Vb 6ch123

3 Cube Computer Institute – VB 6 Notes

CHAPTER 1
Introduction to Visual Basic 6.0

Visual basic is a high level programming language (HLL) developed from the BASIC programming
language.
VB programming is done in a graphical environment, also known as GUI (Graphical User Interface).
Visual Basic enables the user to design the user interface quickly by drawing and arranging the user
elements. The Window GUI defines how the various elements such as FORMS and CONTROLS look
and function.
Visual Basic is an event-driven programming language.

Procedural vs. OOP vs. event-driven programming language

In the Procedural languages such as Basic, C, COBOL, etc the program specifies exact sequence of all
operations. Program logic determines the next instruction to execute in response to conditions and
user request.

OOPs define software as a collection of discrete oblects that specify both data structure and behavior.
OOPs Identify following aspects: Data abstraction, Inheritence, Polymorphism, Encapsulation
(information hiding)etc.

Event Driven Programming:
Events are the actions that are performed by the user during the application usage. If a user clicks a
mouse button on any object then the Click event occurs. If a user moves the mouse then the mouse
move event occurs
Any programming language, which uses these events to run a specific portion of the program, will be
called event driver programming. The GUI based programs are all developed using event driver
programming.
In the event driven model programs are no longer procedural; the do not follow a sequential logic.
The programmers do not take control and determine the sequence of execution of program. Instead,
the user can press and click on various button and boxes in a window. Each user action can cause an
event to occur, which triggers a Basic procedure (code) that you have written.

The Object model in VB 6:
In VB you will work with Objects, which have Properties and methods.
OBJECTS:
Think of an Object as a thing. Examples of Objects are Forms and Controls. Forms are the windows
and dialog boxes you place on the screen; Controls are the elements you place inside a form, such as
text coxes, command button, etc.

Properties:
Properties tell something about the Object, such as its name, color, size, etc or how it will behave. To
refer to a property of an Object, VB syntax is:
Object.Property
For example, to refer to text property of Text Box named text1, we use text1.Text

Methods:
Actions associated with the objects are called Methods. Example: Move, Print, Resize, Clear.

Ref: MSDN and Programming in VB 6 by Julia C. Bradley & Anita C. Millspaugh
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VB6 Environment / IDE (Integrated Development Environment)
The VB6 environment is where you create and test your projects. Fig 2 shows various windows in
VB6 environment. Each window can be moved, resized, opened, or closed.
Various windows in VB6 environment are:
Main VB Window
The main VB Window holds the VB Menu bar, the toolbar, and the form location and size information
FORM WINDOW
The form window is where you design the forms that makes up your user interface. When you begin
a new project, VB gives your form name the default name Form1.
The Project Explorer Window
This window holds the filenames for the files included in your project.

Fig 3: Project Explorer Window
The Properties Window
We use the properties window to set the properties for the objects in the project.
The Form Layout Window
The position of the form in this window determines the position of the form on the desktop when
execution of the project begins.
The Toolbox
Toolbox window contains a set of controls which are used to customize forms. Using this controls
user can create an interface between user and the application
Figure 4 Toolbox windows with its controls available commonly.

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Control Description
Pointer used to interact with the controls on the form
PictureBox used to display images
TextBox used to accept user input which can display only editable text
Frame used to group other controls
CommandButton used to initiate an action by pressing on the button
CheckBox used to do a choice for user (checked or unchecked)
OptionButton used in groups where one at a time can be true
ListBox used to provide a list of items
ComboBox used to provide a short list of items
HScrollBar a horizontal scrollbar
VScrollBar a vertical scrollbar
Timer used to perform tasks in specified intervals.
DriveListBox used to access to the system drives
DirListBox used to access to the directories on the system
FileListBox used to access to the files in the directory
Shape used to draw circles, rectangles, squares, ellipses
Line used to draw lines
Image used to display images. But less capability than the PictureBox
Data used to connect a database
OLE used to interact with other windows applications
Label used to display texts which cannot be edited
The Toolbar
We can use the buttons on the toolbar for frequently used operations.

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WORKING MODES IN VISUAL BASIC
VB has 3 distinct modes:
Design mode
While you are designing the user interface and writing code, you are in design mode.
Runtime mode
When you are testing and running your project, you are in runtime mode.
Break Mode
If you get a run-time error or pause project execution, you are in break time mode.

VISUAL BASIC CODE STATEMENTS
The basic program in VB requires 3 statements:
1.The Remark Statements
Remark statements are sometimes called as COMMENTS, are used for project documentation only.
They are not considered “executable” and have no effect when the project runs. The purpose of
remarks is to make the project more readable and understandable by the person who reads it.
VB remarks begin with an apostrophe.
Example:
‘this project is made in VB6
‘Exit the project
Text1.Text=”Welcome” ‘set the text property of text1 to welcome.
2. The Assignment Statements
The assignments statement assigns a value to a property or variable.
Syntax:
[Let] Object.Property = value
The LET is optional and may be included if you wish.
Example:
Text1.Text=”welcome”
Let lblName = ”ABC”
Lblname.FontSize = 12
3. The END statement
The END statement stops execution of the project. Example, Include an END statement in the sub
procedure for an EXIT button

FIRST VB PROJECT
Getting started
To open the Visual Basic environment and to work with it select and click on Microsoft Visual Basic
6.0 in the start menu. When Visual Basic is loaded the New Project dialog shown in figure 1.1 will be
displayed with the types available in Visual Basic. You can notice that Standard Exe is highlighted by
default. Standard Exe allows the user to create standard executable. Standard executable is a type
which has most of the common features of Visual basic

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Design the FORM

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Setting the Property
Object Property Value
Form1 Name Form1
Caption Form1
Command1 Name cmdOK
Caption OK
Command2 Name cmdExit
Caption Exit
Text1 Name txtName
Text
Code
Private Sub cmdExit_Click()
txtName.Text = "Welcome to VB 6"
End Sub
Private Sub cmdOK_Click()
End
End Sub
Run The Project
Press F5 or Start button on the toolbar to run the project.
Save the project

While saving the project,
The Project file is saved with extension .vbp
The form file is saved with extension .frm
The module file is saved with extension .bas
The custom controls is saved with extension .ocx

Naming Rules and Convention for Object:
Naming Rules:
When you select names for object, VB requires the name to begin with a letter.
The name can be up to 40 characters in length and can contain letter, digits and underscore.
An object name cannot include a space or punctuation marks.
The naming Convention
Always begin a name with lowercase 3 letter prefix, which identifies the object type (such as
label, command button, etc.) and capitalize the first character after the prefix( the real name
of the object).
For names with multiple words, capitalize each word in the name.
All names must be meaningful and indicate the purpose of the Object.
Example: lblMessage, cmdOk, cmdExit, lblDiscountRate, etc.

Object naming conversions of controls (prefix)
Form -frm
Label -lbl
TextBox -txt
CommandButton -cmd
CheckBox -chk
OptionButton -opt
ComboBox -cbo
ListBox -lst
Frame -fme
PictureBox -pic
Image -img
Shape -shp
Line -lin

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HScrollBar -hsb
VScrollBar -vsb

TYPES OF ERRORS
1. COMPILE ERRORS
The VB attempts to convert your program code to machine language (called compiling the
code) ,it finds any compile errors .You get the compile errors when you break the syntax rules of
Visual basics and sometimes when you use an illegal object or property.
For example, try spelling end as ennd.
txtName.Text=”ABC” is correct but txt,name=”ABC” is incorrect.
2. RUN-TIME ERRORS
If your projects halts during execution, that’s run time errors. VB displays a dialog box and goes into
break mode and highlights the statement causing the error.
Statements that cannot be executed correctly causes runtime errors. Such statements are compiled
correctly but fail too execute.
Examples: calculation with non-numeric value, divide by zero, square of negative number.
3. LOGICAL ERRORS
With logic errors, a project run but produces incorrect results. Example, result of a calculation is
incorrect or the wrong text appears or the text is OK but appears in the wrong location.

CONTEXT SENSITIVE HELP
VB 6 provides a great HELP section, if MSDN Library is installed in your machine. For Context
Sensitive Help, select a VB object, such as Text Boxes, or place the insertion point in a word in the
editor and Press F1. The MSDN Library viewer will open on the correct page, if possible, saving you a
search.

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CHAPTER 2
More Controls

In this chapter we will be discussing about various controls in VB6.

LABEL CONTROL:
A label control displays text that the user cannot directly change.
You can use labels to identify controls, such as text boxes and scroll bars that do not have their own
Caption property.
Example: lblName.Caption=”ABC”
The actual text displayed in a label is controlled by the Caption property, which can be set at design
time in the Properties window or at run time by assigning it in code.
To clear a Label’s caption:
lblMessage.Caption=””

TEXT CONTROL:
Text boxes are versatile controls that can be used to get input from the user or to display text. Text
boxes should not be used to display text that you don't want the user to change, unless you've set the
Locked property to True.
The actual text displayed in a text box is controlled by the Text property.
It can be set in three different ways:
1. at design time in the Property window,
2. at run time by setting it in code,
example: txtMessage.text=”Welcome”
3. by input from the user at run time.

The current contents of a text box can be retrieved at run time by reading the Text property.

Multiple-Line Text Boxes and Word Wrap
By default, a text box displays a single line of text and does not display scroll bars. If the text is longer
than the available space, only part of the text will be visible. The look and behavior of a text box can
be changed by setting two properties, MultiLine and ScrollBars, which are available only at design
time.
Note The ScrollBars property should not be confused with scroll bar controls, which are not
attached to text boxes and have their own set of properties.
Setting MultiLine to True enables a text box to accept or display multiple lines of text at run time.
Alignment Property of Text Box
You must set the Multiline property to true or VB ignores the alignment.

The values of alignment property, which can be set at Design time (not at run time), are:
0 – Left Justify 1 – Right Justify 2 – Center
To clear a text box at runtime:
txtMessage.Text=””

FRAMES
Frame controls are used to provide an identifiable grouping for other controls. For example, you can
use frame controls to subdivide a form functionally — to separate groups of option button controls.
In most cases, you will use the frame control passively — to group other controls — and will have no
need to respond to its events. You will, however, most likely change its Name, Caption, or Font
properties.

Adding a Frame Control to a Form
When using the frame control to group other controls, first draw the frame control, and then draw
the controls inside of it. This enables you to move the frame and the controls it contains together.

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Drawing Controls inside the Frame
To add other controls to the frame, draw them inside the frame. If you draw a control outside the
frame, or use the double-click method to add a control to a form, and then try to move it inside the
frame control, the control will be on top of the frame and you'll have to move the frame and controls
separately.
Note If you have existing controls that you want to group in a frame, you can select all the controls,
cut them to the clipboard, select the frame control, and then paste them into the frame control.

CHECK BOX
Checkboxes allow the user to select (or deselect) an option.
In any group of checkboxes, any number may be selected.
The value property of a check box is set to 0 if Unchecked (default), 1 if Checked, and 2 if Grayed
(dimmed).
Example: chkDiscount.Value=0 ‘Unchecked
chkDiscount.Value=1 ‘checked
chkDiscount.Value=2 ‘grayed
chkDiscount.Value=checked
chkDiscount.Value=unchecked

OPTION BUTTONS:
Option buttons present a set of two or more choices to the user.
Unlike check boxes, however, option buttons should always work as part of a group; selecting one
option button immediately clears all the other buttons in the group.
Defining an option button group tells the user, "Here is a set of choices from which you can choose
one and only one.”
Creating Option Button Groups
All of the option buttons placed directly on a form (that is, not in a frame or picture box) constitute
one group. If you want to create additional option button groups, you must place some of them inside
frames or picture boxes.
All the option buttons inside any given frame constitute a separate group.
Selecting or Disabling Option Buttons
An option button can be selected by:
Clicking it at run time with the mouse.
Tabbing to the option button group and then using the arrow keys to select an option button within
the group.
Assigning its Value property to True in code:
optChoice.Value = True or optChoice.Value = False

To make a button the default in an option button group, set its Value property to True at design
time. It remains selected until a user selects a different option button or code changes it.

Images Control:
The image control is used only for displaying pictures.
Pictures are loaded into the image control just as they are in the picture box: at design time, set the
Picture property to a file name and path; at run time, use the LoadPicture function.
It has a Stretch property while the picture box has an AutoSize property. Setting the AutoSize
property to True causes a picture box to resize to the dimensions of the picture; setting it to False
causes the picture to be cropped (only a portion of the picture is visible).
You can set the Visible property to TRUE to make the image invisible.
Example: imgLogo.Visible=False

SHAPE CONTROL
The shape control is used to create the following predefined shapes on forms, frames, or picture
boxes: rectangle, square, oval, circle, rounded rectangle, or rounded square.

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Predefined Shapes
The Shape property of the shape control provides you with six predefined shapes. The following
table lists all the predefined shapes, their values and equivalent Visual Basic constants:
Shape Style Constant

Rectangle 0 vbShapeRectangle

Square 1 vbShapeSquare

Oval 2 vbShapeOval

Circle 3 vbShapeCircle

Rounded Rectangle 4 vbShapeRoundedRectangle

Rounded Square 5 vbShapeRoundedSquare

LINE CONTROL
The line control is used to create simple line segments on a form, a frame, or in a picture box.
You can control the position, length, color, and style of line controls to customize the look of
applications.

CHANGING FONT PROPERTIES OF CONTROLS
At design time use the Font property to open Font dialog.
At runtime we use Font Object. A font object has several properties including Name, size, Bold, Italic,
Underline, etc.
Example:
Object.Font.Bold=True
Object.Font.Italic=True
Object.Font.UnderLine=True
Object.Font.Size=12

CHANGING COLOR PROPERTIES OF CONTROLS
At designtime we can use ForeColor property to change the color of text/caption in control.
At runtime we can use ForeColor property.
The VB6 provides 8 color constants to use:
vbBlack, vbRed, vbGreen, vbYellow, vbBlue, vbMagenta, vbCyan, vbWhite
Example:
txtName.ForeColor=vbRed
lblMessage.ForeColor=vbGreen

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CHECK BOX AND OPTION BUTTON EXAMPLE

Private Sub chkBold_Click()
Text1.Font.Bold = True
End Sub
Private Sub chkItalic_Click()
Text1.Font.Italic = True
End Sub
Private Sub chkUnderline_Click()
Text1.Font.Underline = True
End Sub
Private Sub optRed_Click()
Text1.ForeColor = vbRed
End Sub
Private Sub optGreen_Click()
Text1.ForeColor = vbGreen
End Sub
Private Sub optBlue_Click()
Text1.ForeColor = vbBlue
End Sub

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SHAPE CONTROL EXAMPLE

Private Sub cmdRectangle_Click()
Shape1.Shape = 0
End Sub
Private Sub cmdSquare_Click()
Shape1.Shape = 1
End Sub
Private Sub Oval_Click()
Shape1.Shape = 2
End Sub
Private Sub cmdCircle_Click()
Shape1.Shape = 3
End Sub
Private Sub cmdRoundedRectangle_Click()
Shape1.Shape = 4
End Sub
Private Sub cmdRoundedSquare_Click()
Shape1.Shape = 5
End Sub

DEFINING KEYBOARD ACCESS KEYS
Many people prefer to use the keyboard, rather than a mouse, for most operations.
You can make your program respond to keyboard by defining access keys.
For example: In the below diagram, you can select the OK button by pressing alt+o and the
exit button by pressing alt+e.

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We can set access keys for command button, option buttons and check boxes. When you define their
Caption property. Type an ampersand (&) in front of the character you want for the access key; VB
underlines the character.
For example:
&OK for OK
E&xit for Exit

Specifying the Default and Cancel Properties
On each form, you can select a command button to be the default command button — that is,
whenever the user presses the ENTER key the command button is clicked regardless of which other
control on the form has the focus. To specify a command button as default set the Default property to
True.
You can also specify a cancel button. When the Cancel property of a command button is set to True,
it will be clicked whenever the user presses the ESC key, regardless of which other control on the
form has the focus.

Setting the Tab Order
The tab order is the order in which a user moves from one control to another by pressing the TAB
key. Each form has its own tab order. Usually, the tab order is the same as the order in which you
created the controls.
For example, assume you create two text boxes, Text1 and Text2, and then a command button,
Command1. When the application starts, Text1 has the focus. Pressing TAB moves the focus between
controls in the order they were created
To change the tab order for a control, set the TabIndex property. The TabIndex property of a
control determines where it is positioned in the tab order. By default, the first control drawn has a
TabIndex value of 0, the second has a TabIndex of 1, and so on. When you change a control's tab
order position, Visual Basic automatically renumbers the tab order positions of the other controls to
reflect insertions and deletions. For example, if you make Command1 first in the tab order, the
TabIndex values for the other controls are automatically adjusted upward, as shown in the following
table.
TabIndex before it is changed TabIndex after it is changed
Control

Text1 0 1

Text2 1 2

Command1 2 0

The highest TabIndex setting is always one less than the number of controls in the tab order
(because numbering starts at 0). Even if you set the TabIndex property to a number higher than the
number of controls, Visual Basic converts the value back to the number of controls minus 1.
Note Controls that cannot get the focus, as well as disabled and invisible controls, don't have a
TabIndex property and are not included in the tab order. As a user presses the TAB key, these
controls are skipped.
Removing a Control from the Tab Order
Usually, pressing TAB at run time selects each control in the tab order. You can remove a control
from the tab order by setting its TabStop property to False (0).
A control whose TabStop property has been set to False still maintains its position in the actual tab
order, even though the control is skipped when you cycle through the controls with the TAB key.

CREATING TOOLTIPS
The word or short phrase that describes the function of a toolbar button or other tool. The ToolTip
appears when you pause the mouse pointer over an object.

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ToolTipText Property
Returns or sets a ToolTip.
At design time you can set the ToolTipText property string in the control's properties dialog box.

At Run-time:
object.ToolTipText [= string]
The ToolTipText property syntax has these parts:
Part Description

object An object expression that evaluates to an object in the Applies To list.

string A string associated with an object in the Applies To list. that appears
in a small rectangle below the object when the user's cursor hovers
over the object at run time for about one second.

With Statement
Executes a series of statements on a single object or a user-defined type.
Syntax
With object
[statements]
End With
The With statement syntax has these parts:
Part Description

object Required. Name of an object or a user-defined type.

statements Optional. One or more statements to be executed on object.

Remarks
The With statement allows you to perform a series of statements on a specified object without
requalifying the name of the object. For example, to change a number of different properties on a
single object, place the property assignment statements within the With control structure, referring
to the object once instead of referring to it with each property assignment. The following example
illustrates use of the With statement to assign values to several properties of the same object.
With MyLabel
.Height = 2000
.Width = 2000
.Caption = "This is MyLabel"
End With
Note Once a With block is entered, object can't be changed. As a result, you can't use a single With
statement to affect a number of different objects.

Concatenating Strings:
Used to force string concatenation of two expressions.
Syntax

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result = expression1 & expression2
The & operator syntax has these parts:
Part Description

result Required; any String or Variant variable.

expression1 Required; any expression.

expression2 Required; any expression.

Example:
txtOutPut.Text= “Welcome ” & “ To VB 6”
txtName.Text= txtFirstName.Text & “ ” & txtLastName.Text

Remarks
If an expression is not a string, it is converted to a String variant. The data type of result is String if
both expressions are string expressions; otherwise, result is a String variant. If both expressions are
Null, result is Null. However, if only one expression is Null, that expression is treated as a zero-length
string ("") when concatenated with the other expression. Any expression that is Empty is also treated
as a zero-length string.

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CHAPTER 3
Variables, Constants and Calculations

Variables and Constants
Memory locations that hold data that can be changed during project execution are called Variables.
Memory locations that hold data that cannot be changed during project execution are called
Variables.
For example,
Variable: a customer’s name will vary as the information for each individual is being processed.
Constant: However the name of the company and the sales tax rate will remain the same.

Identifier:
When you declare a variable or named constant, VB reserves an area of memory and assigns it a
name, called an Identifier.

Data types in visual basic 6.0
The data type of a variable or constant indicates what type of information will be stored in the
allocated memory space.
The default data type is Variant.
If you do not specify a data type, your variables and constant will be Variants.
Advantages & Disadvantages of using Variant data type:
Advantages Disadvantages
1.It’s easy 1. Less efficient than other data types, i.e., they
2. variables and constants change their require more memory space and operate less
appearance as needed for each situation. quickly than other data types.

The best practice is always specify the data types.
Other data types are:

1. Numeric
Byte Store integer values in the range of 0 - 255
Integer Store integer values in the range of (-32,768) - (+ 32,767)
Long Store integer values in the range of (- 2,147,483,468) - (+ 2,147,483,468)
Single Store floating point value in the range of (-3.4x10-38) - (+ 3.4x1038)
Double Store large floating value which exceeding the single data type value
store monetary values. It supports 4 digits to the right of decimal point and
Currency
15 digits to the left
2. String
Use to store alphanumeric values. A variable length string can store approximately 4 billion
characters
3. Date
Use to store date and time values. A variable declared as date type can store both date and time
values and it can store date values 01/01/0100 up to 12/31/9999
4. Boolean
Boolean data types hold either a true or false value. These are not stored as numeric values and
cannot be used as such. Values are internally stored as -1 (True) and 0 (False) and any non-zero
value is considered as true.

Naming rules and convention in VB 6.0
These are the rules to follow when naming elements in VB - variables, constants, controls,
procedures, and so on:

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* A name must begin with a letter.
* May be as much as 255 characters long
* Must not contain a space or an embedded period or type-declaration characters used to
ype; these are ! # % $ & @
* Must not be a reserved word (that is part of the code, like Option, for example)
* The dash, although legal, should be avoided because it may be confused with the minus
sign. Instead of First-name use First_name or FirstName.
* use a three letter prefix to append the name while declaring it.
Examples: data type and their prefixes:
bln Boolean
cur Currency
dbl Double-precision floating point
dtm Date/ time
int Integer
lng Long Integer
sng Single
str String
vnt Variant

Variables:
Variables are the memory locations which are used to store values temporarily. A defined naming
strategy has to be followed while naming a variable. A variable name must begin with an alphabet
letter and should not exceed 255 characters. It must be unique within the same scope. It should not
contain any special character like %, &, !, #, @ or $.
Declaring variables
To declare a variable, we use DIM statement.
DIM statement General Form:
Dim identifier [as DataType]
If you omit the optional data type, the variable’s type defaults to variant.
Example:
Dim vntChanging
Dim strName as String
Dim intTotal as Integer
The reserved word Dim is really short for Dimension, which means “size”. When you declare a
variable, the amount of memory reserved depends on its data types.

Data Type Numer of Bytes of Memory Allocated
Boolean 2
Byte 1
Currency 8
Date 8
Double 8
Integer 2
Long 4
Single 4
String (Variable Length) 10 bytes plus 1 byte for each character in the
string
Variant Holding Numbers – 16 bytes
Holding Characters – 22 bytes plus 1 byte for
each character in the string

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SCOPE OF VARIABLES
The visibility of a variable is referred to as its Scope. Visibility means “this variable can be seen or
used in this location”
The scope is said to be global, module level or local.
Global variable
A global variable may be used in all procedures of a project. To indicate a global level
variable, place a prefix of g before the identifier.
Example: gintTotalSum
Module level variable
Module level variables are accessible from all the procedure of a form. To indicate a module
level variable, place a prefix of m before the identifier.
We place the module level variables and constants in the General Decalaration section of the form.
Example:
______________________________
Option Explicit
Dim mintTotal as Integer
______________________________
Private sub cmdSum_click()
mintTotal=text1.text + text2.text
End sub
_______________________________
Private sub cmdTotal_click()
mintTotal= mintTotal * 0.10
End sub
________________________________
Local variable
A local variable may be used only within the procedure in which it is defined. Any variable
that you declare inside a procedure is local in scope; it is known to that procedure.
Example:
Private sub cmdSum_click()
Dim intNum as Integer
Dim curPrice as Integer
Dim blnCounter as Boolean
End sub

Constant – Named and Intrinsic
Constant provide a way to use words to describe a value that doesn’t change.
Constant can be Named or Intrinsic.
1. Named Constant:
The constant that you define for yourself are called Named Constants. We give the constant a name, a
data type and a value. Once a value is decaled as a constant, its value cannot be changed during
program execution.
The data type and the data type of the value must match for a constant.
We declare named constant using the keyword Const.
General Form:
Const Identifier [ As DataType ] = Value
Example:
Const strAddress As String = “ Malad ”
Const curSalesTaxRate as Currency = 0.08
Assigning Values to Constant
String Literals
String constants are called String literals and may contain letters, digits and special characters, such
as $#@%&*.
Also, to declare a constant such as

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He said, “I liked it” , it are declared as
Const strName as String=””He said, “I liked it”””

Numeric Constants
Numeric constants may contain only the digits (0-9), a decimal
Point and a sign(+ or -) at the left side. We cannot include a comma, dollar sign, any other special
character, or a sign at the right side.
Data Type Constant value Example
Integer 125
2170
Single or Currency 101.25
-5.2
String literals “VB”
“103”
“She said ““Hello.”””

2. Intrinsic Constant
Intrinsic constant are system-defined constants. Several sets of Intrinsic constants are stored in
library files and available for use in VB programs.
Intrinsic constants use a 2-charater prefix to indicate the source, such as
Vb for Visual basic, db for Access Objects and xl for Excel.
Example: vbRed, vbGreen, etc.

Operators in Visual Basic

Arithmetical Operators

Operators Description Example Result

+ Add 5+5 10

- Substract 10-5 5

/ Divide 25/5 5

Integer Division 203 6

* Multiply 5*4 20

^ Exponent (power of) 3^3 27

Mod Remainder of division 20 Mod 6 2

& String concatenation "George"&" "&"Bush" "George Bush"
Relational Operators
Operators Description Example Result

> Greater than 10>8 True

< Less than 10>8 False

>= Greater than or equal to 20>=10 True

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<= Less than or equal to 10<=20 True

<> Not Equal to 5<>4 True

= Equal to 5=7 False

Logical Operators
Operators Description

OR Operation will be true if either of the operands is true

AND Operation will be true only if both the operands are true

Val Function

A function performs an action and returns a Value.
The Expression to operate upon, called the arguments, must be enclosed in parenthesis.

The Val function converts text data into a numeric value.
General form:
Val(ExpressionToConvert)
The expression can be the property of a control, a variable or a constant.

A function cannot stand by itself. It returns a value that can be part of a statement, such as the
assignment statements.
Example:
intQuantity=Val(txtQuantity.Text)
curPrice=Val(txtPrice.Text)

Important: When the Val function converts an argument to numeric, it begins at the argument’s left
most character. If that character is a numeric digit, decimal point, or sign, It converts the character to
numeric and moves to the next character. As soon as a nonnumeric character is found, the operation
stops. Example:

Argument Numeric Value Returned by the Val Function
(blank) 0
123.45 123.45
$100 0
1,000 1
A123 0
123A 123
4C5 4
-123 -123
+123 123
12.45.2 12.45

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CALCULATOR PROGRAM

Code:
Private Sub cmdAdd_Click()
txtOutput.Text = Val(txtNum1.Text) + Val(txtNum2.Text)
End Sub

Private Sub cmdDifference_Click()
txtOutput.Text = Val(txtNum1.Text) - Val(txtNum2.Text)
End Sub

Private Sub cmdMultiply_Click()
txtOutput.Text = Val(txtNum1.Text) * Val(txtNum2.Text)
End Sub

Private Sub Command4_Click()
txtOutput.Text = Val(txtNum1.Text) / Val(txtNum2.Text)
End Sub

FORMATTING DATA
Use the formatting functions to format the data.
To format means to control the way the output look.
For example, 12 is just a number but $12.00 conveys more meaning for dollar amount.

VB 6 introduces 4 new formatting functions –
1. FormatCurrency
FormatCurrency Returns an expression formatted as a number with a leading currency
symbol ($)
Simple Form
FormatCurrency (Expression)
General Form
FormatCurrency (Expression[,NumDigitsAfterDecimal [,IncludeLeadingDigit
[,UseParensForNegativeNumbers [,GroupDigits]]]])

2. FormatNumber
FormatNumber Returns an expression formatted as a number

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Simple Form
FormatNumber(Expression)
General Form
FormatNumber(Expression[,NumDigitsAfterDecimal [,IncludeLeadingDigit

3. FormatPercent
FormatPercent Returns an expression formatted as a percentage (multiplied by 100) with a
trailing % character.
Simple Form
FormatPercent (Expression)
General Form
FormatPercent (Expression[,NumDigitsAfterDecimal [,IncludeLeadingDigit

For the examples below, assume dblTestNumber contains the value 12345.678

Expression Result
FormatNumber(dblTestNumber, 2, True, True, True) 12,345.68
FormatCurrency(dblTestNumber, 2, True, True, True) $12,345.68
FormatPrecent(dblTestNumber, 2, True, True, True) 1,234,567.80%

"Try It" Code:

Private Sub cmdTryIt_Click()

Dim dblTestNumber As Double

dblTestNumber = Val(InputBox("Please enter a number:"))

Print "Input: "; Tab(25); dblTestNumber
Print "Using FormatNumber:"; Tab(25); FormatNumber(dblTestNumber, 2, True, True,
True)
Print "Using FormatCurrency:"; Tab(25); FormatCurrency(dblTestNumber, 2, True, True,
True)
Print "Using FormatPercent:"; Tab(25); FormatPercent(dblTestNumber, 2, True, True, True)
End Sub

Output:

- 22 -


4. FormatDateTime
FormatDateTime Returns an expression formatted as a date or time.

Syntax:

FormatDateTime(Date[,NamedFormat])

The FormatDateTime function syntax has these parts:

Part Description
Date Required. Date expression to be formatted.
NamedFormat Optional. Numeric value that indicates the date/time format used. If omitted,
vbGeneralDate is used.

Settings:
The NamedFormat argument has the following settings:
Constant Value Description
vbGeneralDate 0 Display a date and/or time. If there is a date part, display it as a short
date. If there is a time part, display it as a long time. If present, both
parts are displayed.

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vbLongDate 1 Display a date using the long date format specified in your computer's
regional settings.
vbShortDate 2 Display a date using the short date format specified in your computer's
regional settings.
vbLongTime 3 Display a time using the time format specified in your computer's
regional settings.
vbShortTime 4 Display a time using the 24-hour format (hh:mm).

"Try It" Code:

Private Sub cmdTryIt_Click()

Print "Using vbGeneralDate:"; Tab(25); FormatDateTime(Now, vbGeneralDate)
Print "Using vbLongDate:"; Tab(25); FormatDateTime(Now, vbLongDate)
Print "Using vbShortDate:"; Tab(25); FormatDateTime(Now, vbShortDate)
Print "Using vbLongTime:"; Tab(25); FormatDateTime(Now, vbLongTime)
Print "Using vbShortTime:"; Tab(25); FormatDateTime(Now, vbShortTime)
End Sub

Output:

- 24 -


- 25 -

Vb 6ch123

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