Introduction about Visual Basic

VISUAL BASIC : VISUAL BASIC Introduction About Visual Basic

Presented by R.SHANTHIVICTORIA : Presented by R.SHANTHIVICTORIA

INTRODUCTION : INTRODUCTION What is Visual Basic? Event Driven Programming Language Responds to user actions Interpretative Programs run as you write them Object Oriented (somewhat) Objects know how to react Emphasis on the Graphical User-Interface (GUI)

Graphic User Interface : Graphic User Interface Graphic User Interface (GUI) comprises Forms Controls Event-driven programming

Object-Oriented & Event-Driven Concepts : Object-Oriented & Event-Driven Concepts Object-Oriented Programming (OOP) Objects (nouns) controls Properties (adjectives) form1.Caption Methods (verbs) debug.print Event-Driven Programming User can press keys and click on various buttons and boxes in a window.

Versions of Visual Basic : Versions of Visual Basic Learning Edition Professional Edition Enterprise Edition

Visual Basic Projects : Visual Basic Projects Visual Basic projects create several files Project file: .VBP Holds the names of other files in the project Form files: .FRM Each form is saved as a separate file Form file contains a description of a form's objects and the Basic code attached to a form Standard code module: .BAS (optional) Custom controls: .OCX (optional) If you include controls that are not part of the standard control set. Form information: .VBW

The Visual Basic Environment : The Visual Basic Environment Form, Project Explorer, Properties, and Form Layout Windows Toolbox Toolbar, Form location & size information

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The Toolbox : The Toolbox Toolbox contents vary based on which version of Visual Basic you are running. Toolbox contains a standard set of controls to place on a form.

The Visual Basic Toolbar : The Visual Basic Toolbar The buttons on the toolbar are shortcuts Toolbar buttons are a quick way to activate frequently used commands Each button stands for a command that you can also select a the Visual Basic menu

FEATURES OF VB : FEATURES OF VB DATA ACCESS OLE USER CONTROLS VERSION INDEPENDENT

Slide 13 : DATA ACCESS It allows the user to manage the data from database systems like (MS Access,Oracle,etc.)Keeping visual basic as front end. OLE(OBJECT Linking Embedded) It allow the user to use the functionality provided by other applications like Flash, Adobe Packages, Macro Media, etc., besides Microsoft packages and other windows application.

Features of VB(Continued..) : Features of VB(Continued..) User Controls(Active X) Provides the easy way to create new controls as per the requirement and can be incorporated for various development in VB Version Independent Any finished application in VB Programming Language is a true file that uses a run time file, so that the user can freely distribute to any windows operating machines

Where VB can be used : Where VB can be used To create small utility for yourself. An applicatioon for department, workgroup,large enterprise-wide system. To create multimedia applications. To create Database applications on Client/Server Technology.

DATA TYPES : DATA TYPES Data types-control the internal storage of data in Visual Basic. How do we associate a type to a variable? VB does this automatically. By default, Visual Basic uses the Variant data type. But programmers can always associate variables to a type explicitly.

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STRINGS : STRINGS A number or a letter represented with double Quotation is called as String. In VB,there are lot of inbuilt string function are available to make the application with more interactivity.

STRINGS FUNCTIONS : STRINGS FUNCTIONS

STRINGS FUNCTIONS(continued) : STRINGS FUNCTIONS(continued)

VARIANT : VARIANT Variant in VB is introduced as a flexible data type that could hold any datatype. Data of any data type Used when datatype is unknown.

THE EVOLUTION OF VARIANTS : THE EVOLUTION OF VARIANTS

TYPES : TYPES

CONSTANT : CONSTANT The term constant implies the values remain constant throughout the execution of an application.

CONSTANT-Intrinsic & Named : CONSTANT-Intrinsic & Named Constant that we define for program use are called named constant. Constant that are built into VB are called Intrinsic Constant. They use a two character prefix to indicate the source DAO means Data Access Object

Syntax for declaring a Constant : Syntax for declaring a Constant [Public/Private]Const = Constant name- Should be a valid name As Type-Data Type Expression –It is the numeric or the string value that has to be assigned to the constant.

BENEFITS OF USING A CONSTANT : BENEFITS OF USING A CONSTANT No need to remember a specific constant values throughout the program. That constant can be used wherever the constant is referred in that program. Once the value of constant is changed in the declaration section of the program,all reference to change it automatically.

Some of the built-in constants that can be used in string variables. : Some of the built-in constants that can be used in string variables.

Some of the built in constants for KeyCodes : Some of the built in constants for KeyCodes

Some of the Visual Basic Constants for the button argument : Some of the Visual Basic Constants for the button argument

DATE FUNCTIONS : DATE FUNCTIONS Known as Internal Function Used to display System Date and System Time.

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ARRAYS : ARRAYS An array is set of similar items. All items in an array can have same name . Array allow you to a series of variables of the same name with an index. In Visual Basic, we refer to each element in an array through an index e.g. name(0), name(1), .., name(n).

syntax: : syntax: Dim As Examples: a.�� Dim grade(7) As Integer b.�� Dim grade(7) As Integer, name(7) As String Example a. tells the compiler to reserve six elements for array grade of type Integer.� The value 7 tells defines the upper bound of the array. The compiler allocates 7 �cells� of equal memory sizes with indices starting at 0 (the lower bound) until 6.

WHERE WE CAN USE ARRAY : WHERE WE CAN USE ARRAY Referencing , Manipulating ,etc., are made easier by array. It is a foundation for the Database Technique.

Rules For Indexing : Rules For Indexing Index number should be nonnegative integer. It should not start with 0. Any constant names can be used as an index. Should be given in rounded brackets(). Index number is also called as Subscript.

Types of Arrays : Types of Arrays Single Dimensional array Multi Dimensional Array Dynamic Array

Single Dimensional Array : Single Dimensional Array This type of array having only one subscript. Example: Dim Var(10) as integer Description: Var(10) - it is an array name 10 - it is the index Integer –is the type of data you are going to store in all the variables of array.

Multi-Dimensional Array : Multi-Dimensional Array This has more than 2 subscripts. You should write the number of For Loops that match with the number of Subscripts. Every dimensional index variable should be unique.

DYNAMIC ARRAY : DYNAMIC ARRAY Dynamic arrays are flexible arrays. Their size can be changed during the course of the program execution. Dynamic arrays are very useful when you do not know how many elements to store in the array during development (programming) time.

example : example A dynamic array is not given a size when declared.� For example: Dim student() As String You can resize the array at runtime through the statement: ReDim student(8) ReDim must be written within procedures.� You can ReDim an array many times.� It can also be used to change the index bounds.� The statement Redim student(3 to 10) changes the lower and upper bound to 3 and 6, respectively.

NOTE : NOTE When ReDim is used, all the contents of the array are erased.� Numeric arrays are initialized to 0 and Strings to a zero-length String.� If you want to retain the values, use the keyword Preserve as in the following statement: ReDim Preserve student(8)

CONTROL ARRAYS : CONTROL ARRAYS With control arrays, you can group related controls and refer to each control by an index. We then refer to the TextBoxes as txtName(0), txtName(1), �, txtName(9).

LOOPING : LOOPING What is Looping? Looping is a process which comprises of instructions that are executed repeatedly until some condition is satisfied. Two Types: Determinant Loop Non -Determinant Loop

Slide 45 : Determinant Loop: It is called as finite loop which means there will be a end point for the loop. Non- Determinant Loop: It is called as infinite loop which means there will not be a end point for the loop.

Loop structures in VB : Loop structures in VB 1.For-Loop 2.Do….While 3.Do…..Until

FOR-LOOP : FOR-LOOP This type of loop can be called as counter –style loop process. It executes the statements until it reaches the end value. Hence this loop structure is Determinant type.

For Loop(Continued…) : For Loop(Continued…) Syntax: For = To Step One or more VB statements Next

For Loop(Continued…) : For Loop(Continued…) Example: Dim I as Integer Dim N as Integer N=0 For I=1 to 100 N=N+10 Next I

Do While (or) Do Until : Do While (or) Do Until The do loop allows to repeat the code while or until a condition is met. This do loop will continue its process until a given condition is true. Once the condition is failed the process will not be repeated. This type of loop structure is non-determinant.

Do while : Do while Syntax: Do while() Statements Loop Example: C=0 I=1 Do while (I<10) C=C+I I=I+1 loop

Do Until : Do Until Syntax Do until() Statements loop Example: C=0 I=1 Do until (I<10) C=C+I I=I+1 loop

THANK YOU : THANK YOU 53