August 2008

Subject Code: BT0040-1Subject Name: Visual Programming with VB

Course Name: BSc IT New Semester: II Credits: 4

Marks: 40

Q.1 Write about the Visual Basic Application Development Life cycle with a sample Forms development for performing integer arithmetic operations.

Ans. Visual Basic Application Development Life cycle: These are the necessary steps to create a visual basic program. Programmers call these steps as ‘development cycle’.

Decide what you want the computer to do.

Decide how you want your program to look on the screen. (The appearance of your program is called the user interface)

Draw your user interface by using common components, such as windows, menus and command buttons. (The components of user interface are called objects or controls).

Define the name, color, size and appearance of each user interface object. (An object’s characteristics are called properties).

Write instructions in BASIC to make each part of your program do something. (BASIC instructions are called commands).

Run your program to see whether it works.

Fix any errors (or bugs) in your program.

Q.2 Discuss the following: Form Modules Standard Modules Class Modules

Ans. Form modules: Form modules (.FRM extension) are the foundation of any VB application. They can contain graphical descriptions of the form and its controls, including their property, settings. They can also contain form level declarations of type constants, variables and external procedures, procedures that handle events and general procedures. Virtually everything that applies to class module applies to form module. Forms are just class modules that can have controls placed on them and display a form window. Forms are part of our application that are visible to users at run time.

Standard modules: Standard modules (.BAS extension) are containers for procedures and declarations, commonly used by other parts of our application. They can contain global or module level declarations of types, constant, variables, external procedures and global procedures.

Class modules: Class modules (.CLS extension) are foundation of object oriented programming in VB. We can write code in class modules to create new objects. These new objects can include our own customized properties and methods, although custom objects can not have their own events. All the properties and method we create can also be used by other objects, in our application. We can also use the keyword, New to create multiple copies of our objects.

Q.3 Create a Menu Interface in Visual Basic which performs the same functionality of MS – Word File menu.

Ans.

Q.4 Develop a University Database using MS – Access. Create appropriate form based interfaces to access the data using controls in the tool box.

Subject Code: BT0040-2Subject Name: Visual Programming with VB

Course Name: BSc IT New Semester: II Credits: 4

Marks: 40

Q.1 Discuss the following: Visual Basic Editions Object Naming Conventions Event Procedures

Ans. Visual Basic Editions: Visual Basic software comes in three editions:

Learning Edition: which includes the Visual Basic development environment and use of standard tools to develop applications

Professional Edition: It is used by computer professionals as it supports the tools to develop ActiveX and internet controls.

Enterprise Edition: which includes all the features of professional edition as well as MS Visual Source safe for source code control and Automation and Component manager?

Object Naming Conventions: When we create an object, VB sets its name property to a default value. It is good practice to change their Name properties to something more descriptive, when there are several controls of the same type. The following naming convention for VB objects is a common practice.

Object Prefix ExampleForm Frm frmFileOpenCheckbox Chk chkVegCombo box Cbo cboLanguageCommand Button Cmd cmdCancelData Dat datBibilioDirectory list box Dir dirSourceDrive list box Drv drvTargetFile list box Fil filSourceFrame Fra fraCourseHorizontal scroll bar Hsb hsbVolumeImage Img imgIconLabel Lbl lblNameLine Lin linVerticalList box Lst lstInstitutesMenu Mnu mnuFileOpenOption button Opt optSmilePicture box Pic picDiskShape Shp shpCircleTextbox Txt txtNameTime Tmr tmrAlarmVertical scrollbar Vsb vsbRate

Event Procedures: when an object in VB recognizes that an event has occurred, it automatically invokes the event procedure with the name corresponding to the event. Because the name establishes an association between the object and the code, event procedures are attached to forms and functions.

An event procedure for control combines the control’s actual name, an underscore, and the event name. For instance if we want a command button named cmdQuit to invoke an event procedure when it is clicked, use the procedure cmdQuit_Click.

An event procedure for a form combines the word Form and underscore and the event name. If we want a form to invoke an event procedure when it is clicked, we use the procedure Form_Click. Like controls forms do have unique names, but they are not use in the names of event procedure. If we are using the MDI form, the event procedure combines the word MDIForm, an underscore, and the event name as in MDIForm_Load.

Q.2 Discuss the following control structures of Visual Basic with suitable programming examples for each:

If Statements Case Statements Do While Loop For…Next Loop

Ans. IF statements:

If … ThenWe can use either single line syntax or multiple line block syntax.If <condition> Then <statements>It <condition> Then

<Statements>

End If

If … Then … Else

If <condition1> Then [Statements block 1]

[Else If <condition2> Then[Statements block 2]

[Else[Statement block n]]

End IfExample:

Dim marks as integerMarks = val(text1.txt)If marks > 90 then

Text2.txt = “Excellent”Else if marks > 80 then

Text2.txt= “Very good”

Else if marks > 70 thenText2.txt= “Good”

Else Text2.txt = “Average”

End if

Case Statements: A select case statement provides capability similar to the If … then …. Else but it makes code more efficient and readable.

Select case text expression[Case expression list 1

[Statement block 1]][Case expression list 2

[Statement block 2]]

…….

…….

…….

[Case Else[Statement block n]]

End Select

Example:

Dim marks as integerMarks = val(text1.txt)Select case marks

Case is > 90 Text2.txt = “Excellent”

Case is > 80 thenText2.txt= “Very good”

Case is > 70 thenText2.txt= “Good”

Case Else Text2.txt = “Average”

End Select

Do While ….. Loop: Loop structures allow us to execute one or more lines of code repetitively.

DO While <condition>Statements

LoopExample:

Dim k as integerK=5Do while k<10

Text1.txt=kK=k+1Loop

For…Next Loop: this loop structure is used to execute the statements a specific number of times. For loop uses a counter variable that increases or decreases in value during each repetition of the loop.

For [counter] = start to End [step increment]

Statements

Next [counter]Example:

Dim k as integerFor k=1 to 10Text1.txt=kNext k

Q.3 Create an MDI Application of your own in Visual Basic with at least 3 child forms under the Parent Form.

Ans.

Q.4 Discuss with the help of a programming example all the features of Data Access Objects (DAOs) in Visual Basic

Ans. Data Access Objects: one of the tools available in VB to access databases programmatically is data access objects (DAO) programming interface. Using data access objects we can create databases and build full featured applications that access existing databases in many popular formats, including MS- access, Btrieve, dBASE, MS- foxpro, Paradox as well as ODBC client/ server databases like MS SQL server.

Example:

Dim myWs As WorkspaceDim myDb As DatabaseDim myTd As TableDefDim myFields(5) As FieldDim mySet As RecordsetDim Total As Long

Sub Form_Load()

Set myWs = DbEngine.Workspaces(0)

Set myDb = myWs.CreateDatabase (“D:\VB\Mahe\employee.mdb”, dbLangGeneral)Set myTd = MyDb.CreateTableDef(“Empmast”)Set myFields(0) = myTd.CreateField(“emp_no”, dbingeter)Set myFields(1) = myTd.CreateField(“emp_name”, dbText,20)Set myFields(2) = myTd.CreateField(“dept_no”, dbingeter)Set myFields(3) = myTd.CreateField(“salary”, dbSingle)Set myFields(4) = myTd.CreateField(“Jjoin_date”, dbDate)

myTd.Fields.Append myFields(0)myTd.Fields.Append myFields(1)myTd.Fields.Append myFields(2)myTd.Fields.Append myFields(3)myTd.Fields.Append myFields(4)MyDb.TableDefs.Append myTdMsgBox “DataBase Created”

End Sub

Private Sub cmdEdit_Click()If Val(txtNo.Text) > 0 ThenmySet.Editframove.Visible = FalsefraOther.Visible = FalsecmdEdit.Visible = FalsecmdAdd.Visible = FalseElseMsgBox(“nothing to edit”)End if

End Sub

Private Sub cmdEnd_Click()mySet.ClosemyDb.closeSet myDb = nothingEnd

End Sub

Private Sub Form_Load()Set myDb = OpenDatabase(“D:\VB\Mahe\employee.mdb”)Set mySet = myDb.OpenRecordset(“Empmast”, dbOpenDybaset)

End Sub