vb.net lecture

Visual Basic .net

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

Visual Studio .netMicrosoft’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 changingHas 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 ProjectsVisual C# ProjectsVisual C++ ProjectsSetup and Deployment ProjectsVisual Studio Solutions


Visual Basic ProjectsWindows 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 ProgrammingConsole application – applications contain

only text outputVisual Basic console applications consist of

pieces called module


Changing the default ModuleClick on Project > Console PropertiesOn the startup object change the startup

object to your startup module


To run a programOn the menu bar press DebugClick start without debugging (F5 for

shortcut key)


Console ProgrammingPrinting a text

Consolse.Write(“String”)Console.WriteLine(“The text goes here!”)

Writeline position the text in the beginning of the next line


Example 1VB.net\LaboratoryExercise\PrintingText


VariablesStores data or information during program

executionHow to declare

Dim variable_Name as Data_TypeTo insert a value:

Dim variable_Name as Data_Type = Value


NoteBefore VB can use an object variable, it

must determine its type and perform the necessary conversions, if any.


Data TypesTypes of Variables

Numeric – Store Numbers


Arithmetic OperatorsAddition - +Subtraction - -Multiplication - *Division - /Division (Integer) \Modulus - ModExponentiation - ^


Example 2\VB.net\LaboratoryExercise\

ConsoleCalculator\ConsoleCalC


Character VariablesYou 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 stringDim string_varialble as string = “Value”


ConcatenationJoining of two or more stringsExampleDim string1 as string = “a”Dim string 2 as string = “b”

String1 & string2ab


Example 3VB.net\LaboratoryExercise\

StringManipulation\StringManipulation


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


If thenIf studentGrade>=60 then

Console.WriteLine(“Passed”)End If


Decision MakingIf/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 4VB.net\LaboratoryExercise\IFCondition\

ifCondition


While Repetition StructureA repetition structure allows the

programmer to specify that an action should be repeated depending on the value of the condition


Do while/LoopModule 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 RepetitionTest 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 RepetitionRepetition 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 MessageOn the solution explorer, right click on the

reference and add System.windows.forms


Message boxMessageBox.Show("Text", "Title Bar

caption", MessageBoxButtons.OK, MessageBoxIcon.Hand, MessageBoxDefaultButton.Button1, MessageBoxOptions.RightAlign)


Work SpaceForm – 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 ProgramMessagebox

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 buttonMessageBoxButtons.OKCancel – OK and Cancel

buttonsMessageBoxButtons.YesNo – Yes and No ButtonsMessageBoxButtons.YesNoCancel – Yes, no and

cancel buttonsMessageBoxButtons.RetryCancel – Retry and

Cancel Button


Select Case Multiple-Selection StructureSelect 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 RepetitionExit 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 repetitionExit for – Exit a for loopExit While – Exit a while repetition


Logical OperatorsVisual Basic provides logical operators that

can be used to form complex conditions by combining simple ones


AndAlsoAndOrElseOrXorNot


AndAlsoFalse + False = FalseFalse + True = FalseTrue + False = FalseTrue + True = True


OrElseFalse + False = FalseFalse + True = TrueTrue + False = TrueTrue + True = True


NotTrue = FalseTrue = False


XorFalse + False = FalseFalse + True = TrueTrue + False = TrueTrue + True = False


Sub ProceduresModule 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


ProcedureSimilar to sub procedure except that

function procedures return a valueFunction procedure-name(parameter list) as

return typeDeclarations and Statement

End Function


MaximumGet 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 FunctionsAbs(x) – returns absolute value of xCeiling(x) – rounds x to the smallest integerCos(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 xTan(x) – returns the trigonometric tangent of

x (x in radians)


RandomDim 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


ModulesProgrammers use modules to group related

procedures so that they can be reused in other projects


How to add modulesGoto File > Add new itemOn the template select module


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


ConvertUse to convert variables or value on a

desired data typeExample

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


Array

Can store information and has indexes or memory address

Array have the same name and same typeThe first element of an array is 0th ElementThe 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


GUILabel – An area in which icons or un editable

text is displayedTextbox – 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


ToolboxContains all the windows forms and

componentsTo add a component on a form, select the

component on the toolbox and drag it on the form


Unload a formApplication.exit


Form Properties and EventsAcceptButton – Button that is clicked when Enter is

pressedAutoScroll – Boolean value that allows or disallows

scrollbars to appear when neededCancelButton – Button that is clicked when the

Escape key is pressedFormBorderStyle – 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 MethodsClose – Closes a form and releases all

resources. A closed form cannot be open.Hide – Hides formShow – Display hidden forms


Code formName.ActiveForm.Close()


TextboxPassing a value:

txtEmpNoOut.Text = txtEmpNo.TexttxtEmpNameOut.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 BoxAdding Items on runtime

ComboBox1.Items.Add("ABC")Clearing Items on runtime

ComboBox1.Items.Clear()


Properties of a combo boxDropDownStyle – Dropdownlist, Dropdown,

SimpleItems - use to insert all the choices on your

combo box


Adding Items on Combo on runtimecmbChoice.Items.Add("ABC")

Clearing the items on the combo boxcmbChoice.Items.Clear()


Getting the items on a combocmbChoice.Items.Item (index number)


Radio ButtonAllows a user to choose a optionsProperties

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

Text = Text displayed on option Button


Example GUI 1CalculatorPayroll System


Picture BoxesA 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 PropertiesImage – sets the image to display in the

Picture BoxSizeMode – 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 2Picture Swapper


List BoxAllows the user to view and select from

multiple items in a list


List Box PropertiesItems – Collection of an item in a listboxSelectedIndex – 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 selectedValues(None, One, Multiple)

Sorted – Indicates whether items are sorted alphabetically


Adding of ItemlistOrder.Items.Add(“Item to Add”)


Removing of items listOrder.Items.Clear()

Counting of items on a listlistOrder.Items.Count


CheckedListBoxesControl derives from Listbox but contains

checkbox before each item


PropertiesCheckedItems – Contains the collection

of items that are checkedCheckedIndeces – Returns all indexes

for checked itemsSelectionMode – Determines how many

items can be checked. One(Multiple) and None(Does not allow)


To get checked itemtmp = listOrder.GetItemChecked(ctr - 1)

If tmp = True Then

listOrder.Items.RemoveAt(ctr - 1)

End If


Remove itemlistOrder.Items.RemoveAt(ctr - 1)


Example GUI 3Font BrowserPOS


Creating ShapesImport 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


Ellipsemygraphics.DrawEllipse(color of pen, x, y,

height, width)


Tree ViewDisplays nodes hierarchically in a tree.Nodes are objects that contain values and

can refer to other nodesParent node can contain child nodesA child node can be a parent node to other

nodes


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


Properties of Tree ViewCheckboxes – Indicates whether a

checkboxes appear next to nodeImageList – Specifies ImageList containing

the node iconNodes – List the collection of TreeNode, in

the control


Methods on Treeview.NodeAdd (Adds a tree node object)Clear (Clears the entire collection of tree

node)Remove (Delete a specific node)


CodePublic 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 PropertiesNew Font(Font,Size,Font Style)


CodeLabel1.Font = New Font("Comic Sans

Serif", 14, FontStyle.Italic, GraphicsUnit.Pixel)


Checked boxSmall 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 checkboxChecked – Indicates whether the checkbox

is checked or markedCheckState – Indicates whether the

checkbox is checked or uncheckedText – Specifies the text displayed to the

right of the Checkbox called label


CodeIf 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 BoxA 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


OpenFileDialogOpenFileDialog 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 StreamsCreate Directory contains information

about a directoryAppendText – Returns a StreamWriter that

appends to an existing file or creates a file if one does not exist


Database Programming using ADO.netAdo.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.netsimplify the code you writeallow you to bind graphical controls to

DataSets


Primary Library of ADO.netSystem.dataSystem.data.OleDbSystem.Data.SqlClientSystem.Data.Dataset


Data Setuses the DataSet to store disconnected

data


Adding OledbAdapterClick on Tools > Choose Toolbox Items Click on .Net Framework ComponetsSelect OledbAdapter and Click OK


oleDbConnectionThe oleDbConnection object uses OLE DB

to connect to a data source. ADO.NETalso 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 = connStringmyConn.Open()


Example DatabaseDbase Application


The End!!!!


Data Adapter WizardNew Connection

Data Source – Database ConnectionDatabase File Name – File Name of the

databaseChange the Datasource

Microsoft Access Database FileClick OkFind the Access FileTest the connection


ContinuationClick OKChoose Use SQL StatementsInsert your SQL Click Finish


More…You will be returned at the design tabThere 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 SetClick once on the form. Notice that on the menu bar, a new menu

item has appeared: DataSetDrag the DataSet on the formSelect untype data sets

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