example uses System.IO to get all the directories (folders) inside another folder and adds them to a Treeview.

10. Color.FromArgb

I just had to add something form the System.Drawing namespace; the temptation was a bit too much to resist. Obviously, this is not one of the most commonly used functions from the System.Drawing namespace, but it has its uses. The Color.FromArgb method returns an RGB color value plus a transparancy value. RGB means Red Green Blue.

Conclusion

I hope you have enjoyed today’s article. Until next time, cheers!