1. Visual Basic .NET Fundamentals Prepared By: Rekha (Teaching Assistant) Govt. PG College, Rajauri

2. Objectives
Use primitive data types, naming conventions, and style rules
Understand and apply the control structures supported in Visual Basic .NET
Explain the objects and techniques involved in the creation of a Multiple Document Interface (MDI) application
Understand the purpose and uses of these new Windows Forms controls: TabControl, ComboBox, CheckBox, GroupBox, and RadioButton

3. Using Primitive Data Types, Naming Conventions, and Style Rules
Literal
Has the face value of each occurrence
Constant
Is assigned a literal value that does not change
Variable
Is a symbolic reference to an address in memory
Values stored memory block can change during program execution
Naming Conventions
Facilitate program readability, understandability, and maintainability
Programmer-supplied names must be meaningful
Variable names are mixed case and consist of a prefix and a meaningful name

4. Using Primitive Data Types, Naming Conventions, and Style Rules (Continued)
Example variable declarations
Dim mdecInterestRate As Decimal - A module-level decimal
Public pastructUser - A public array of structures
Static stintLineCtr - A static integer
Dim strMessage - A dynamic local string
Naming constants
Const DAYSINWEEK = 7
Naming functions
Private Function GetNextRecord()
Public Sub FindLastName()
Protected Sub EnableDisableTextboxes(vbln As Boolean)
Naming classes
Public Class Student
Public Class AcademicProgram
Naming controls
Controls have a prefix indicating the control’s class

5. Coding Conventions and Style Rules
Purpose: to increase code readability, and, therefore, make it easier to revise and debug
Using indentation
To visually identify groups of related statements
Declaring variables at the lowest level
If variable needed only inside a procedure, declare it inside that procedure
If variable needed only in one form, declare it at form level in that form
If a variable is needed only inside a standard module, declare it as a Private variable inside that module
Using constants
Use constants rather than numeric values when possible
Constants improve program readability and also facilitate program maintenance
Writing code that is easy to read
Try to write code that is easy to read, follow, and understand

6. Control Structures and Structured Programming
A method of controlling the execution sequence of instructions at runtime
Characteristics of structured programs
Limited to sequence, selection, and iteration, with unlimited nesting
Every procedure has a single entry point and a single exit point
Using stepwise refinement, programs are broken down logically or functionally into relatively small blocks of code
Variables are declared at lowest possible level
Global variables are used minimally, if at all
Stub
A placeholder for a section of code that will be developed later

7. Visual Basic .NET Control Structures
Sequence structure
One statement after another
Selection structure
Includes the If statement, Select Case statement, Immediate If function, and Try statement
Iteration structures
Provide for the repeated execution of a statement block
If statement
Allows you to specify a condition or test, and if that condition is met, to then execute one or more imperative statements

8. Logical Operators And Or AndAlso OrElse Xor
The result is True only when condition A and conditionB are both True Or
The result is True if at least one of conditionA or conditionB is True
AndAlso
The result is True only when conditionA and conditionB are both True
OrElse
Xor
The result is True only when one and only one of conditionA and conditionB is True

9. Truth Table for Visual Basic .NET Logical Operators

10. Visual Basic .NET Control Structures (Continued)
Select case
Useful when the evaluation of a single expression can determine multiple paths
Immediate If (IIf)
Examines <condition> and returns <resultA> if the condition is True; otherwise, it returns <resultB>
Syntax: <variable> = IIf(<condition>, <resultA>, <resultB>)
Try … Catch … Finally
Provides a structured programming solution to the problem of error trapping
Do loops
Principal form of externally controlled loops
Pretest loop
Posttest loop
While test
Until test

11. For Loop Internally controlled loop Requires
Loop control variable (LCV)
Initial value for the LCV
Limit value for the LCV
Step value
Test to determine whether the LCV’s limit value has been reached (after which the loop is exited)

12. Using a For Loop for a Sequential Search

13. THANK YOU