Choose Visual Basic Example

VB.NET > Functions > Choose

Returns a member of the list passed in Choice().
It is based on the value of Index. The first member of the list is selected when Index is 1.

Example

Dim choice = Choose(2, "val1", "val2", "val2") // "val2"

Day VB.Net Example

VB.NET > Functions > Day

Day returns the day of the month as an integer between 1 and 31.

Example


Dim today As Integer = Microsoft.VisualBasic.DateAndTime.Day(Now)

How to get if is Runtime or Design Mode VB.net

VB.NET > Control > DesignMode

DesignMode returns true is a control is being used in the context of a designer. 

Example:

If Me.DesignMode Then
      Return
End If

DateValue Visual Basic Example

VB.NET > Functions > DateValue 

Returns a date value containing the date information represented by a string.

Example

Dim dt As Date

dt = DateValue("March 21, 2014")

MessageBox.Show(dt)

DateDiff Visual Basic Example

VB.NET > Functions > DateDiff

Returns a value specifying the number of time intervals 
between two dates.

Example:

Dim dt1 As Date = #3/1/2014#

Dim dt2 As Date = #4/1/2014#

MessageBox.Show("Day diff: " & DateDiff(DateInterval.Day, dt1, dt2) & " Week diff: " & DateDiff(DateInterval.Weekday, dt1, dt2))

AppActivate Visual Basic

VB.NET > Functions > AppActivate

Activates an application that is already running.

Example:
Start and activate notepad

AppActivate(Shell("C:\Windows\System32\notepad.exe", AppWinStyle.NormalFocus))

CurDir Visual Basic

VB.NET > Functions > CurDir 

Returns the current path.

Example:

MessageBox.Show(CurDir())

Call Statement VB.NET Example

VB.NET > Statements > Call

Call transfers control to a function or dynamic-link library.

Call keyword is used when the called expression doesn't start with an identifier.

Example:

Class mClass

    Public Sub Method()

        MessageBox.Show("Call statement")

    End Sub

End Class

Public Class Form1

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

        Call New mClass().Method()

    End Sub

End Class

Rss Feed Reader Vb.net Example

VB.NET > XML > Rss Feed Reader






Example

 Dim url As String = "http://rss.cnn.com/rss/cnn_latest.rss"

        Dim rssFeed As HttpWebRequest = DirectCast(WebRequest.Create(url), HttpWebRequest)

        Dim response = rssFeed.GetResponse()

        Dim rssStream = response.GetResponseStream()

        Dim rssDoc As New XmlDocument()

        rssDoc.Load(rssStream)

        Dim rssItems As XmlNodeList = rssDoc.SelectNodes("rss/channel/item")

        Dim i As Integer = 0

        Dim dt As DataTable = New DataTable("table")

        dt.Columns.Add("title", Type.GetType("System.String"))

        dt.Columns.Add("link", Type.GetType("System.String"))

        While i < rssItems.Count

            Dim node As XmlNode = rssItems.Item(i).SelectSingleNode("title")

            Dim title As String

            Dim link As String

            If node IsNot Nothing Then

                title = node.InnerText

            Else

                title = ""

            End If

            node = rssItems.Item(i).SelectSingleNode("link")

            If node IsNot Nothing Then

                link = node.InnerText

            Else

                link = ""

            End If

            Dim dr As DataRow = dt.NewRow()

            dr("title") = title

            dr("link") = link

            dt.Rows.Add(dr)

            i += 1

        End While

        DataGridView1.DataSource = dt

#Region Directive Visual Basic Example

Visual Basic > Directives > #Region

Collapses and hides sections of code.

Example:

Public Class Form1

#Region "Person"

    Public Class Person

    End Class

#End Region

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

    End Sub

End Class

LINQ DataTable compare date VB.NET

VB.NET > Data > DataTable > Filter with LINQ

LINQ DataTable compare date VB.NET example

   Dim dt As DataTable = New DataTable("table")

        dt.Columns.Add("id", Type.GetType("System.Int32"))
        dt.Columns.Add("name", Type.GetType("System.String"))
        dt.Columns.Add("date_of_birth", Type.GetType("System.DateTime"))
 

        Dim dr As DataRow = dt.NewRow()

        dr("id") = 1
        dr("name") = "john"
        dr("date_of_birth") = #1/1/2000#
        dt.Rows.Add(dr)

        dr = dt.NewRow()

        dr("id") = 2
        dr("name") = "dan"
        dr("date_of_birth") = #9/11/1973#
        dt.Rows.Add(dr)

        Dim filteredTable As DataTable = (From n In dt.AsEnumerable()

                            Where n.Field(Of Date)("date_of_birth") = #9/11/1973#
                    Select n).CopyToDataTable()

DateAdd VB.NET Example

VB.NET > Functions > DateAdd

DateAdd: add or subtract a specified time interval from a date.

Example:

Label1.Text = Date.Now
Label2.Text = DateAdd(DateInterval.Day, 1, Date.Now)
Label3.Text = DateAdd(DateInterval.Month, 1, Date.Now)
Label4.Text = DateAdd(DateInterval.Year, 1, Date.Now)

Delete row from DataTable using LINQ VB.NET example

VB.NET > DataTable > Delete row with LINQ

Here is an example of deleting row from DataTable (dt) supposing you want to delete the row with id 1.

Dim row As DataRow = dt.AsEnumerable().SingleOrDefault(Function(r) r(0) = 1)

If Not row Is Nothing Then

    row.Delete()
End If
  

Add AutoIncrement Row Values to DataTable Having AutoIncrement and PrimaryKey DataColumn

VB.NET > DataGridView > Add AutoIncrement Row Values

Example how to add AutoIncrement and PrimaryKey DataColumn values to DataTable

VB.NET

  Dim dt As DataTable = New DataTable

  dt.Columns.Add("ID", GetType(Integer))

  dt.PrimaryKey = New DataColumn() {dt.Columns("ID")}
  dt.Columns("ID").AutoIncrement = True
  dt.Columns("ID").AutoIncrementSeed = 1
  dt.Columns("ID").ReadOnly = True

  dt.Columns.Add("Name", GetType(String))

  Dim dr = dt.NewRow()
  dr("Name") = "John"
  dt.Rows.Add(dr)

  dr = dt.NewRow()

  dr("Name") = "Dan"
   dt.Rows.Add(dr)

  DataGridView1.DataSource = dt

C#

DataTable dt = new DataTable();

dt.Columns.Add("ID", typeof(int));
dt.PrimaryKey = new DataColumn[] { dt.Columns["ID"] };
dt.Columns["ID"].AutoIncrement = true;
dt.Columns["ID"].AutoIncrementSeed = 1;
dt.Columns["ID"].ReadOnly = true;

dt.Columns.Add("Name", typeof(string));

dynamic dr = dt.NewRow();
dr("Name") = "John";
dt.Rows.Add(dr);

dr = dt.NewRow();
dr("Name") = "Dan";
dt.Rows.Add(dr);

DataGridView1.DataSource = dt;