introduction vb

8/6/2019 Introduction VB

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Object 9 : About GUI and Visual Basic

Visual Basic 6.0

Introduction

An integrated development environment (IDE), also known as integrated design environmentand integrated debugging environment, is a type of computer software that assists computer

programmers to develop software.

IDE Contents

The Visual Studio IDE consists of several sections, or tools, that the developer uses while

programming. As you view the IDE for a new project you generally have three sections in view:

The Toolbox on the left The Solution Explorer on the right The Code / Design view in the middle

Toolbox

The Toolbox is a palette of developer objects, or controls, that are placed on forms or web

pages, and then code is added to allow the user to interact with them. An example would be

TextBox, Button and ListBox controls. With these three controls added to a Windows Form

object the developer could write code that would take text, input by the application user, and

added to the ListBox after the button was clicked.

Solution Explorer

This is a section that is used to view and modify the contents of the project. A Visual StudioWindows Application Project will generally have a Form object with a code page, references to

System components and possibly other modules with special code that is used by the

application.

Properties Windows

The properties windows shows all the control (like textbox) properties to be change at design

time. Most of these properties can be change at run time with some code, but basically most of

this properties change the way the control is display on your application.

Code / Design view

This is where the magic takes place. Forms are designed graphically. In other words, the

developer has a form on the screen that can be sized and modified to look the way it will be

displayed to the application users. Controls are added to the form from the Toolbox, the color

and caption can be changed along with many other items.

This center window of the IDE is also where developers write the code that makes everything in

the application work. The code is written in modules, or files, that are either connected to an

object (Forms) or called specifically when needed.


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A brief description of Visual Basic

VISUAL BASIC is a high level programming language evolved from the earlier DOS version called

BASIC. BASIC means Beginners' All purpose Symbolic Instruction Code. It is a fairly easy

programming language to learn. The codes look a bit like English Language. Different software

companies produced different version of BASIC, such as Microsoft QBASIC, QUICKBASIC,

GWBASIC ,IBM BASICA and so on.

VISUAL BASIC is a VISUAL and events driven Programming Language. These are the main

divergence from the old BASIC. In BASIC, programming is done in a text-only environment and

the program is executed sequentially. In VISUAL BASIC, programming is done in a graphical

environment. Because users may click on a certain object randomly, so each object has to be

programmed independently to be able to response to those actions (events).Therefore, a

VISUAL BASIC Program is made up of many subprograms, each has its own program codes, and

each can be executed independently and at the same time each can be linked together in one

way or another.


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Introduction to Forms

Forms are the first Microsoft Visual Basic objects you get acquainted with. Although you canwrite useful programs with only rudimentary user interfacescommand-line driven utilities, for

examplemost Visual Basic applications include one or more forms, and so you need to be

familiar with their properties and features.

Intrinsic Controls

TextBox Controls

TextBox controls offer a natural way for users to enter a value in your program. For this reason,

they tend to be the most frequently used controls in the majority of Windows applications.

TextBox controls, which have a great many properties and events, are also among the mostcomplex intrinsic controls. In this section, I guide you through the most useful properties of

TextBox controls and show how to solve some of the problems that you're likely to encounter.

Label Controls

Most people use Label controls to provide a descriptive caption and possibly an associated hot

key for other controls, such as TextBox, ListBox, and ComboBox, that don't expose the Caption


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property. In most cases, you just place a Label control where you need it, set its Caption

property to a suitable string (embedding an ampersand character in front of the hot key you

want to assign), and you're done. Caption is the default property for Label controls.

CommandButton Controls

Using CommandButton controls is trivial. In most cases, you just draw the control on the form's

surface, set its Caption property to a suitable string (adding an & character to associate a hot

key with the control if you so choose), and you're finished, at least with user-interface issues. To

make the button functional, you write code in its Clickevent procedure, as in this fragment:

Private Sub Command1_Click()

' Save data, then unload the current form.

Call SaveDataToDisk

Unload Me

End Sub

CheckBox Controls

CheckBox controls are useful when you want to offer your users a yes or no, true or false choice.

Anytime you click on this control, it toggles between the yes state and the no state.

OptionButton Controls

OptionButton controls are also known as radio buttons because of their shape. You always use

OptionButton controls in a group of two or more because their purpose is to offer a number of

mutually exclusive choices. Anytime you click on a button in the group, it switches to a selected

state and all the other controls in the group become unselected

ListBox Controls

ComboBox Controls


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Object 10 -Design a program to display regional languages of different states in India.

Take many names of status of India in one list box control and other text box control

should display their languages e. g. Maharashtra Marathi etc.

Code

Private Sub Form_Load()

List1.text=

Text1.text=

Label1.caption=Select Language

Label2.caption=State

List1.AddItem ("Hindi")

List1.AddItem ("Marathi")

List1.AddItem ("Telgu")

List1.AddItem ("Orria")

List1.AddItem ("Kannnada")List1.AddItem ("Malyalam")

List1.AddItem ("Gujrati")

End Sub

Private Sub List1_Click()

Dim i As Integer

If List1.ListIndex = -1 Then


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Exit Sub

For i = List1.ListCount - 1 To 0 step -1

If List1.Selected(i) = True Then

If List1.List(i) = "Hindi" Then

Text1.Text = "MP, Delhi"

ElseIf List1.List(i) = "Marathi" Then

Text1.Text = "Maharastra"

ElseIf List1.List(i) = "Telgu" Then

Text1.Text = "Andra Pradesh"

ElseIf List1.List(i) = "Orria" Then

Text1.Text = "Orrisa"

ElseIf List1.List(i) = "Kannnada" Then

Text1.Text = "Karanataka"

ElseIf List1.List(i) = "Malyalam" Then

Text1.Text = "Kerla"

ElseIf List1.List(i) = "Gujrati" ThenText1.Text = "Gujrat"

End If

End If

Next i

End Sub

Data Types in Visual Basic 6.0

There are many types of data we come across in our daily life. For example, we need to handledata such as names, adresses, money, date, stock quotes, statistics and etc everyday. Similarly In

Visual Basic, we are also going to deal with these kinds of data. However, to be more systematic,

VB divides data into different types.

Numeric DataTypes

Numeric data are data that consists of numbers, which can be computed mathematically with

various standard operators such as add, minus, multiply, divide and so on. In Visual Basic, the

numeric data are divided into 7 types.

Type Storage Range of Values

1)Byte 1 byte 0 to 255

2)Integer 2 bytes -32,768 to 32,767

3)Long 4 bytes -2,147,483,648 to 2,147,483,648

4)Single 4 bytes -3.402823E+38 to -1.401298E-45 for negative values

1.401298E-45 to 3.402823E+38 for positive values.

5)Double 8 bytes -1.79769313486232e+308 to -4.94065645841247E-324 for negative

4.94065645841247E-324 to 1.79769313486232e+308 for positive values.

6)Currency 8 bytes -922,337,203,685,477.5808 to 922,337,203,685,477.5807

7)Decimal 12 bytes +/- 79,228,162,514,264,337,593,543,950,335 if no decimal is use


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+/- 7.9228162514264337593543950335 (28 decimal places).

Nonnumeric Data Types

Data Type Storage Range

1)String(fixed length) Length of string 1 to 65,400 characters

2)String(variable length) Length + 10 bytes 0 to 2 billion characters

3)Date 8 bytes January 1, 100 to December 31, 9999

4)Boolean 2 bytes True or False

5)Object 4 bytes Any embedded object

6)Variant(numeric) 16 bytes Any value as large as Double

7)Variant(text) Length+22 bytes Same as variable-length string

Suffixes for Literals

Literals are values that you assign to a data. In some cases, we need to add a suffix behind a

literal so that VB can handle the calculation more accurately. For example, we can usenum=1.3089# for a Double type data.

Suffix Data Type

& Long

! Single

# Double

@ Currency

In additon, we need to enclose string literals within two quotations and date and time literals

within two # sign. Strings can contain any characters, including numbers. The following are fewexamples:

memberName="Turban, John."

TelNumber="1800-900-888-777"

LastDay=#31-Dec-00#

ExpTime=#12:00 am#

The following are the rules when naming the variables in Visual Basic

It must be less than 255 characters

No spacing is allowed

It must not begin with a number

Declaring Variables

In Visual Basic, one needs to declare the variables before using them by assigning names and

data types. They are normally declared in the general section of the codes' windows using the

Dim statement.

The format is as follows:

Dim variableNmae as DataType


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Dim password As String

Dim yourName As String

Dim firstnum As Integer

Dim secondnum As Integer

Dim total As Integer

Dim doDate As Date

You may also combine them in one line , separating each variable with a comma, as follows:

Dim password As String, yourName As String, firstnum As Integer,.............

If data type is not specified, VB will automatically declares the variable as a Variant.

Create and save a new program

1. Start VB.Find Visual Basic on the Windows Start menu and start it.

The large VB window appears with a New Project dialog box (if there is no dialog box,

bring it up by File > New Project).

Select Standard Exe. The VB window shows Project1 with an empty Form1.

2. Name the project.Select Project > Project1 Properties. In the Project Properties dialog box, change

Project1 to your project name, say Counter.

The title bar on the VB window changes to match.

3. Name the form and set the form caption.The Properties window at the right of the VB window shows the properties for the form.

The first property at the top of the list is Name. Change the name to, say, frmCounter.

The title bar in the Form window changes to match.

Still in the Properties window, scroll down to Caption. Change the caption to the same

name as the project, say Counter.

The title bar on the form itself changes to match.

4. Save the form (you should always name and save the form before you save the project).Select File > Save frmCounter As .... The Save Form As dialog box appears. The Save in:

textbox shows the name of the folder where the form will be saved. You should create a

new folder for this project. Navigate to the folder where you want to keep all your VB

projects and click on the new folder icon (a picture of a folder with a little highlight).

After you create the new folder, select that folder. Its name should appear in the Save


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in: box. The form file name frmCounter.frm should appear in the File name: box (if not,

type in the correct name). Click on Save.

The form is saved.

5. Save the project (be sure to name and save the form before you save the project).Select File > Save Project As .... The Save Project As dialog box appears. The Save in:

textbox should show the correct folder (the one you just created for the form). The File

name: box should show the correct name (Counter.vbp in this example). Click on Save.

The project is saved.

After you name and save the form and the project, it is a good idea to exit and then restart VB to

make sure you can restore your project --- before you invest a lot of work in it.

Restore a saved program

1. Start VB.Find Visual Basic on the Windows Start menu and start it.

The large VB window appears with a New Project dialog box. This time choose the

Existing tab (if there is no dialog box, bring it up by File > Open Project).

Navigate to the folder you created earlier. It should contain a .vbp file for the project

you created earlier (Counter.vbp in this example). Select that file.

Alternatively, instead of using the Start menu, you can navigate to the project folder

using My Computer or Windows Explorer. Then double-clicking on the .vbp file or the.frm file starts VB and opens that project.

The restored project appears in the VB window. The project name appears in the title

bar.

2. Open the form.An icon for a folder of forms appears in the Project window on the right side of the VB

window. Open this folder and select the form you saved. Click on the View Code and

View Object icons to display the code or form layout windows.

Now you are ready to add controls and code to the form. At any time, you can use File >

Save frmCounter and File > Save Project to save your changes to the form and the

project without going through the Save As ... dialogs.

Write a program based on an earlier program

1. Restore a saved VB program, as described in How to Restore ... above.2. It is a good idea to change the project name and the form name, as described in How to

Create ... above.


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3. Make changes in the program.4. Save the form and the project in a new folder, using Save As ... (not Save) as described

in How to Create ... above.

Make sure you save the changed program in a different folder. This is necessary to

ensure that the earlier program is preserved. Be sure to save the form first.

Add controls(tools) to the form

Repeat for each control:

1. Choose the control.In the Toolbox window at the left, point at a control icon. The name of the control (for

example, Label) will appear.

Double click on the control icon.

The control appears in the middle of the form layout window.

2. Position and size the control.In the Form Layout window, point at the center of the control. Drag control to the

position you want (hold down the left mouse button while you move the mouse).

To size the control, point at one of the little grab boxes at the sides and corners of the

control. Drag the side (or corner) to make the size you want.

It is best to set the properties for each control right after you select it and position it.

Set control properties

For each control:

1. Use the Properties window at the right.Select the control from the drop-down menu at the top of the Properties window. Or,

click on the control in the form layout window.

A table showing all the control properties appears, with property names in the left

column and property values in the right.

2. The first property is Name. Type in a meaningful name, using the naming conventions:frm... for forms, cmd... for command buttons, lbl... for labels, tmr... for timers etc.

3. Set the other properties. For command buttons, set alignment, caption and font. Forlabels, set alignment, caption, font, and (often) background color. For timers, set

interval. And so on.

Write code for event subroutines


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For each pertinent control and event:

Use the Code window. Find the relevant event subroutine.

For controller Ctlrand event Event, the subroutine is named Ctlr_Event, for example

cmdEnter_Click.

Double-clicking on the controller in the Form layout window puts the cursor at the pertinent

subroutine in the Code window.

Run the program

There are several ways to run your program:

Press the F5 key. On the VB menu bar, Run > Start On the VB toolbar, click the VB Run icon (the arrow)

The program window appears, looking much like the form you designed. The controls on the

window are active. While the program is running, it behaves like any other window on the

desktop: you can move it, minimize it, etc.

The indicator on the VB window title bar changes from design mode to run mode. Many items

in the VB window disappear during run mode and many menu and toolbar operations not

enabled.

Stop the program

There are several ways to stop your program:

In your program's window, click the Exit button or menu (if you provided one) In your program window's title bar, click the Close button (VB always provides one) On the VB menu bar, Run > Stop On the VB toolbar, click the VB Stop icon (the box)

The indicator on the VB window title bar changes from run mode to design mode. Items in the

VB window reappear, and menu and toolbar operations are enabled again.

Revise the program

In design mode, you can add or remove controls, change control properties and revise code.Your changes will be in effect when you run the program again.

It is not necessary to use the Save operations before your next program run. It is only necessary

to save before you exit VB.

Exit

There are several ways to exit VB.


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On the menu bar, File > Exit On the VB window title bar, click the Close button


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Object 11 Add two numbers.

Step1 : Create three text boxes ,Three Labels and one command button.

Step2: Open code window and write the following code.


Form1.Caption = "Addition"

Text1.Text = ""

Text2.Text = ""

Label1.Caption = "Enter the First Number"

Label2.Caption = "Enter the Secomnd Number"

Text3.Text = ""

Label3.Caption = "Result is:"

Command1.Caption = "Sum"

End Sub


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Step 3) Write code for addition of two numbers in code window.


Text3.Text = Val(Text1.Text) + Val(Text2.Text)

End Sub

Step 4) Run the pogram and as soon as we click on Sum button ,it will give summation of text1

and text 2 and gives result in text3 text box.

Note: Val converts text into numeric values. If we do not use val than it will concatenate

values of both text boxes.


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Object 12) Print the following :

0

1

2

34

5

6

7

8

9

10


Form1.Caption = "Addition"

Form1.Show

For i = 0 To 10

Print ( i)

Next i

End Sub


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Object 13 ) Make a simple Calculator for addition, subtraction ,multiplication and

division

Step1) Add three labels, three text boxes and four command buttons to the form

Step2) Write the following code in code window


Form1.Caption = "Calculator"

Text1.Text = ""

Text2.Text = ""

Text3.Text = ""

Label1.Caption = "Enter the first Number"

Label2.Caption = "Enter the Second Number"

Label3.Caption = "Result is"

Command1.Caption = "+"

Command2.Caption = "-"

Command3.Caption = "*"

Command4.Caption = "/"

End Sub

Step3) Add following code to command buttons events click()

Private Sub Command1_Click()Label3.Caption = "Sum is"

Text3.Text = Val(Text1.Text) + Val(Text2.Text)

End Sub


Label3.Caption = "Subtraction is "

Text3.Text = Text1.Text - Text2.Text

End Sub


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Label3.Caption = "Multiplication is"

Text3.Text = Text1.Text * Text2.Text

End Sub


Label3.Caption = "Division is"

Text3.Text = Text1.Text / Text2.Text

End Sub

Step5) Execute the program we will get this out put.

Step6) on pressing any command button we will get following output


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Object14) Demonstrate Drive list box, Directory list box and file list box

Step1) Add one drivelist box, directorylist box and one file list box to form.

Step2) Need to establish connection among these objects. So need to write the following code

in code window. Default event of all the objects are change(). As soon as we change our option

from any object,effect will be produced ot corresponding object.

Private Sub Dir1_Change()File1.Path = Dir1.Path

End Sub

Private Sub Drive1_Change()

Dir1.Path = Drive1.Drive

End Sub


Form1.Caption = "Demo"

End Sub

Step3) Run the program we will get this type of output.


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Object 15 )Database Connectivity

Visual basic provides database connectivity facility apart from the facility of user friendly

interface.

We can establish connection to any type of database like Oracle,MS Assess, MYSQL, excel sheet

etc.

This can be done in many ways(Data Environment etc) but following two are most widely used.

1) DAO (Data access Object)2) ADO (ActiveX data Object)

Object 6) Using DAO: Adding Data object in toolbox.

Step1) Add Data Object to form.

Step2) Add Data bound grid control(To show data in table format) to toolbox using

Project->Components->MicroSoftDatabound grid control sp3

Step3) Draw DBGRID to form.

Step4) Go to property of Data object and change the following properties

Database : AccessDatabaseName: C:\Program Files\Microsoft Visual Studio\VB98\BIBLIO.MDB

Recordsettype: 0-Table

Recordsource: Authors

Step5) Go to property of DBGRID and change the following property

Datasource: DATA1

Step6) Execute the program. We get the content of Author table in GRID.


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Note : We can run queries to perform specific tasks using different events.

Object7) Using ADO.

Step1) App Microsoft ADO data object and Datagrid control6.0(To view the content of table) .

Project->components->Microsoft ADO data control 6.0

Project->components->Microsoft DtaGrid Control6.0


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Step2) Draw both controls on form as follows.

Step3) Go to Control panel->administrative services->Datasource (ODBC)


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Note :ODBC acts as an interface between program and Database.

Click on Add button we get list of drivers. Choose any one as per need (Microsoft access

Driver(*. mdb)) and click finsh.

We get following window


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Choose appropriate data base by pressing select button and give any convenient name in Data

source name

For our convenience we have selected the data base : C:\Program Files\Microsoft Visual

Studio\VB98\BIBLIO.MDB

And have given Data source name as Demo.

We get the following window

Now ODBC has been established.


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Step4) again go to property window of ADODC and click connection string we get following

window

Select the second option and choose the demo from combo box.

Step4) Click on record source property we get following window

Choose command type as table format and choose table of database and press OK.

Step5) go to property of DATAGRIG and change the following properties

Datasource: ADODC1

Step6) Write the following code to change the caption of form.


Form1.Caption = "Database ADODC"


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End Sub

Step7)Execute the program .We get following output.

Note : We can run queries to perform specific tasks using different events. We can use

different database software also like Oracle,MYSQL etc.

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