Deleting selected rows from gridview using checkbox in vb.net

This program will show how to deleting selected rows from gridview using checkbox in vb.net

Imports System.Data

Partial Class _Default
    Inherits System.Web.UI.Page
    Public temptable As DataTable
    Public ds As DataSet
    Public editrow As DataRow
    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        temptable = Session("cart")
        editrow = temptable.NewRow
        editrow("Item_Name") = TextBox1.Text
        temptable.Rows.Add(editrow)
        Session("cart") = temptable
        GridView1.DataSource = temptable
        GridView1.DataBind()
    End Sub
'function for filling datatable
    Public Function makecart()
        Try
            temptable = New DataTable("cart")
            temptable.Columns.Add("id", GetType(Integer))
            temptable.Columns("id").AutoIncrement = True
            temptable.Columns("id").AutoIncrementSeed = 1
            temptable.Columns.Add("Item_Name", GetType(String))

            'put table in session
            Session("cart") = temptable

        Catch ex As Exception
            Response.Write(ex.Message)
        End Try
    End Function

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            makecart()

        End If
    End Sub

    'delete selected items
    Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
        temptable = Session("cart")
        For i As Integer = 0 To temptable.Rows.Count - 1
            If CType(GridView1.Rows(i).FindControl("CheckBox1"), CheckBox).Checked = True Then
                temptable.Rows(i).Delete()
            Else
                Dim a As Integer = 0
            End If
        Next
        Session("cart") = temptable
        GridView1.DataSource = temptable
        GridView1.DataBind()
    End Sub

    'selecting all at a time this handel check box in header row  
    Protected Sub CheckBox2_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles GridView1.RowCommand
        If CType(GridView1.HeaderRow.FindControl("CheckBox2"), CheckBox).Checked = True Then
            For i As Integer = 0 To GridView1.Rows.Count - 1
                CType(GridView1.Rows(i).FindControl("CheckBox1"), CheckBox).Checked = True
            Next
        Else
            For i As Integer = 0 To GridView1.Rows.Count - 1
                CType(GridView1.Rows(i).FindControl("CheckBox1"), CheckBox).Checked = False

            Next
        End If
   End Sub
End Class