1. Introduction to Programming Lecture 2
Msury Mahunnah,
Department of Informatics,
Tallinn University of Technology

2. Microsoft Visual Studio and Visual Basic
The Visual Studio is an integrated development environment (IDE) for building, testing, debugging, and deploying a variety of applications:
Windows applications,
web applications,
classes and
custom controls, and
even console applications.
Visual Studio supports different programming languages: Microsoft Visual Basic, Visual J#, Visual C#, and Visual C++.

3. Getting Started Launch Microsoft Visual Basic
From the File menu, select New Project
The type of project, select Windows Forms Application
Define Windows application name, OK
Add control(s) from “Common Controls”
To execute select from menu:
“Debug-> Start Debugging” or press F5

4. Toolbox Includes different Windows form items
Mainly we are using components (objects) from
Common Controls (Button, CheckBox, ...)
Containers (GroupBox, Panel)
Components (Timer)
Every Windows form components (objects) has its own:
Properties (= attributes, describing a object)
Methods (= acts)
Events (implemented by procedures)

5. Using object properties and methods
object_name.property object_name.method The examples Button1.Hide() Button1 – object name Hide() – a method Button1.Width = 50 Width – property

6. The variable
A variable is a named location in computer memory that maintains values.
A variable is a memory field or a cell to keep the values, provided with a name.

7. The types of variables
VB recognizes the following five categories of variable:
Numeric (stores numbers)
String (stores text)
Boolean (strores values “TRUE” and “FALSE”)
Date (stores timevalues and datevalues)
Object (can stores any type of data)

8. Numeric variables Integer (there are several Integer data types)
Decimal
Single (floating-point numbers with limited precision)
Double (floating-point numbers with extreme precision)

9. Memory representation
VB numeric data types
Data type
Memory representation
Stores in the range ...
Byte (Byte)
1 byte
0 to 255 (int)
Signed Byte (SByte)
-128 to 127 (int)
Short (Int16)
2 bytes
-32,768 to 32,767 (int)
Integer (Int32)
4 bytes
-2,147,483,648 to 2,147,483,647 (int)
Long (Int64)
8 bytes
-9x10^18 to 9x10^18 (int)
Unsigned Short (UShort)
0 to 65,536
Unsigned Integer (UInteger)
0 to 4,294,967,295
Unsigned Long(ULong)
0 to 18,446,744,073,709,551, 615
Single Precision (Single)
-3.40E38 to -1.40E-45 (neg numbers)
1.40E-45 to 3.40E38 (pos numbers)
Double Precision (Double)
-1.79E308 to -4,94E-324 (neg numbers)
4.94E-324 to 1.79E308 (pos numbers)
Decimal (Decimal)
16 bytes
Integer and floating-point numbers scaled by a factor in the range from 0 to 28.

10. The characters that define the type of a variable
1. % - Integer 2. & - Long 3. ! – Single 4. # - Double 5. $ - String

11. Examples of the declare statements
The declare statement (DS) defines a variable, the data type of the variable and optionally, its initial value.
DS begins with a keyword Dim.
Dim a As Integer, b As Long // Dim a%, b&
a = 247
b = 52
Dim c As Integer = // Dim c%= 32768
Dim d As Single = 2.78 // Dim d! = 2.78
Dim e As Double= 3.14 // Dim e# = 3.14

12. String data type Type “String” stores 2 billion characters (about 2GB)
Examples of the declaration:
Dim word As String // or Dim word$
word = “disambiguation”
Dim word As String = “disambiguation” or
Dim word$= “disambiguation”

13. Date data type
Store date values that may include a time (or not), and they are declared with the Date data type:
Dim expiration As Date
expiration = #01/01/2010#
expiration = #8/27/1999 6:27:11#
expiration = #July 2, 2011#
expiration = Today()

14. Control Statements or Flow Control Statements
Decision Statements
If ... Then
If ... Then ... Else
Select Case
Loop Statements
For ... Next
Do ... Loop
While ... End While

15. If ... Then Statement
The If...Then statement tests an expression, which is known as a condition. If the condition is True, the program executes the statement(s) that follow the Then keyword up to the End If statement, which terminates the conditional statement.
The If...Then statement can have a single-line or multiple-line syntax.
Single-line syntax:
If condition Then statement
Multiple-line syntax:
If condition Then
‘Statement(s)
End if

16. If ... Then ... Else Statement
A variation of the If ... Then statement is the If ... Then ... Else statement, which executes one block of statements if the condition is True and another block of statements if the condition is False
The If...Then statement can have (again) a single-line or multiple-line syntax.
Single-line syntax:
If condition Then statementblock1 Else statementblock2
Multiple-line syntax:
If condition Then
statementblock1
Else
statementblock2
End if

17. If ... Then ... Else statement . . .
A third variation of the If ... Then ... Else statement uses several conditions, with the ElseIf keywords:
If condition1 Then
statementblock1
ElseIf condition2 Then
statementblock2
ElseIf condition3 Then
statementblock3
Else
statementblock4
End If

18. Select Case Statements
The Select Case structure evaluates a single expression at the top of the structure. The result of expression is then compared with several values; if it matches one of them, the corresponding block of statements is executed.
Select Case expression (selector)
Case value1
statementblock1
Case value2
statementblock2 .
Case Else
statementblockN
End Select

19. For ... Next loops
For counter = start To end [Step increment]
‘statements
Next [counter]
In executing a For...Next loop, VB does the following:
Sets the counter variable equal to start variable
Tests to see whether counter is greater than end. If so, it exits the loop without executing the statements in then loop’s body.
Executes the statements in the block
Increases the counter variable by amount specified with the increment argument following the Step keyword.
Continues with step 2.

20. Do...Loop
The Do...Loop statement executes a block of statements for as long as a condition is True or until a condition becomes True.
To execute a block of statements until a condition is False, use the following syntax: Do
statementblock
Loop While condition

21. Do...Loop
To execute a block of statements until a condition becomes True, use the following syntax:
Do Until condition
statementblock
Loop

22. While Loops
The While...End While loop executes a block of statements as long as condition is true.
The loop has the following syntax:
While condition
statementblock
End While

23. How to repeat forever?
Do ‘statements-block Loop While 1=1 End While While True

24. Exit from “forever-loop”?
Do ... If condition Then Exit Do Loop While 1=1 If condition Then Exit While End While While True