The Initial Visual Basic Screen Toolbox Project Explorer window
Properties window Form Menu bar Description pane Form Layout window
Toolbar Project Container window
Slide 4
Steps to Create a Visual Basic Program 1. Create the interface
by placing controls on the form 2. Set properties for the controls
and the form 3. Write code for event procedures associated with the
controls and the form
Slide 5
Four Useful Visual Basic Controls Text Boxes Labels Command
Buttons Picture Boxes
Slide 6
Placing a Text Box on a Form Double-click on the text box icon
in the toolbox to add a text box to your form Activate the
properties window (Press F4) Set values of properties for text
box
Slide 7
Placing a Text Box on a Form Text box
Slide 8
Some Useful Properties of Objects Name Caption Text (for Text
Boxes) BorderStyle Visible BackColor Alignment Font Border Style:
Setting the BorderStyle to 0-None removes the border from an object
Visible: Setting the property to false hides an object when the
program run. The object can be set to reappear with code BackColor:
Specifies the background color for text box, label, picture box or
form.. Also specific background color for a command button having
Style set to 1-Graphical BackStyle: The background of a label is
opaque by default. Setting the background style of a label to
transparent causes whatever is behind the label remain visible.;
the background color of the label essentially becomes see through
Font: Two unusual fonts are Symbols and Wingdings> For instance
with the windingsfonts, changing the text to % & and J yields a
bell, a book, a candle and a smiling face
Slide 9
Example
Slide 10
Naming Objects: Use the Property window to change the Name
property of an object Good programming practice dictates that each
object name begins with a three letter prefix that identifies the
type of object.
Slide 11
Naming Objects:
Slide 12
Naming Objects An Object Name Must Start with a letter Can
include numbers and underscore (_) Cannot include punctuation or
spaces Can be a maximum of 40 characters
Slide 13
Visual Basic Events Code is a set of statements that instruct
the computer to carry out a task. Code can be associated with
events When an event occurs, the code associated with that event
(called an Event Procedure) is executed.
Slide 14
Creating An Event Procedure Double-click on an object to open a
Code window. (The empty default event procedure will appear. Click
on the Procedure box if you want to display a different event
procedure.) Write the code for that event procedure.
Slide 15
Example of An Event Procedure Private Sub objectName_event ( )
Here are your statements End Sub Private Sub txtOne_GotFocus( )
txtOne.Font.Size = 12 txtOne.Font.Bold = False End Sub
Slide 16
More Examples Private Sub cmdButton_Click( ) txtBox.ForeColor =
vbRed txtBox.Font.Size = 24 txtBox.Text = Hello End Sub
Slide 17
Exercises 11. Private Sub cmdButton_Click( ) txtOne.text =
Hello Doctor End Sub 12. Private Sub cmdButton_Click( )
txtOne.ForeColor = red End Sub
Slide 18
Exercises 13. Private Sub cmdButton_Click( ) txtBox.Caption =
Hello End Sub 16. Private Sub cmdButton_Click( ) txtOne.MultiLine=
True End Sub
Slide 19
Tips Most Properties can be set or altered at run time with
code. cmdButton.visible = False The BorderStyle and MultiLine
properties of a text box can only be set from the properties window
surrounds Caption, Name, Font.Name or strings not True, vars or
numeric constants
Slide 20
Color Constants At design time colors are selected from a
palette At run time the eight most common colors can be assigned
with the color constants: vbBlackvbMagenta vbRedvbCyan
vbGreenvbYellow vbBluevbWhite
Slide 21
Components of Visual Basic Statements Constants Variables
Keywords (reserved words)
Slide 22
Constant Can NOT change during the execution of a program.
Types of Constants: numeric constants string constants
Slide 23
Valid Numeric Constants: Integer Real number -2987 -1900.05 16
0.0185 5 10.56
String Constants: A sequence of characters treated as a single
item The characters in a string must be surrounded by double quotes
( )
Slide 26
Valid String Constants A rose by any other name 9W 134.23 She
said, stop, thief!
Slide 27
Invalid String Constants Down by the Seashore 134.24 She said,
Stop, thief!
Slide 28
Arithmetic Operations Operator Operation Basic expression ^
Exponentiation A ^ B * Multiplication A * B / Division A / B +
Addition A + B - Subtraction A - B
Slide 29
Variables A storage location in main memory whose value can be
changed during program execution. These storage locations can be
referred to by their names. Every variable has three properties: a
Name, a Value, and a Data Type. Types of variables: Numeric and
String
Slide 30
Rules for Naming Variables Must begin with a letter Must
contain only letters, numeric digits, and underscores ( _ ) Can
have up to 255 characters Cannot be a Visual Basic language keyword
(for example, Sub, End, False) VB does not distinguish between
uppercase and lowercase letters. Example: numberOfCars,
tax_Rate_1994 Let statement assigns values to variables and Print
method displays the values of variable.
Slide 31
Numeric Variables Used to store numbers Value is assigned by a
statement of the form: numVar = expression The variable must be on
the left and the expression on the right.
String Variables A string variable stores a string. The rules
for naming string variables are identical to those for naming
numeric variables. When a string variable is first declared, its
value is the empty string.
Slide 35
String Variable Example Private Sub cmdShow_Click()
picOutput.Cls phrase = "win or lose that counts." picOutput.Print
"It's not whether you "; phrase picOutput.Print "It's whether I ";
phrase End Sub
Slide 36
Concatenation Two strings can be combined by using the
concatenation operation. The concatenation operator is the
ampersand (&) sign.
Slide 37
Examples of Concatenation: strVar1 = Hello strVar2 = World
picOutput.Print strVar1& strVar2 txtBox.Text = 32 &
Chr(176) & Fahrenheit
Slide 38
Assignment Statement: The statement var = expr assigns the
value of the expression to the variable tax = 0.02 * (income - 500
* dependents) sum = 2 + x + 4.6 + y
Slide 39
Valid Assignment Statements count = count + 1 num = 5 count =
count + num /2
Keywords Words that have predefined meaning to Visual Basic.
Can Not be used as variable names. Examples: End- Print Sub- Let If
-Select While-Call The VB editor automatically capitalizes the
first letter of reserved word
Slide 42
Visual Basic Print Statement Print is a method used to display
data on the screen or printer. Can be used to display values of
variables or expressions Private Sub cmdCompute_Click()
picResults.Print 3 + 2 picResults.Print 3 - 2 picResults.Print 3 *
2 picResults.Print 3 / 2 picResults.Print 3 ^ 2 picResults.Print 2
* (3 + 4) End Sub
Slide 43
Examples of Print Statements x = 15 y = 5 picOutput.Print (x +
y) / 2, x / y Output: 103
Slide 44
Declaring Variable Types Use the Dim statement to declare the
type of a variable. Examples: Dim number As Integer Dim flower As
String Dim interestRate As Single From now on we will declare all
variables. Declaring variables is regarded as good programming
practice.
Slide 45
Data Types : Single: a numeric variable that stores real
numbers Integer: a numeric variable that stores integer numbers
(from -32768 to 32767) String: a variable that stores a sequence of
characters
Slide 46
Using Text Boxes for Input/Output The contents of a text box
are always a string. Numbers can be stored in text boxes as
strings.
Slide 47
Using Text Boxes for Input/Output The contents of a text box
should be converted to a number before being assigned to a numeric
variable. Val(txtBox.Text) gives the value of a numeric string as a
number Example: Dim numVar as Single numVar = Val(txtBox.Text)
Slide 48
Example (convert miles to furlongs and vice versa) Example 1
xString=528 xValue=Val(xString) xValue=528 Example 2 yValue=428
yString=Str(yValue) yString=428
Slide 49
Example (convert miles to furlongs and vice versa) Private Sub
txtFurlong_LostFocus() txtMile.Text = Str(Val(txtFurlong.Text / 8))
End Sub Private Sub txtMile_LostFocus() txtFurlong.Text = Str(8 *
Val(txtMile.Text)) End Sub
Slide 50
Program Documentation An apostrophe ( ' ) is used to indicate
that the remainder of the line is a comment. (Comments are ignored
by Visual Basic.) Remarks can appear on a separate line or
following a Visual Basic statement.
Slide 51
Using Message Dialog Box for Output The message dialog box is
used to present a pop-up window containing information for the user
Syntax: MsgBox prompt,, title
Slide 52
Example of a Message Dialog Box MsgBox Nice try, but no cigar,,
Consolation Stays on the screen until the user presses OK
Slide 53
Formatting the Output: Create easily readable output In the
Print method, the spacing of the output is controlled by the
following devices: semicolon comma Tab function
Slide 54
Semicolons The next value output is placed in the next column
position. Example: picOutput.Print Patrick; Jon Output:
PatrickJon
Slide 55
Example of Semicolon Chapter 3 - Visual Basic Schneider
picOutput.Print 100; -200; 300 Output Screen: 100 -200 300 One
space Two spaces
Slide 56
Commas Chapter 3 - Visual Basic Schneider A comma in a Print
method causes the next value output to be placed in the next
available print zone. Each print zone is 14 positions wide.
Slide 57
Using Commas Example: picOutput.Print SEE, YOU, SOON Output
Screen: SEE YOU SOON Column 1 Column 15 Column 29
Using Commas A print zone can be skipped by typing consecutive
commas Example: picOutput.Print HOURLY,, PAY Output Screen: HOURLY
PAY Column 29
Slide 60
Tab Function Specifies the column where output will start Use
only semicolons with the Tab function Can only be used to advance
the print position (cannot move backwards)
Slide 61
Example of Tab Function Example: picOutput.Print Tab(3); Hi
there! ; Tab(25) ;Bye! Output Screen: Hi there! Bye! Column 3
Column 25
Slide 62
Built-In Functions Take one or more input values and return an
output value A means provided by Visual Basic for carrying out
small, common tasks Types of Built-In functions Numeric functions
(manipulate numbers) String functions (manipulate strings)
Slide 63
Numeric Functions
Slide 64
Example of Numeric Functions Private Sub cmdEvaluate_Click()
Dim n As Single, root As Single n = 6.76 root = Sqr(n)
picResults.Print root; Int(n); Round(n,1) End Sub Output: 2.6 6
6.8
Slide 65
Commonly-Used String Functions Function: Left(Penguin, 4)
Purpose: Returns the number of characters specified, starting at
the beginning of the string
Slide 66
Commonly-Used String Functions Function: Right(Gotham City, 4)
Purpose: Returns the number of characters specified from the end of
the string
Slide 67
Commonly-Used String Functions Function: Mid(Commissioner, 4,
3) Purpose: Returns the substring starting at the position
indicated by the first number and continuing for the length
specified by the second number
Slide 68
Commonly-Used String Functions Function: UCase(Yes) Purpose:
Converts any lowercase letters in a string to uppercase
Slide 69
String-Related Numeric Functions Function: InStr(John Smith, m)
Purpose: Searches for the first occurrence of one string in another
and gives the position at which the string is found
Slide 70
String-Related Numeric Function Function: Len(John Smith)
Purpose: Returns the number of characters in the string.
Slide 71
Strings and string Functions examples picBoard.print
len(left(welcome,3)) picBoard.print UCase(left(welcome,3))
Slide 72
Format Functions The format functions provide detailed control
of how numbers, dates, and strings are displayed. Examples
FormatNumber (12345.678, 1) 12,345.7 FormatCurrency (12345.678, 2)
$12,345.68 FormatPercent (.185, 2) 18.50% FormatNumber (1 + Sqr(2),
3) 2.414
Slide 73
Format Function Format (expr, @..@) Purpose: The value of this
function is the value of expr right justified in a field of n
spaces, where n is the number of @ symbols.
Rnd Function Chapter 3 - Visual Basic Schneider Returns a
random number from 0 to 1. (excluding 1). Example: picBox.Print Rnd
Output: Displays a random number from 0 to 1 (0 included and 1
excluded). Example: picBox.Print Rnd +5 Output: Displays a random
number from 5 to 6 (5 included and 6 excluded).