Visual Basic .Net

VB .net © COPYRIGHT BY BADBOY INC PRESENTED BY:SIR “JPACS”

Visual Basic .net

Mr. Jose Marie M. Pacia


Visual Studio .net

• Microsoft’s Integrated Development Environment (IDE) for creating running and debugging programs (called applications) written in variety of programming languages


Why move from VB6 to .Net?

• World of applications is changing• Has a number of unique features


Overview of Visual Studio .net

• Start Page – contains list of helpful links• There are two buttons on the page:

– Open Project– New Project

• To create a new project click new project


Create New Project

Open Existing Project


Up close…

• Variety of languages– Visual Basic Projects– Visual C# Projects– Visual C++ Projects– Setup and Deployment Projects– Visual Studio Solutions


Visual Basic Projects

• Windows application – a program that executes inside a windows OS. – Include customized software that programmers create,

example Microsoft Word, IE6 ect.


Project Name

Create Applications


Project Name

Path


Console Programming

• Console application – applications contain only text output• Visual Basic console applications consist of pieces called module


Changing the default Module

• Click on Project > Console Properties• On the startup object change the startup object to your startup

module


To run a program

• On the menu bar press Debug• Click start without debugging (F5 for shortcut key)


Console Programming

• Printing a text– Consolse.Write(“String”)– Console.WriteLine(“The text goes here!”)

• Writeline position the text in the beginning of the next line


Example 1

• VB.net\LaboratoryExercise\PrintingText


Variables

• Stores data or information during program execution• How to declare

– Dim variable_Name as Data_Type– To insert a value:

• Dim variable_Name as Data_Type = Value


Note

• Before VB can use an object variable, it must determine its type and perform the necessary conversions, if any.


Data Types

• Types of Variables– Numeric – Store Numbers


Arithmetic Operators

• Addition - +• Subtraction - -• Multiplication - *• Division - /• Division (Integer) \• Modulus - Mod• Exponentiation - ^


Example 2

• \VB.net\LaboratoryExercise\ConsoleCalculator\ConsoleCalC


Character Variables

• You can initialize a character variable by assigning either a character or a string to it. In the latter case, only the first character of the string is assigned to the variable.– Dim string_varialble as string– Dim string_varialble as string = “Value”


Concatenation

• Joining of two or more strings• Example• Dim string1 as string = “a”• Dim string 2 as string = “b”

– String1 & string2• ab


Example 3

• VB.net\LaboratoryExercise\StringManipulation\StringManipulation


Equality Operators

• = - Equals• <> - Not Equal• > - Greater Than• < - Less Than• >= - Greater Than Equal• <= - Less than equal


If then

If studentGrade>=60 then Console.WriteLine(“Passed”)

End If


Decision Making

• If/then– Allows a program to make a decision based on the truth or

falsity of some expression – It is a condition


Module Condition

Sub Main() Dim lagyu As String Dim num1 As Integer Dim num2 As Integer Console.WriteLine("Enter first number: ") num1 = Console.ReadLine() Console.WriteLine("Enter second number: ") num2 = Console.ReadLine() If num1 > num2 Then Console.WriteLine("Number 1 is greater than number 2") Else Console.WriteLine("Number 2 is greater than number 3") End If

End Sub

End Module


If else/ elseif / else

If num1 > num2 Then Console.WriteLine("Number 1 is greater than number

2!") ElseIf (num2 > num1) Then Console.WriteLine("Number 1 is greater than number

2!") Else Console.WriteLine("Number are equal!") End If


Example 4

• VB.net\LaboratoryExercise\IFCondition\ifCondition


While Repetition Structure

• A repetition structure allows the programmer to specify that an action should be repeated depending on the value of the condition


Do while/Loop

Module WhileLoop Dim ctr As Integer Sub Main() ctr = 1 While ctr <= 10 ctr = ctr + 1 Console.WriteLine(ctr) End While End Sub

End Module


Do Until/Loop Repetition

• Test a condition for falsity for repetition to continue. Statements in the body of a are executed repeatedly as long as the loop-continuation test evaluates to false


Module DoWhileLoop Dim ctr As Integer Sub Main() ctr = 10 Do Until ctr < 1 Console.WriteLine(ctr) ctr = ctr - 1 Loop

End Sub

End Module


Assignment Operators

+= C=+7 C = c +7

-= C-=7 C = c - 7

*= C*=7 C = c * 7

/= c/=7 C = c /7

\= c\=7 C = c \ 7

^= C^=7 C = c ^ 7

&= D &= “llo” D= D & “llo”


Module Module1

Sub Main() Dim a As Integer Dim var1 As Integer Dim sum As Integer a = 1 sum = 0 While a <= 10 Console.WriteLine("Enter Number " & a & ":") var1 = Console.ReadLine() a += 1 sum = var1 + sum End While Console.WriteLine("The sum is " & sum) End Sub

End Module


For/Next Repetition

• Repetition structure handles the details of counter-controlled repetition.


Module ForLoop

Sub Main() Dim counter As Integer

For counter = 1 To 10 Console.WriteLine(counter) Next End Sub

End Module


Using Dialog to Display Message

• On the solution explorer, right click on the reference and add System.windows.forms


Message box

• MessageBox.Show("Text", "Title Bar caption", MessageBoxButtons.OK, MessageBoxIcon.Hand, MessageBoxDefaultButton.Button1, MessageBoxOptions.RightAlign)


Work Space

• Form – Gray rectangle which represents the Windows Applications that the programmer is creating

• The form which is the visual part of the program which the user interact


Introduction to Windows Application Program

• Messagebox

MesageboxIcon.Information

MessageBox.OK

Title Bar Text

Message Text


• MessageBoxIcon.Exclamation – Excalmation Point• MessageBoxIcon.Information – Icon Containing the letter I• MessageBoxIcon.Question – Icon Containing question mark• MessageBoxIcon.Error – Icon containing the red x circle


• MessageBoxButtons.OK – OK button• MessageBoxButtons.OKCancel – OK and Cancel

buttons• MessageBoxButtons.YesNo – Yes and No Buttons• MessageBoxButtons.YesNoCancel – Yes, no and

cancel buttons• MessageBoxButtons.RetryCancel – Retry and

Cancel Button


Select Case Multiple-Selection Structure

Select Case variableCase <decision 1>

CodeCase <decision 2>

CodeCase Else

CodeEnd Select


Module SelectCaseModule Sub Main() Dim choys As Integer Console.WriteLine("Enter Choice") choys = Console.ReadLine

Select Case choys Case 1 Console.WriteLine(1) Case 2 Console.WriteLine(2) Case Else Console.WriteLine("Default") End Select End Sub

End Module


Exit Keyword in a Repetition

• Exit Do, Exit While, Exit For statements alter the flow of control by causing immediate exit from a repetition structure


• Exit Do – Exit a do while repetition• Exit for – Exit a for loop• Exit While – Exit a while repetition


Logical Operators

• Visual Basic provides logical operators that can be used to form complex conditions by combining simple ones


• AndAlso• And• OrElse• Or• Xor• Not


AndAlso

• False + False = False• False + True = False• True + False = False• True + True = True


OrElse

• False + False = False• False + True = True• True + False = True• True + True = True


Not

• True = False• True = False


Xor

• False + False = False• False + True = True• True + False = True• True + True = False


Sub Procedures

Module SubProc Sub Main() Dim choys As Integer Console.WriteLine("Enter Choice") choys = Console.ReadLine

Select Case choys Case 1 proc1("jpacs")

End Select End Sub

Sub proc1(ByVal name As String) Console.WriteLine(name) End SubEnd Module


Procedure

• Similar to sub procedure except that function procedures return a value

Function procedure-name(parameter list) as return typeDeclarations and Statement

End Function


Maximum

• Get the maximum value of two number– Math.Max(val1, val2)


Public Class frmMax Inherits System.Windows.Forms.Form Dim val1, val2, val3 As Double

Private Sub cmdMax_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdMax.Click

val1 = txtFirst.Text val2 = txtSecond.Text val3 = txtThird.Text

lblTotal.Text = Math.Max(Math.Max(val1, val2), val3)

End SubEnd Class


More Math Functions

• Abs(x) – returns absolute value of x• Ceiling(x) – rounds x to the smallest integer• Cos(x) returns the trigonometric cosine


• Exp(x) – returns the exponential ex

• Floor(x) – rounds x to the largest integer not greater than x

• Log(x) – returns the natural logarithm of x (base e)

• Max(x,y) – returns the larger value of x and y

• Min(x,y) – returns the smallest value of x and y


• Pow(x,y) – Calculates x reaised to power y(xy)• Sin(x) – returns the trigonometric sine of x(x in radians)• Sqrt(x) – returns the square root of x• Tan(x) – returns the trigonometric tangent of x (x in radians)


• Random– Dim randomObject as Random = New Random()– Dim randomNumber as Integer = randomObject.Next()


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim randomObject As Random = New Random Dim randomNumber As Integer

randomNumber = randomObject.Next(1, 10) lblRandom.Text = randomNumber End Sub


Modules

• Programmers use modules to group related procedures so that they can be reused in other projects


How to add modules

• Goto File > Add new item• On the template select module


Module Module1 Function reuse(ByVal lbl As Label) lbl.Text = "jpacs" End FunctionEnd Module


Convert

• Use to convert variables or value on a desired data type• Example

– Convert.ToString (val2)– Convert.ToChar(1)


Array

• Can store information and has indexes or memory address• Array have the same name and same type• The first element of an array is 0th Element• The position on the array is called index


Public Class Form1Inherits System.Windows.Forms.FormDim numarray(10) As Integer

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

numarray(0) = 1 Label1.Text = numarray(0)

End SubEnd Class


GUI

• Label – An area in which icons or un editable text is displayed

• Textbox – An area in which the user inputs data from the keyboard. This can also display information

• Button – An area that triggers an event when clicked

• CheckBox – A component that is either selected on unselected


• ComboBox – A drop-down list of items from which the user can make a selection either by clicking an item in the list or by typing into a box

• ListBox – An area in which a list of items is displayed. The user can make a selection from the list by clicking on any item. Multiple elements can be selected.


• Panel – A container in which components can be placed• Scrollbar – A component that allows the user to access a range of

elements that normally cannot fit in the control’s container


Toolbox

• Contains all the windows forms and components• To add a component on a form, select the component on the

toolbox and drag it on the form


Unload a form

• Application.exit


Form Properties and Events

• AcceptButton – Button that is clicked when Enter is pressed

• AutoScroll – Boolean value that allows or disallows scrollbars to appear when needed

• CancelButton – Button that is clicked when the Escape key is pressed

• FormBorderStyle – Border style for the form (e.g., none, single, 3d)


• Font – font of text displayed on the form, and the default font of controls added to the form

• Text – Text in the form’s title bar


Common Methods

• Close – Closes a form and releases all resources. A closed form cannot be open.

• Hide – Hides form• Show – Display hidden forms


Code

• formName.ActiveForm.Close()


Textbox

• Passing a value:– txtEmpNoOut.Text = txtEmpNo.Text– txtEmpNameOut.Text = txtLastName.Text & " " &

txtFirstName.Text


Mathematical Operator on Text Box

• txtPhilhealth.Text = Val(txtSalaryMain.Text) * 0.05

• txtTax.Text = Val(txtSalaryMain.Text) * 0.04• txtSSS.Text = Val(txtSalaryMain.Text) * 0.03


Combo Box

• Adding Items on runtime– ComboBox1.Items.Add("ABC")

• Clearing Items on runtime– ComboBox1.Items.Clear()


Properties of a combo box

• DropDownStyle – Dropdownlist, Dropdown, Simple• Items - use to insert all the choices on your combo box


Adding Items on Combo on runtime

• cmbChoice.Items.Add("ABC")

Clearing the items on the combo box• cmbChoice.Items.Clear()


Getting the items on a combo

• cmbChoice.Items.Item (index number)


Radio Button

• Allows a user to choose a options• Properties

– Check = combo box is selected (True = Selected, False = Un Selected)

– Text = Text displayed on option Button


Example GUI 1

• Calculator• Payroll System


Picture Boxes

• A picture box displays an image. The image, set by an object of class Image, can be a bitmap, a GIF, JPEG, icon or metafile format.


Picture Box Properties

• Image – sets the image to display in the Picture Box• SizeMode – Enumeration that controls image sizing and

positioning. StretchImage, AutoSize and Center Image)


• Normal places the image in top-left corner of picture box

• CenterImage puts the image in middle (both truncate image if it is too large)

• StretchImage resizes image to fit in PictureBox.

• AutoSize resizes PictureBox to hold image


Loading Picture on Runtime

• picOne.Image = Image.FromFile("D:\VB.net\LaboratoryExercise\Picture Swapper\Pictures\Pic2.jpg")


Selecting the Current directory or Path

• .fromfile (directory.GetCurrentDirectory)


Example GUI 2

• Picture Swapper


List Box

• Allows the user to view and select from multiple items in a list


List Box Properties

• Items – Collection of an item in a listbox• SelectedIndex – Returns the index of the selected item. If selected

multiple items, the property returns arbitrary returns one of the selected indeces. If no items are selected, the property returns to -1


• SelectedIndeces – Returns a collection containing the indeces for all selected items

• SelectedItem – Returns a reference to the selected item (If multiple items are selected, it returns the items with the lowest number of index)

• SelectedItems – Returns a collection of selected items


• SelectionMode – Determines the number of items that can be selected– Values(None, One, Multiple)

• Sorted – Indicates whether items are sorted alphabetically


Adding of Item

• listOrder.Items.Add(“Item to Add”)


Removing of items

• listOrder.Items.Clear()

• Counting of items on a list– listOrder.Items.Count


CheckedListBoxes

• Control derives from Listbox but contains checkbox before each item


Properties

• CheckedItems – Contains the collection of items that are checked

• CheckedIndeces – Returns all indexes for checked items

• SelectionMode – Determines how many items can be checked. One(Multiple) and None(Does not allow)


To get checked item

tmp = listOrder.GetItemChecked(ctr - 1) If tmp = True Then listOrder.Items.RemoveAt(ctr - 1) End If


Remove item

• listOrder.Items.RemoveAt(ctr - 1)


Example GUI 3

• Font Browser• POS


Creating Shapes

• Import System.Drawing on your program


Imports System.DrawingPublic Class frmShapes Dim mygraphics As Graphics = MyBase.CreateGraphics Dim mypen As New Pen(Color.DarkRed)

Private Sub cmbShapes_SelectedIndexChanged_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbShapes.SelectedIndexChanged

If cmbShapes.Text = "Ellipse" Then mygraphics.Clear(Color.White) mygraphics.DrawEllipse(mypen, 100, 100, 100, 10) End If End SubEnd Class


Ellipse

• mygraphics.DrawEllipse(color of pen, x, y, height, width)


Tree View

• Displays nodes hierarchically in a tree.• Nodes are objects that contain values and can refer to other nodes• Parent node can contain child nodes• A child node can be a parent node to other nodes


• First node on the tree is the root node• Two child nodes are called siblings node


Properties of Tree View

• Checkboxes – Indicates whether a checkboxes appear next to node

• ImageList – Specifies ImageList containing the node icon• Nodes – List the collection of TreeNode, in the control


Methods on Treeview.Node

• Add (Adds a tree node object)• Clear (Clears the entire collection of tree node)• Remove (Delete a specific node)


Code

Public Class frmTree Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e

As System.EventArgs) Handles btnAdd.Click Dim StudName As String StudName = txtLName.Text + ", " + txtFName.Text + " " +

txtMI.Text If cmbCourse.Text = "ACT" Then treeStudents.Nodes(0).Nodes(0).Nodes.Add(StudName) End If End SubEnd Class


Font Properties

• New Font(Font,Size,Font Style)


Code

• Label1.Font = New Font("Comic Sans Serif", 14, FontStyle.Italic, GraphicsUnit.Pixel)


Checked box

• Small white square that either is blank or contains a checkmark. When a checkbox is selected, a blank checkmark appears in the box.


Properties of a checkbox

• Checked – Indicates whether the checkbox is checked or marked• CheckState – Indicates whether the checkbox is checked or

unchecked• Text – Specifies the text displayed to the right of the Checkbox

called label


Code

If chkBold.CheckState = CheckState.Checked Then txtOutput.Font = New Font(cmbFonts.Text, 12,

FontStyle.Bold)Else txtOutput.Font = New Font(cmbFonts.Text, 12,

FontStyle.Regular)End If


Common Dialog Box

• A rather tedious, but quite common, task in nearly every application is to prompt the user for filenames, font names and sizes, or colors to be used by the application


OpenFileDialog

• OpenFileDialog Lets users select a file to open. It also allows the selection of multiple files, for applications that must process many files at once (change the format of the selected files, for example).


Files and Streams

• Create Directory contains information about a directory– AppendText – Returns a StreamWriter that appends to an

existing file or creates a file if one does not exist


Database Programming using ADO.net

• Ado.net object model provides an API for accessing database systems programmatically.

• Was created for the .NET framework and is the next generation of ActiveX Data Objects (ADO), which was designed to interact with Microsoft’s Components Object Model (COM) framework


ADO.net

• simplify the code you write• allow you to bind graphical controls to DataSets


Primary Library of ADO.net

• System.data• System.data.OleDb• System.Data.SqlClient• System.Data.Dataset


Data Set

• uses the DataSet to store disconnected data


Adding OledbAdapter

• Click on Tools > Choose Toolbox Items • Click on .Net Framework Componets• Select OledbAdapter and Click OK


oleDbConnection

• The oleDbConnection object uses OLE DB to connect to a data source. ADO.NET

• also includes a new type of connection: SQLConnection


• Dim connString As String = _• “Provider= SQLOLEDB.1;Data Source=localhost;” & _• “uid=sa;pwd=;Initial Catalog=northwind;”• Dim myConn As New oleDbConnection()• myConn.ConnectionString = connString• myConn.Open()


Example Database

• Dbase Application


• The End!!!!


Data Adapter Wizard

• New Connection– Data Source – Database Connection– Database File Name – File Name of the database

• Change the Datasource– Microsoft Access Database File– Click Ok– Find the Access File– Test the connection


Continuation

• Click OK• Choose Use SQL Statements• Insert your SQL • Click Finish


More…

• You will be returned at the design tab• There are two components that has been added:

– oleDbDataAdapter1

– oleDbConnection1


• The oleDbConnection1 control describes the database connection;• The oleDbDataAdapter1 control describes your actual query• In VB.NET, the object you use to store data is called a DataSet.


Data Set

• Click once on the form. • Notice that on the menu bar, a new menu item has appeared:

DataSet• Drag the DataSet on the form• Select untype data sets

Visual Basic .Net

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