Visual basics

June 21, 2017 www.snipe.co.in 1
Prepared by: snipe team

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Microsoft Visual Basic 6.0

1. Introduction To VB
2. Programming in VB
3. The Form Object And Controls
4. Sample Programs
5. Database Connectivity
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Agenda

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Visual Basic (VB) is an ideal programming language for developing sophisticated
professional applications for Microsoft Windows.
It makes use of Graphical User Interface for creating robust and powerful applications.
The Graphical User Interface as the name suggests, uses illustrations for text, which
enable users to interact with an application. This feature makes it easier to comprehend
things in a quicker and easier way
In GUI environment, the number of options open to the user is much greater, allowing
more freedom to the user and developer. Features such as easier comprehension, user-
friendliness, faster application development and many other aspects such as
introduction to ActiveX technology and Internet features make Visual Basic an
interesting tool to work with.
Visual Basic (VB) was developed from the BASIC programming language. In the
1970s, Microsoft started developing ROM-based interpreted BASIC for the early
microprocessor-based computers. In 1982, Microsoft QuickBasic revolutionized Basic
and was legitimized as a serious development language for MS-DOS environment.
Later on, Microsoft Corporation created the enhanced version of BASIC called Visual
Basic for Windows.
Introduction To VB

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Introduction To VB
Important Features of Visual Basic (VB)
• Full set of objects .
• Lots of icons and pictures for to use
• Response to mouse and keyboard actions
• Clipboard and printer access
• Full array of mathematical, string handling, and graphics functions
• Can handle fixed and dynamic variable and control arrays
• Sequential and random access file support
• Useful debugger and error-handling facilities
• Powerful database access tools
• ActiveX support
• Package & Deployment Wizard makes distributing your applications simple

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Introduction To VB
Getting Started with Visual Basic 6.0
You will find Microsoft Visual Basic 6.0 on your Start > Programs menu
"First Choice": New | Existing | Recent
See the different choices under each:
• New
Create a new project allows selection of new project from Templates and
Wizards
• Existing
•Browse for existing VB project files
• Recent
The most recent projects opened in VB6

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Continued…
NEW PROJECT OPTIONS
• Standard EXE
Typically used for standard applications
Loads with the intrinsic VB6 controls in the toolbox
Loads a new project with a single form
•ActiveX EXE or ActiveX DLL
Used to create objects used by (other) applications
No forms included, creates a single Class module
•ActiveX Control
Allows developing your own controls (that can be used on forms I other
applications)
Loads with the intrinsic VB6 controls in the toolbox
Loads a new project with a single form-like UserControl module
•VB Application Wizard
Based on user selections, VB creates a skeleton application ready for entering code
to handle menu and button events, etc.

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Continued…
•Addin
Creates a project that runs as an add-in under the VB6 IDE
•Data Project
Creates a new project that contains a single Form, a DataEnvironment object and a
DataReport object.This project includes a number of references to support Data
Access and Data Binding.It also includes several additional controls in the toolbar

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A standard EXE project consist of the following windows
• Project Window
• Form Layout window
• Properties Window
• Form Designer window
• Immediate window
• Toolbox
Introduction To VB
VB Projects contains the following files
•Form files(.frm)
•Binary Files(.frx)
•Standard Modules(.bas)
•Class Modules(.cls)
•Project File (.vbp)
•ActiveX control file(.ocx)
•Resource file(.res)

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Title Bar Menu and Toolbar
Examples of custom toolbars
Opens the
different
windows
Run, Pause, Stop
Application debugging
Add project, Add "module", Menu editor
Left, Top Width, Height
Selection Coordinates
Introduction To VB

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The VB6 IDE
Introduction To VB

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Creating an Application
Create a new project. File -> New Project
Introduction To VB

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Select the required tools from the toolbox and place them
on the design form.
If your toolbox is not visible, select View->Toolbox.
Design Form
Introduction To VB

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Code Form
Introduction To VB

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Common Events
KeyBoard Events
•Keydown
•Keyup
•keyPress
Programming In VB
Mouse Events
•Click
•DblClick
•MouseDown
•Mouseup
•Mousemove
Visual Basic (VB) is an event-driven programming language. Visual Basic programs
are built around events. Events are various things that can happen in a program. this
will become clearer when studied in contrast to procedural programming. In procedural
languages, an application is written is executed by checking for the program logically
through the program statements, one after another. For a temporary phase, the control
may be transferred to some other point in a program. While in an event driven
application, the program statements are executed only when a particular event calls a
specific part of the code that is assigned to the event.

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Programming in VB
Variables:
Variables are the place holders used to store values during execution of a program
Declaring a variable tells Visual Basic to reserve space in memory. It is not must that
a variable should be declared before using it. Automatically whenever Visual Basic
encounters a new variable, it assigns the default variable type and value. This is called
implicit declaration. Though this type of declaration is easier for the user, to have
more control over the variables, it is advisable to declare them explicitly. The variables
are declared with a Dim statement to name the variable and its type. The As type clause
in the Dim statement allows to define the data type or object type of the variable. This
is called explicit declaration.
Declaring Variables
Examples:
Dim varname as Datatype
Dim age as integer
Dim name as string
Dim percent as double
Dim num1 as variant

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Programming in vb 6.0
Data Types

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Programming In VB
Type Casting
Myval = varType(argument)

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Scope And Life time of Variables
Constants
Syntax:
[Public|Private]Const constantname [As type] = expression
Examples:
Const conPi = 3.14159265358979 Public Const conMaxPlanets As Integer = 9
• System -Defined Constants:
These constants are usually prefixed with vb(lower case)
For example the value of a check box control may be 0 (Unchecked),1 (Checked),
2 (Grayed).
Check1.value=vbUnchecked
Check1.value=vbChecked
Check1.value=vbGrayed
• User Defined Constants
Syntax:
Const contant_name As type=value
Example:
Const PI as type Double=3.14159
Programming In VB

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Procedures in Visual Basic 6
Visual Basic programs can be broken into smaller logical components called
Procedures. Procedures are useful for condensing repeated operations such as the
frequently used calculations, text and control manipulation etc. The benefits of using
procedures in programming are:
•It is easier to debug a program a program with procedures, which breaks a program
into discrete logical limits.
•Procedures used in one program can act as building blocks for other programs with
slight modifications.
A Procedure can be Sub, Function or Property Procedure.
Programming In VB

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Programming In VB
Sub Procedures
A sub procedure can be placed in standard, class and form modules. Each time the
procedure is called, the statements between Sub and End Sub are executed. The syntax
for a sub procedure is as follows:
[Private | Public] [Static] Sub Procedurename [( arglist)]
[ statements]
End Sub
arglist is a list of argument names separated by commas. Each argument acts like a
variable in the procedure. There are two types of Sub Procedures namely general
procedures and event procedures.
Event Procedures
An event procedure is a procedure block that contains the control's actual name, an
underscore(_), and the event name. The following syntax represents the event procedure
for a Form_Load event.
Private Sub Form_Load()
....statement block..
End Sub
Event Procedures acquire the declarations as Private by default.

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General Procedures
A general procedure is declared when several event procedures perform the same
actions. It is a good programming practice to write common statements in a separate
procedure (general procedure) and then call them in the event procedure.
In order to add General procedure:
The Code window is opened for the module to which the procedure is to be added.
The Add Procedure option is chosen from the Tools menu, which opens an Add
Procedure dialog box as shown in the figure given below.
The name of the procedure is typed in the Name textbox
Under Type, Sub is selected to create a Sub procedure, Function to create a Function
procedure or Property to create a Property procedure.
Under Scope, Public is selected to create a procedure that can be invoked outside the
module, or Private to create a procedure that can be invoked only from within the
module.
Programming In VB

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Programming In VB

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Function Procedures
Functions are like sub procedures, except they return a value to the calling procedure.
They are especially useful for taking one or more pieces of data, called arguments and
performing some tasks with them. Then the functions returns a value that indicates the
results of the tasks complete within the function.
The following function procedure calculates the third side or hypotenuse of a right
triangle, where A and B are the other two sides. It takes two arguments A and B (of
data type Double) and finally returns the results.
Function Hypotenuse (A As Double, B As Double) As Double
Hypotenuse = sqr (A^2 + B^2)
End Function
Property Procedures
A property procedure is used to create and manipulate custom properties. It is used to
create read only properties for Forms, Standard modules and Class modules.Visual
Basic provides three kind of property procedures-Property Let procedure that sets the
value of a property, Property Get procedure that returns the value of a property, and
Property Set procedure that sets the references to an object.
Programming In VB

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Operators
Programming In VB

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If...Then selection structure
Programming In VB

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Nested If...Then...Else selection structure
If < condition 1 > Then
statements
Else
statements
Else
statements
Else
Statements
End If
End If
EndIf
Example:
Assume you have to find the grade using
nested if and display in a text box
If average > 75 Then
txtGrade.Text = "A"
ElseIf average > 65 Then
txtGrade.Text = "B"
txtGrade.text = "C"
txtGrade.Text = "S"
Else
txtGrade.Text = "F"
End If
Programming In VB

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Select...Case selection structure
Syntax:
Select Case Index
Case 0
Statements
Case 1
Statements
End Select
Example:
Assume you have to find the grade using
select...case and display in the text box
Dim average as Integer
average = txtAverage.Text
Select Case average
Case 100 To 75
txtGrade.Text ="A"
Case 74 To 65
txtGrade.Text ="B"
Case 64 To 55
txtGrade.Text ="C"
Case 54 To 45
txtGrade.Text ="S"
Case 44 To 0
txtGrade.Text ="F"
Case Else
MsgBox "Invalid average marks"
End Select
Programming In VB

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Do While... Loop Statement
The Do While...Loop is used to execute statements until a certain condition is met. The
following Do Loop counts from 1 to 100.
Dim number As Integer
number = 1
Do While number <= 100
number = number + 1
Loop
While... Wend Statement
A While...Wend statement behaves like the Do While...Loop statement. The following
While...Wend counts from 1 to 100
Dim number As Integer
number = 1
While number <=100
number = number + 1
Wend
Programming In VB

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Do...Loop While Statement
The Do...Loop While statement first executes the statements and then test the condition
after each execution. The following program block illustrates the structure:
Dim number As Long
number = 0
Do
number = number + 1
Loop While number < 201
Do Until...Loop Statement
Programming In VB

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The For...Next Loop
Programming In VB

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An array is a consecutive group of memory locations that all have the same name and
the same type. To refer to a particular location or element in the array, we specify the
array name and the array element position number.
Arrays
There are two types of arrays in Visual Basic namely:
iFixed size array : The size of array always remains the same-size doesn't change during the
program execution.
Dim numbers(5) As Integer
The following statement declares a two-dimensional array 50 by 50 array within a procedure.
Dim AvgMarks ( 50, 50)
It is also possible to define the lower limits for one or both the dimensions as for fixed size
arrays. An example for this is given here.
Dim Marks ( 101 To 200, 1 To 100)
An example for three dimensional-array with defined lower limits is given below.
Dim Details( 101 To 200, 1 To 100, 1 To 100)
Dynamic array : The size of the array can be changed at the run time- size changes during the
program execution.
Programming In VB

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User Defined Data Type
Programming In VB

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A User-Defined data type can be referenced in an application by using the variable
name in the procedure along with the item name in the Type block. Say, for example if
the text property of a TextBox namely text1 is to be assigned the name of the electronic
good, the statement can be written as given below.
Text1.Text = ElectronicGoods.ProdName
If the same is implemented as an array, then the statement becomes
Text1.Text = ElectronicGoods(i).ProdName
User-defined data types can also be passed to procedures to allow many related items
as one argument.
Sub ProdData( ElectronicGoods as ProductDetails)
Text1.Text = ElectronicGoods.ProdName
Text1.Text = ElectronicGoods.Price
End Sub
Programming In VB

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Visual Basic Built-in Functions
Many built-in functions are offered by Visual Basic fall under various categories.
These functions are procedures that return a value. The functions fall into the following
basic categories.
•Date and Time Functions
•Format Function
•String Functions
Programming In VB

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Input Box
Displays a prompt in a dialog box, waits for the user to input text or click a button,
and returns a String containing the contents of the text box.
Syntax :
memory_variable = InputBox (prompt[,title][,default])
memory_variable is a variant data type but typically it is declared as string, which
accept the message input by the users. The arguments are explained as follows:
Prompt - String expression displayed as the message in the dialog box. If prompt
consists of more than one line, you can separate the lines using the vbCrLf constant
Title - String expression displayed in the title bar of the dialog box. If you omit the
title, the application name is displayed in the title bar
default-text - The default text that appears in the input field where users can use it as
his intended input or he may change to the message he wish to key in.
x-position and y-position - the position or the coordinate of the input box.
Programming In VB

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Message Box
Displays a message in a dialog box and wait for the user to click a button, and
returns an integer indicating which button the user clicked.
Syntax :
MsgBox ( Prompt [,icons+buttons ] [,title ] )
memory_variable = MsgBox ( prompt [, icons+ buttons] [,title] )
Prompt : String expressions displayed as the message in the dialog box. If prompt
consist of more than one line, you can separate the lines using the vbrCrLf constant.
Icons + Buttons : Numeric expression that is the sum of values specifying the
number and type of buttons and icon to display.
Title : String expression displayed in the title bar of the dialog box. If you omit title,
the application name is placed in the title bar.
Programming In VB

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Programming In VB
Types and values of MsgBox Buttons

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The Form Object And Controls
A Form is container or a window consisting if all elements or controls that make up the
user interface.
A control is an object that can be drawn on a Form object to enable or enhance user
interaction with an application. Controls have properties that define aspects their
appearance, such as position, size and colour, and aspects of their behavior, such as
their response to the user input. They can respond to events initiated by the user or set
off by the system.
For instance, a code could be written in a CommandButton control's click event
procedure that would load a file or display a result.
In addition to properties and events, methods can also be used to manipulate controls
from code. For instance, the move method can be used with some controls to change
their location and size.

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Intrinsic Controls

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Designing Menus
Visual Basic provides an easy way to create menus with the modal Menu Editor dialog.
The below dialog is displayed when the Menu Editor is selected in the Tool Menu. The
Menu Editor command is grayed unless the form is visible. And also we can display
the Menu Editor window by right clicking on the Form and selecting Menu Editor.

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The Multiple Document Interface (MDI) :
MDI form acts as a container for other forms in the application.
To create an MDI application, follow these steps:
•Start a new project and then choose Project >>> Add MDI Form to add the
parent Form.
•Set the Form's caption to MDI Window
•Choose Project >>> Add Form to add a SDI Form.
•Make this Form as child of MDI Form by setting the MDI Child property of
the SDI Form to True. Set the caption property to MDI Child window.

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Sample Programs
Program to add two numbers
Step 1: Design the form using controls

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Sample Programs
Step 2: Open the code window and write the code

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Sample Programs
Step 3:Run the project

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Database Connectivity
A database is a collection of data that is related one to another to support a common
application.
For example Employee details - Name, Address, etc. Each of these collections of data
continue a database.
The database accessing methods are as follows:
1) Jet Engine - Accessing Microsoft Access and Visual Basic databases.
2) ODBC (Open Database Connectivity) - Allow access to the client server databases
on a network.
3) ISAM (Index Sequential Access Method) - Used to access flat databases such as
dBase, FoxPro, ParaDox.

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ADO (ActiveX Data Object) data control
• The ADO (ActiveX Data Object) data control is the primary interface between a
Visual Basic application and a database. It can be used without writing any code at all!
Or, it can be a central part of a complex database management system. This icon may
not appear in your Visual Basic toolbox. If it doesn’t, select Project from the main
menu, then click Components. The Components window will appear. Select Microsoft
ADO Data Control, then click OK. The control will be added to your toolbox.
• When a data control is placed on a form, it appears with the assigned caption and four
arrow buttons.

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• The data control can be used to perform the following tasks:
1. Connect to a database.
2. Open a specified database table.
3. Create a virtual table based on a database query.
4. Pass database fields to other Visual Basic tools, for display or editing. Such
tools are bound tools (controls), or data aware.
5. Add new records or update a database.
6. Trap any errors that may occur while accessing data.
7. Close the database.

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• Data Control Properties:
Align Determines where data control is displayed.
Caption Phrase displayed on the data control.
ConnectionString Contains the information used to establish a connection to a
database.
LockType Indicates the type of locks placed on records during editing
(default setting makes databases read-only).
Recordset A set of records defined by a data control’s ConnectionString
and RecordSource properties. Run-time only.
RecordSource Determines the table (or virtual table) the data control is
attached to.

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Thank You

Visual basics

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