1. VISUAL BASIC 6.0
Designed by Mrinal Kanti Nath

2. INTRODUCTION
Visual Basic is an object-oriented programming development system for creating applications that run under any of the Microsoft Windows environments. It has the following two major components:
1. An extensive collection of prewritten tools, called controls.
2. A complete set of program commands, derived from Microsoft’s implementation of the classical Basic programming language.
Designed by Mrinal Kanti Nath

3. EVENT DRIVEN PARADIGM
Each feature included within the program is activated only when the user responds to a corresponding object within the user interface.
The program’s response to an action taken by the user is referred to as an event.
The group of Basic commands that brings about this response is called an event procedure.
Designed by Mrinal Kanti Nath

4. OBJECT RELATED CONCEPTS
FORMS: In VB, a window is called a form. Each form includes a title bar at the top & it also include a menu bar, a status bar, one or more toolbars, slide bars, etc.
CONTROLS: The icons with which the user interacts are called controls. Commonly used controls include command buttons, option buttons, check boxes, labels, text boxes, picture boxes and menus.
OBJECTS: Forms and controls are referred to collectively as objects.
Designed by Mrinal Kanti Nath

5. OBJECT RELATED CONCEPTS CONTD..
PROPERTIES: Objects include properties that generally define their appearance or behavior. For example, the name, caption, height, width, background color, location etc..
METHODS: Some objects also include special program statements called methods. For example, show is a method that can be used with a hidden form to make it visible.
Designed by Mrinal Kanti Nath

6. VB PROGRAM COMPONENTS In VB, a program is referred to as a project.
Every VB project consists of at least two separate files – a project file (.vbp) and a form file (.frm)
Some projects include multiple form files and other types of files, such as class module (.cls) files, standard module (bas) files, resource (.res) files, and ActiveX control (.ocx) files.
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10. Code Editor Window
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11. Example: Area of a Circle
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12. Example: Area of a Circle Contd..
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13. Example: Area of a Circle Contd..
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14. Example: Area of a Circle Contd..
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15. Example: Area of a Circle Contd..
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16. Example: Area of a Circle Contd..
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17. Example: Area of a Circle Contd..
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18. Example: Area of a Circle Contd..
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19. Data Types and Data Declaration
Integer
Long (Long Integer)
Single
Double
String
E.G.-
Dim variable name As data type
Dim Area As Single
Dim StudentName As String
Designed by Mrinal Kanti Nath

20. Const TaxRate As Single = 0.28
Named Constant
Similar to variables. But, variables can be reassigned different values within a program, whereas named constants remain unchanged throughout a program.
E.g.-
Const TaxRate As Single = 0.28
Designed by Mrinal Kanti Nath

21. User Defined Data Types
Type Customer
CustomerName As String
AcctNo As Integer
Balance As Single
End Type
Once the data type has been defined, we can declare one or more variables of this data type, as follows.
Dim OldCustomer As Customer, NewCustomer As Customer
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22. Arithmetic Operators The standard arithmetic operators are
Addition: + (plus sign)
Subtraction: − (minus sign)
Multiplication: * (asterisk)
Division: / (slash)
Exponentiation: ^ (caret, or upward-pointing arrow)
Integer division: \ (backward slash)
Integer remainder: Mod
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23. Relational Operators Equal: = Not equal: <> Less than: <
Less than or equal to: <=
Greater than: >
Greater than or equal to: >=
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24. Logical Operators
And will result in a condition that is true if both expressions are true.
Or will result in a condition that is true if either expression is true, or if they are both true
Xor will result in a condition that is true only if one of the expressions is true and the other is false.
Not is used to reverse (negate) the value of a logical expression.
Eqv will result in a condition that is true if both expressions have the same logical value
Imp will always result in a true condition unless the first expression is true and the second is false.
Designed by Mrinal Kanti Nath

25. Hierarchy Of Operations
Exponentiation ^
Negation (i.e., preceding a numeric −quantity with a minus sign)
Multiplication and division * /
Integer division \
Integer remainder Mod
Addition and subtraction + −
Relationals = <> < <= > >=
Logical Not Not
Logical And And
Logical Or Or
Logical Xor Xor
Logical Eqv Eqv
Logical Imp Imp
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26. Inserting Parentheses
[ 2(a + b)2 + (3c)2 ] m / (n+1)
A Visual Basic expression corresponding to this algebraic term is
(2 * (a + b) ^ 2 + (3 * c) ^ 2) ^ (m / (n + 1))
((2 * ((a + b) ^ 2)) + ((3 * c) ^ 2)) ^ (m / (n + 1))
Both are correct.
The arithmetic expression −x ^ n
is equivalent to −(x ^ n) or −1 * (x ^ n)
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27. String Concatenation Str1 = "TEN" Str2 = "THOUSAND”
Str1 & " " & str2 & " DOLLARS”
Str1 + " " + str2 + " DOLLARS”
Both will print:
TEN THOUSAND DOLLARS
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29. Print Statement
Print statement is used to display information within the currently active form, beginning in the upper left corner.
Dim Student As String, X As Integer, C1 As Single, C2 As Single
Student = "Aaron"
X = 39
C1 = 7
C2 = 11
Print "Name:", Student, X, (C1 + C2) / 2
Designed by Mrinal Kanti Nath

30. If-Then Syntax: If logical expression Then executable statement End If
Example:
If income <= Then
tax = 0.2 * pay
net = pay - tax
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31. If-Then-Else Syatax: If logical expression Then executable statements
End If
Example:
If (status = "single") Then
tax = 0.2 * pay
tax = 0.14 * pay
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32. If-Then-Else
If logical expression 1 Then executable statements ElseIf logical expression 2 Then repeated ElseIf clauses Else End If
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33. Case structure Syntax
Select Case expression Case value1 executable statements Case value Case Else End Select
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34. Case Structure Example
Dim x, z, n As Integer Select Case n Case 1 z = x Case 2 z = x ^ 2 Case 3 z = x ^ 3 Case Else MsgBox("ERROR - Please try again") End Select
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35. For- Next Syntax For index = value1 To value2 executable statements
Next index
Example:
sum = 0
For i = 1 To 10
sum = sum + i
Next i
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36. For- Next Contd..
For index = value1 To value2 Step value3 executable statements Next index sum = 0 For count = 2.5 To -1 Step -0.5 sum = sum + count Next count count will take on the values 2.5, 2.0, 1.5, . . ., 0.0, -0.5, Hence, the final value of sum will be 6.0 (because – 0.5 – 1.0 = 6.0).
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37. Do Loop First form: Do While logical expression executable statements
Second form:
Do Until logical expression
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38. Do Loop Contd.. Third form: Do executable statements
Loop While logical expression
Fourth form:
Loop Until logical expression
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39. Do Loop Contd..
First form continues to loop as long as the logical expression is true
Second form continues to loop as long as the logical expression is not true (until the logical expression becomes true).
Third form continues to loop as long as the logical expression is true.
Fourth form continues to loop as long as the logical expression is not true.
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40. While-Wend While logical expression executable statements Wend
Example:
sum = 0
count = 1
While count <= 10
sum = sum + count
count = count + 1
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41. Stop Statement
Used to terminate the execution at any point in the program.
The statement consists simply of the keyword Stop
May appear anywhere in a Visual Basic program except at the very end. Multiple Stop statements may appear in the same program, as dictated by the program logic.
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44. Thank You
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