Thursday, July 24, 2008

VB6.0 vs. VB.NET

.NET Platform
To understand VB.NET, we must first understand the .NET platform.

 .NET Framework: a set of approximately 3500 classes.
 These classes are divided into namespaces that group similar classes together.
 For organization, each class belongs to only one namespace.
 Most classes are lumped into a name space called System

System.Data contains classes used for accessing data in a DB
System.XML contains classes used for reading/writing XML
System.Windows.Forms contains classed used for
System.Net contains classes for communicating over the network.

 Essentially MS performed a massive re-organization of all the classes, no longer leaving methods or functions without clearly belonging to a specific class. For example, note the difference between Messagebox() in VB6.0 and Messagebox.Show() in VB.NET (to be discussed later).


Visual Studio.NET
 Visual Studio.NET is the next version of IDE from MS.
Note: VS.NET does require at least double its system requirements to function feasibly.
Note: VS.NET can be installed on the same machine as VS 6.0. Many have warned against it, yet personal experience has proven otherwise.

 VS.NET comes standard with VB.NET, C# (C-Sharp), and VC++.

 VS.NET supports more than 20 languages.

 All languages compile to .EXE and .DLLs containing Common Intermediate Language (CIL or IL), not machine native code. C++ is the only exception offering an option to compile to machine native code.

 These CIL executables then run in the Common Language Runtime (CLR) using a Just-in-Time (JIT) compiler. Note the similarity of .NET to JAVA and JVM.

 The JIT compiler dynamically converts the IL to machine native code during execution, and caches the native code for subsequent use.
Advantages of CLR

 The JIT allows code to run in a protected environment as managed code. The protected environment polices each application to run in its own memory segment. This prevents a developer from shooting himself in the foot, but it also limits control.

 Using a JIT allows the IL code to be hardware independent. As long as the .NET framework is installed, the IL code can be executed.

 The CLR also allows for enforcement of code access security.

 Verification of type safety.

 Access to Metadata (enhanced Type Information)

 Support for developer services (profiling, debugging)

 Interoperation between managed code, COM objects, pre-existing DLLs (unmanaged code and data).
.NET components can access COM components.
COM components can access .NET components by registering the .Net assembly using the regasm.exe utility.

 .NET provides a unified Programming Model
Then: VB for RAD, VC++ for MFC/ATL, ASP for code embedded web pages
Now: Any language to handle any .NET functionality.




.NET Framework supports Web Standards
HTML
XML
XSLT
SOAP
WSDL for Web Services



ILDASM
The IL can be modified using Intermediate Language Dis-assembler (ILDASM). ILDASM is a tool used to properly display IL in a human readable format. A developer can then add remove code as needed for fine tuning. Many developers speak highly of this method for fine tuning code.


Visual Studio.Net vs. Visual Studio 6.0
 Syntax of event handling methods:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

 In VS.Net CTRL-ESC opens inteli-sense for easy searching of methods

 With VB6.0, project files were very simple:
.VBP
.VBW
.CLS / .FRM / .RES

 File structure in .NET varies greatly from VB6.0 file structure.

Note: For a tree diagram of the file structure, enter the following in a DOS prompt.
C:\>Tree C:\VBPrograms\WindowsApplication1 /F /A

C:\VBPROGRAMS\WINDOWSAPPLICATION1
| WindowsApplication1.vbproj
| AssemblyInfo.vb
| Form1.vb
| Form1.resx
| WindowsApplication1.vbproj.user
| WindowsApplication1.sln
|
+---bin
| WindowsApplication1.exe
| WindowsApplication1.pdb
|
\---obj
\---Debug
| WindowsApplication1.Form1.resources
| WindowsApplication1.pdb
| WindowsApplication1.exe
|
+---temp
\---TempPE


 Both .EXE are executable, pending the user has .NET framework installed.

 Use of “Imports System.IO” imports the System.IO. This is similar to the With block code.
Application Deployment
 Use XCOPY
 Downloading code is also available.
 No need to register components.
 Can run multiple component versions simultaneously.
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VB Questions (General)



  • Dim x, y as integer. What is x and y data type?

    • X as variant and y as integer.

  • What is the size of the variant data type?
    •

    Variant variable size = 22 + Actual data type size.
  • What is the return type of Instr and Strcmp?

    • Instr – integer (Numeric position)
    Strcmp - integer ( if both the string are equal they result = 0)
    Strcmp (Str1, Str2, Comparetype)
    Comparing mode = 0 – Binary Comparing

    1 – Textual Comparing

  • What is the max size allowed for Msgbox Prompt and Input Box?

    • 1024

  • Max label caption length. –

    • 2,048

  • Max Text box length –

    • 32,000

  • Max Control Names length –

    • 255.

  • Extension in Visual Basic

    • Frm, bas, cls, res, vbx, ocx, frx, vbp, exe

  • What is frx?

    • When some controls like grid and third party control placed in our application then it will create frx in run time.

  • Name some date function

    • Dateadd(), Datediff(), Datepart(), Cdate()

  • what will be the result for

    • 15/4 = 3.75 and 15\4 = 3

  • What is keyword used to compare to objects?

    • ISOperator – Returns Boolean.

  • How many procedures are in VB?

    • 2. function and sub procedures (Ask what is the diff. Between them?)


  • Where will we give the option explicit keyword and for what?


    • In the general declarations section. To trap undeclared variables.



  • What is Friend Variable?

    • Scope sharable between projects.


  • What is binding? What are types of binding?

    • Assigning variable with defined memory space.
    Late Binding - Memory size is allotted in later stage.
    Ex:- Dim x as object
    Early Binding - Memory size is allotted while declaring itself.
    New Key word is important.
    Ex:- Dim x as New Object

  • What is the difference between Property Get, Set and Let.

    • Let – Value is assigned to ActiveX Object from the form.
    Let – Value is retried to ActiveX Object from the form.

  • What is Mask Edit and why it is used?

    • Control.     Restricted data input as well as formatted data output.


  • Drag and Drop state numbers and functions.

    • State 0 – Source control is being dragged with the range of a target.
    1 – Out of the range of a target.
    2 – One positon in the target to another.


  • What are the type of validation available in VB?

    • Field, Form


  • With in the form we want to check all the text box control are typed or not? How?

    • For each currentcontrol in controls
    if typeof currentcontrol is TextBox then
    end if
    next


  • What is the result of Null * Any value = 0 (Zero).


  • What is control array and How many we can have it with in the form?

    • Group of control share the same name. Max 32, 767.


  • What is the default model of the form? And what is it number?


    VbModaless – 0 (Zero) – We can able to place another window above this form.


  • Suppose from form1 to form2 object property settings will arise to ?

    • Invalid procedure call or argument (Run time error – 5)
  • What is the diff between the Std and Class Module?

    • Std Global with in the project. Cls Global through out the all project only thing is we want to set the type lib. Class Modules can be Instantiated.

  • Different type of Instantiation?

    • Private –     Only for the Specific Module.
    Public not creatable – Private & Public
    Multi Use - Variable we have to declare.
    Single Use – Not possible through dll.
    Global Multiuse – Have variable not Required to Declare.
    Global Single Use - " Only for exe.

  • How to declare Dll Procedure?

    • Declare function "" lib "" Alias "" (Arg, …..) as Return type.


  • What is MDI form? MDI Styles?

    • We can have only one MDI form for a project. Multiple Document Interface. This form type is VBModal. We have set the Child property of the forms to True to place forms inside this MDI.
    Style availables 1. VbCascade 2. VbTitle Horizontal

  • How many images can be placed in the image list ?

    • 64
  • What is Inprocess and Out of Process?

    • Inprocess –     It will run with in the memory. ( Local Machine).
    Out of Process – It will run out of the memory Normally in the server side.

  • Diff type of Datatypes?

    • LOB (Large Object Data type).
    CLOB (Stores Character Objects).
    BLOB ( Store Binary Objects such as Graphic, Video Chips and Sound files).
    BFILE(Store file pointers to LOB It may Contain filename for photo’s store on CD_ROM).

  • What is Zorder Method?

    • Object.Zorder = 1 or 0 Place a Specified mdiform form or control at the font or back of the z-order with n its Graphical Level.
  • What is diff between the Generic Variable and Specific Variable?

    •

    Generic Variable:

    Create Object Ex:-Ole-Automation . No need refer the object library.

    Specific Variable:

    Binding Procedure Early and Late Binding ( Can be Remove from the Memory).

  • What are properties available in Clip Board?

    • No Properties Available. Only the methods they are SetText, GetText, Setdata(), Getformat(), Clear.

  • What is Dll?

    • Libraries of procedures external to the application but can be called from the application.

  • What is Tabstrip control? What is the starting Index value? How to locate it?

    • It is tab control to place our controls with in the form in multiple sheets.
    Index starts with 1. And to identify

    If Tabstrip1.SelectedItem.Index = 1 Then
    …..
    End if

  • Why we use Treeview Control?

    • To list the hierarchial list of the node objects. Such of files and Directories.

  • Why we need OLE-Automation?Advantages?

    • Enables an application to exposes objects and methods to other Applications.
    No need to reserve memory. No need to write functions. Object library that simplify programming tasks. i.e., No need to Object library. (OLB, TLB).

  • What is the diff between the Create Object and Get object?

    • Create Object -     To create an instance of an object.
    Get Object – To get the reference to an existing object.

  • Have you create Properties and Methods for your own Controls?

    • Properties –     Public variable of a Class
    Method –     Public procedure of a class

  • What is Collection Objects?

    • Similarly to arrays but is preferred over an array because of the following reasons.

    1. A collection objects uses less Memory than an array.
    2. It provides methods to add and delete members.
    3. It does not required reason statement when objects are added or deleted.
    4. It does not have boundary limitations.

  • What is Static Variable?

    • Its Scope will be available through out the life time.

  • Private Dim x as integer.

    • Private cannot be used in front of DIM.

  • What is Implicit?

    • Instance of specific copy of a class with its own settings for the properties defined in that class.
    Note: The implicity defined variable is never equal to nothing.

  • What are the scope of the class?

    • Public , private, Friend

  • Can we able to set Instancing properties like Singleuse, GlobalSingleuse to ActiveXDll?

    • No.

  • In project properties if we set Unattended what is it mean?

    • This cannot have user interface. This can be used for the COM creation.

  • What are the Style Properties of Combo Box?

    • Simple, Dropdown list – We can type and select.
    Dropdown Compo – Only Drop Down.

  • What are the Style properties of List Box?

    • Simple –Single Select , Extended. – Multiple Select.

  • What are the different type of Dialog Box?

    • Predefined, Custom, User Defined.

  • What is Parser Bug?

    • It is difficult to use database objects declared in a module from within a form.

  • What is the Dll required for running the VB?

    • Vbrunxxx.dll

  • Can We create CGI scripts in VB?

    • Yes.

  • How to change the Mouse Pointer?

    • Screen.MousePointer = VBHourGlass/VBNormal.

  • How to check the condition in Msgbox?

    • If(Msgbox("Do you want to delete this Record",VbYesNo)=VbYes)Then End if
    Labels:

    Thursday, July 17, 2008

    vb questions 11

    LockEdits property to False - Optimistic locking - update error
    What kind of error is the most expected with optmistic lock? Data changed;
    operation stopped
    Empty value ByVal 0&, vbNullString
    Char ByVal a As Byte
    Asciiz String ByVal as String
    2 deferent DLLs from 2 vendors - declare private or Use the alias keyword
    Adressof MyProc - Correct
    In which case is a new object created? set x=new form1
    Which Option will not allow to create instances : set Public to FALSE
    type library and New Keyword are required for Early Binding.
    How to raise an event? First to declare it, use the Event keyword,
    then Raise it.
    Ambient - change the background color of the control on the container
    Create a license package file with a utility from the LPK_TOOL directory.
    Run-time license: Application Setup Wizard
    Design-time license: Application Setup Wizard
    Internet license: LPK_TOOL.EXE, and create a reference to the .LPK file
    To navigate between the two ActiveX documents, use the HyperLink object and
    its NavigateTo method. Use the GoBack or GoForward methods to go backwards
    or forwards through the History list. WebBrowser Object - Use GoHome and
    GoSearch
    Hyperlink offers a help option on Web.
    Data persistence is the ability of a component to store and retrieve data.
    The Internet Explorer 3.0 (and higher) and Microsoft Office Binder allows
    you to write to a file using the PropertyBag.
    Create separate secondary .cab files to reduce download time.
    Which two project types can contain an ActiveX Document? ActiveX Dll,
    ActiveX Exe.
    What project types can have ActiveX documents? - All that can be a container
    How to convert an ActiveX.DLL to multithread? - Make it ActiveX. EXE
    Advantages of Using ActiveX Documents - Support for the Hyperlink object and
    AsyncRead method
    Which project template would you select to build an in-process code (ActiveX
    Document DLL)?
    The AsyncRead method initiates an asynchronous download.
    Datatypes to be downloaded: files, pictures, byte arrays
    Which 2 actions may disqualify a component for being marked as safe for
    scripting? inserts in/reads from registry
    When an error occurs in a component, call Err.Raise number.
    Err.Source returns the name of the object that generated an Error.
    Command1_Click() AND Command2_Click() call each other - Out of Stack Space
    error
    Which task can you accomplish by packaging in .cab file? register on users
    computer
    Q: There is a www server application that uses ActiveX controls you
    developed. When the application page is browsed with IE it does not show
    the ActiveX control. What may be happening?
    A1: No Internet download license file on the web server
    A2: Options in the Application Setup Wizard were not used correctly
    Q: Where do you define conditional compiling variables?
    Command line
    Project Properties dialog box (under the Make tab)
    In code
    •Q: Difference between debugging an ActiveX control project and an
    in-process component?
    A: The component code can run while the client is in Design mode
    •Q: When testing a UserControl, you add a standard.exe to your project
    group. UserControl in the Toolbox is dimmed. What should you do?
    A: Close the UserControl designer and then test again
    How to view contents of the Variant?
    - Use Debug.print
    - Look at the Locals window
    Q: What cannot be done when an Internet Control is packaged. (Choose Two)
    A: Write to a file
    Read from the registry
    Q: How can you build ActiveX components for Internet distribution?
    A: Use the Application Setup Wizard and pick the appropriate options
    ------------------------------------------------------------------------
    Q: Which function can the Setup Wizard (Enterprise Ed.) of VB 5 perform in
    addition to installing your ActiveX EXE project?
    A: install your project as an ActiveX shared component
    Q: What does locales show in different contexts?
    A: In Visual Basic, many functions use the user's system locale, which uses
    the Control Panel settings provided by the operating system to automatically
    determine the conventions at run time. These functions are called
    locale-aware functions.
    Q: When should you use public variables instead of property procedures for
    read-write properties?
    A: The property is a String data type, and there is no constrain on the size
    or value of the string.
    Q: Where and why to use Friend methods and properties
    A: The combination of public to classes in the same project and private to
    the external.
    Q: You have a Data Control with Bound Controls. You want to provide the
    ability to abort changes in the record currently being edited and to
    refresh the bound controls. How?
    A: Only invoke the UpdateControls method for the Data control.
    •Q: A list-box is used as a constituent control. The design window is
    closed and the control inserted on a form in another project. The user
    then sets the sort property of the control which in turn sets the sort
    property of the control. Why does the error occur?
    A: Compile the control project ?
    Q: How to set properties for the individual Column objects?
    A: You must make the DBGrid control UI-active: Select the right mouse
    button, and choose Edit. Then use pop-up menu.
    Q: How to remove column header?
    A: object.ColumnHeaders = False
    Q: How to refer a colmun?
    A: object.ColIndex [= value]
    This property returns the zero-based index of a column within the Columns
    collection.
    Q: How to check the value of a specific field in the current record?
    A: MyString = Data1.Recordset.Fields("Title").Value
    Data1.Recordset("PubID") = 43' Set the field values.
    Data1.Recordset("PubID") = "12345" ' Change the value.
    What are the benefits of Forms collection?
    - Allows faster unloading of all forms in the project *
    - Faster access
    - Standardized mechanism for tracking multiple instances of a form *
    - Group forms & drag the group
    How to handle resizing of the label in a UserControl?
    During design time - Label1_Resize
    During run-time – UserControl1_resize
    How to refer to the contents of the child of the selected node of a TreeView?
    Set nodChild = TreeView1.Nodes(TreeView1.SelectedItem.Index).Child
    •
    •tvwMyTree.Nodes(10).Children ‘ return the number of children
    tvwMyTree.Nodes(10).Parent.Text ‘ return the Text of Parent
    What properties can you set while using the Add property for a list view?
    •ColumnHeader object.Add(index, key, text, width, alignment, icon)
    Which type of Instancing should you use for the class module?
    A. private
    B. multiUse
    C. GlobalMultiUse
    D. PublicNotCreatable *
    Labels:

    vb questions 10

    Q: Why would you want to set the LockEdits property to False?
    A: Optimistic locking is in effect for editing. The 2K page containing the
    record is not locked until the Update method is executed.
    What kind of error is the most expected with optmistic lock? Data changed;
    operation stopped
    If recordset.lockedits=false, which would be the most like to occur:
    A. update error: record locked on by *
    B. save error: record locked on by
    C. can not read database...
    Incorporate dynamic-link libraries (DLLs) into an application.
    •Declare and call a DLL routine.
    Q: How to declare a DLL with a C Char datatype?
    A: ByVal variable As Byte
    Declare Function Publicname Lib "libname" [Alias "alias"] [Arguments List]
    As Type
    Empty value ByVal 0&, vbNullString
    Char ByVal a As Byte
    Asciiz String ByVal as String
    There are 2 deferent DLL from 2 vendors and the DLL have the same name.
    What must you do to be able to call both functions?
    A. modify function name in one
    B. declare public in separate module use the alias keyword to
    C. declare private rename one function *
    D. Use the alias keyword to rename one function *
    We obtained many DLL functions from different vendors. Two functions happen
    to have the same name but different purposes. What can we do?
    A. Using an alias *
    B. Declaring each Private in separate modules *
    C. Registering one with another name
    D. Modifying the DLL function.
    Pass argument contain address of a Vb subroutine named MyProc to a MicWind
    HPL
    A. Aressof := MyProc
    B. Adressof Me.MyProc
    C. Adressof MyProc *
    D. Adressof (MyProc)
    Which code will create a new instance of object named Form1 in Project1?
    A. Dim Frmx As Form1
    B. Dim Frmx As New Form1 *
    C. Set Frmx = Form1
    D. Set Frmx = GetObject("Project1.Form1")
    How many instances of class1 after running exist after the following code?
    Dim a As Class1
    Dim b As new Class1
    b.MyProperty = 3
    Set a = new Class1
    A. 0
    B. 1
    C. 2 *
    D. 3
    In which case is a new object created? set x=new form1
    Which Option will not allow to create instances : set Public to FALSE
    Create an Automation server that exposes objects, properties, methods, and
    events.
    Q: The differences between early binding vs. late binding
    •A: Late binding occurs when the compiler does not know about an object
    until run time.
    Early binding occurs when Visual Basic knows at compile time exactly which
    interface will be used with an object variable.
    Which two required for Early Binding?
    A. Type library *
    B. Dual Interface
    C. New Keyword *
    D. CreateObject Function
    For Early Binding
    Dim Varnaem as Class
    Set varname = CreateObject(ClassName)
    Create and use an ActiveX control.
    •Declare and raise events.
    How to raise an event?
    First to declare it, use the Event keyword, then Raise it.
    e.g. RaiseEvent ABC (arguments)
    How Project Groups can be used when debugging ActiveX controls(lots of Qs).
    Ambient & Extender
    What is the property of a container that can be used to change the
    background color of the control on the container when the background color
    of the container changes?
    A. Ambient *
    B. Extender
    C. Appearance
    D. Property Pages
    How do you create a license package file containing the licensing
    information for all controls on a Web page?
    A. With the Visual Basic License Manager.
    B. With the CODEBASE parameter of an HTML page'stag.
    C. With the Visual Basic Application Wizard.
    D. With a utility from the LPK_TOOL directory on the Visual Basic CDROM. *
    Q: How to add a control to a web page?
    A: By scripting
    You want to minimize download time for an ActiveX document with several
    components. How package within a .cab file?
    In a single .cab file
    One .cab with ActiveX document. And a second .cab with referenced components
    One .cab with ActiveX document and an INF file that points to individual cab
    files for each component. *
    One .cab with ActiveX document, an INF file that points to a .cab file with
    the referenced components
    Q: How to reduce the time for downloading on Internet an ActiveX component?
    A: Create separate secondary .cab files ???
    Users may already have these secondary .cab files on the system or the
    secondary .cab files can be downloaded from Microsoft's web site.
    Which two project types can contain an ActiveX Document?
    A. Standard EXE
    B. ActiveX Document EXE *
    C. ActiveX Document DLL *
    D. ActiveX Control
    Q: What project types can have ActiveX documents?
    A: All that can be a container
    Q: How to convert an ActiveX.DLL to multithread?
    A: Make it ActiveX. EXE
    Q:Advantages of Using ActiveX Documents (Choose 2).
    Q: What elements of ActiveX Components on a Web page contribute to security?
    •A: When you use ActiveX controls on a Web page, you can implement the
    following security measures:
    •Set the appropriate level of security in Internet Explorer
    •Provide users with information about the author of the control
    •Through digital codesigning
    •Create an Internet download by marking your Controls as safe for
    scripting and initialization
    Which project template would you select to build an in-process code
    (ActiveX Document DLL)?
    Hyperlink object
    Which 2 actions may disqualify a component for being marked as safe for
    scripting?
    A. the component creates a password
    B. the component writes information to a file
    C. the component inserts data in registry *
    D. the component reads information from registry *
    Q: There is a www server application that uses ActiveX controls you developed
    . When the application page is browsed with IE it does not show the ActiveX
    control. What may be happening?
    A1: No Internet download license file on the web server
    A2: Options in the Application Setup Wizard were not used correctly
    What ActiveX can do on WWW?
    A. create licensing files
    B. digital signing
    C. register your control on a user’s computer *
    D. modifying the users internet security settings
    If you want to offer an option in a help menu for users to access your Web
    Site, what ActiveX Document should you use?
    A. Automation
    B. WinSock
    C. Hyperlink *
    D. ActiveX component
    You have an ActiveX document that uses the AsyncRead method to obtain data
    from an intranet location. What type of data does it cannot return directly?
    A. Files
    B. Byte arrays
    C. Pictures
    D. Hyperlinks *
    What is the purpose of the ID parameter in an HTML tag?
    A. Specifies a URL that points to a file containing an implementation of an
    object.
    B. Specifies the object's unique class identifier stored in the system
    registry.
    C. Specifies a URL that points to the name of the object.
    D. Specifies the object name. *
    An ActiveX component connects to a database, the connection to the database
    fails. What to do?
    A. Create an error event
    B. Set err object to false
    C. Call raise method of the err object *
    D. Create a prop name connected that returns false
    Q: An error occurs in a component that you wrote, how to notify client:
    A: Err.Raise number
    Which property of the Err object returns the name of the object that
    generated an Error?
    A. Description
    B. Source *
    C. Number
    D. Helpcontext
    Q: Which code segment would best trap a "division by zero" error handling?
    A: For example: (See Error Handling)
    •Public Sub ProcDivZero()
    On Error GoTo ErrTrapper
    X = 100 / 0
    Exit Sub
    End Sub
    ErrTrapper:
    If Err.Number = 11 Then Debug.Print "Division by Zero Found"
    End Sub
    When the following code executes. What will the user see?
    •Public Sub MyTest()
    On Error GoTo ErrHandler
    Dim X as Integer
    MyProc(X)
    MsgBox "XXX"
    Errhandler:
    MsgBox "YYY"
    End Sub
    Public Sub MyProc(X As Integer)
    On Error GoTo MyprocErr
    X = X / 0
    MyprocErr:
    MsgBox "ZZZ"
    End Sub
    a) "XXX" Only
    b) "ZZZ" Only
    c) "XXX", "ZZZ" and "YYY" Only *
    d) "XXX" and "ZZZ" Only
    Q: What will be shown when this code is executed?
    Private Sub Command1_Click()
    Command2.Value = True
    End Sub
    Private Sub Command2_Click()
    •Command1.Value = True
    End Sub
    A: OUt of Stack Space error
    Q: What will happen if user presses command2?
    Sub Mysub()
    •Static intNum As Integer
    If intNum <= 4 Then
    •Exit Sub
    Else
    •
    •intNum = intNum + 1
    Mysub
    End If
    End Sub
    Private Sub Command2_Click()
    •Mysub
    End Sub
    A: The code will run OK
    Implement Help features in an application.
    You want to use the ShowHelp method to display specific Help file pages for
    your application without declaring a dll. Which object?
    A. App
    B. Menu
    C. MenuLine
    D. CommonDialog *
    Before you use the ShowHelp method, you must set the HelpFile and
    HelpCommand properties of the CommonDialog control to one of their
    appropriate constants or values. Otherwise, Winhlp32.exe doesn't display
    the Help file.
    CommonDialog1.ShowHelp
    HelpcontextID set to 0 for an option Button in a Frame, what will happen
    when press F1?
    A. Help conexts page is displayed
    B. HelpContextID property of form is evaluated
    C. HelpContextID property of the frame is evaluated *
    D. Context help for the Option Button control is displayed.
    Form’s HelpContextId is searched for non-zero value and if so, help is
    displayed for the Form
    If HelpContextID is set to 0, then Visual Basic looks in the HelpContextID
    of the object's container, and then that object's container, and so on.
    If a nonzero current context number can't be found, the F1 key is ignored.
    Debugging and Testing Issues
    •
    •
    Select appropriate compiler options.
    •
    •List and describe options for optimizing when compiling to native code.
    •List and describe the differences between compiling to p-code and
    compiling to native code.
    What code will have the most to gain on to be compiled to Native Code?
    A. Code that uses windows API
    B. Code that has much String functions
    C. Code that manipulates objects
    D. Code that have complex Financial calculations *
    Your application relies on arguments that are passed by reference. Which
    two native code compilation options should you select to optimize the
    performance of numeric processing?
    A. Assume no Aliasing
    B. Optimize for small code
    C. Remove VB floating point error checks *
    D. Remove Safe Pentium FDIV checks *
    You are creating an application that is intended to run on only PentiumPro
    based servers. You want to maximize the performance of this application.
    Which compiler option should you use?
    A. Assuming no Aliasing
    B. Optimize for small code
    C. Create symbolic debug information
    D. Remove safe for Pentium FDIV checks *
    You want the code written for debugging should not be compiled. How will
    you accomplish this?
    A. Use If .. Then .. Else Statements
    B. Use the Err Object
    C. Use conditional compilation *
    Which element can you use in a conditional compilation directive?
    A. Public variable
    B. Public constant
    C. Literal expression *
    D. Undefined constant
    Creating an application that uses conditional compilation to enable and
    disable elements of functionality, which two mechanisms can you use to set
    conditional compilation constants?
    A. Dim statement
    B. Constant statement
    C. #Constant directive *
    D. Project property dialog box *
    Q: Where do you define conditional compiling variables?
    A: Command line
    Project Properties dialog box (under the Make tab)
    In code
    Conditional compiling could be used to:
    1.designing an application to run on different platforms
    2.changing the date and currency display filters
    3.Remove debug code
    What expression is acceptable for #const Only literal and their operation
    except Is
    •
    •
    Set watch expressions during program execution.
    Q: When can you add watch variables?
    A: In Break and design mode
    Two advantages of using the context options in the Add watch dialog box are.
    A. Allow multiple projects scope
    B. Allow faster evaluation of expressions by narrowing content (of context) *
    C. Increase number of break mode options
    D. Viewing variables that have the same name but different scope *
    Sets the scope of variables watched in the expression. Use if you have
    variables of the same name with different scope. You can also restrict the
    scope of variables in watch expressions to a specific procedure or to a
    specific form or module, or you can have it apply to the entire application
    by selecting All Procedures and All Modules. Visual Basic can evaluate a
    variable in a narrow context more quickly.
    Monitor the values of expressions and variables by using the debugging
    windows.
    Which variable does the local window show? (select 2)
    A. All variables within a module
    B. All variables within your Application
    C. All variables within the Current procedure *
    D. All object variables within the current scope *
    Which task(s) can you perform by using the locals window
    A. Edit the call stack
    B. Define new variables
    C. View and change expressions
    D. View and change variables of the current procedure *
    Which three task can you perform by using the immediate window in break mode?
    A. declaring a variable as object
    B. declaring a function
    C. executing a function *
    D. executing the call stack
    E. view the value of the variable *
    F. changing the value of the variable *
    Immediate window: A control structure is valid only if it can be completely
    expressed on one line of code, use colons to separate the statements.
    You want to find out when a variable changes to a new value. Which tool would
    you use?
    - Watch window
    You are observing variable1 in Procedure1 in the Locals Window. Suddenly the
    Locals Window displays that the variable is "Out of Context" when it enters
    Procedure2. How was variable1 declared?
    A. As a Public in a standard Module
    B. As a Private variable in Procedure1 *
    C.As a Private variable in Procedure2
    D. As a Private variable in the General Section of the Form
    You want to test the Unload behavior of an In-Process component.
    What should you do?
    A. Start another instance of the development environment and create a test
    project that references the component.
    B. Create a project group that contains both a test project and the component
    *
    C. Add debug statements to the DLL component
    D. Call the free library function in the MS Windows API
    A control to be used by all programmers in a company. You need debug control:
    interaction with the same process as one of your applications. How to do?
    A. add control project to your app project *
    B. load control project in second instance
    C. in the app proj add a reference to control project
    D. in the control proj add a reference to app project
    •Q: What is the difference between debugging an ActiveX control project and
    an in-process component?
    A: The component code can run while the client is in Design mode
    •Q: When testing a UserControl, you add a standard.exe to your project group.
    UserControl in the Toolbox is dimmed. What should you do?
    A: Close the UserControl designer and then test again
    What should you do to debug an out of process component?
    A. Start a second instance of the development environment *
    B. Compile the component by using symbolic debug information
    C. Create an error handler for the out of process component
    D. Create a project group
    Define the scope of a watch variable.
    How to view contents of the Variant?
    A. Use Debug.print *
    B. Use Object browser
    C. Look at the Locals window *
    D. Copy to Clipboard
    Create a setup program that installs and registers ActiveX controls.
    Manage the Windows system registry.
    pplication-specific information in the registry. •Register components
    by using the Regsvr32.exe utility. •Register components by using the Remote
    Automation Connection Manager. •Edit the registry manually. •Register a
    component automatically.
    Save settings?
    A. local_Machine
    B. current_User *
    C. Current_Config
    D. Classes_Root
    IIS can not instantiate an object provided by the DLL (ActiveX) What should
    you do to the DLL?
    A. Digital Sign it
    B. Mark as safe for initialize
    C. Mark as safe for scripting
    D. Register by Regsvr32 utility *
    If you want to install your Visual Basic application in other computer, how
    do you find out about the components that are registered in that computer?
    REGSRV32.EXE
    Q: How to use Regsvr32.exe to install ActiveX DLL, EXE, OCX?
    A: To install ActiveX.dll - Regsvr32 dllname
    To install Activex.Exe - AX_exename /Regserver
    MSDN Deploying ActiveX Controls on the Web with the Internet Component
    Download
    DeSigning Controls for Use with HTML
    Which task can you accomplish by packaging in .cab file?
    A. creating license file
    B. digital sign it
    C. register on users computer *
    D. modifying users internet security settings
    Q: What cannot be done when an Internet Control is packaged. (Choose Two)
    A: Write to a file
    Read from the registry
    Q: How can you build ActiveX components for Internet distribution?
    A: Use the Application Setup Wizard and pick the appropriate options
    Q: What type of files does the Setup Wizard generates for Internet download
    setup? *.CAB files.
    ------------------------------------------------------------------------
    Q: Which function can the Setup Wizard of the Enterprise Edition of VB 5
    perform in addition to installing your ActiveX EXE project?
    A: install your project as an ActiveX shared component
    Q: What does locales show in different contexts?
    A: In Visual Basic, many functions use the user's system locale, which uses
    the Control Panel settings provided by the operating system to automatically
    determine the conventions at run time. These functions are called
    What is the event trigger sequence? Initialize, Load, Resize, Activate,
    Paint
    How to add the column to a ListView? MyListView.ColumnHeaders.Add ,,
    "MyNewCol"
    A unique feature of the Report view is ColumnHeader objects. The ListView
    control contains a collection of ColumnHeader objects in the ColumnHeaders
    collection.
    For which control does the ImageList control act as a central repository of
    images? ListImage
    An ImageList control contains a collection of ListImage objects, each of
    which can be referred to by its index or key.
    Set pnlX = StatusBar1.Panels.Add() ' Add a new Panel object.
    Set pnlX.Picture = ImageList1.ListImages(1).Picture ' Setting Picture must
    use set.
    What Property will you use to access BUTTONS of TOOLBAR? Key & Index
    StatusBar1.Style property allows the display of common data such as date,
    time, etc.
    Insert text to Statusbar SB1 Second panel- SB1.panels(2).text = "text"
    Your application has just deleted a record from a dynaset-type Recordset.
    What is the current record? The delete record.
    Which properties of the data control can be changed at run time? Recordset,
    databasename, recordsource
    The data in the currently selected row can be accessed using the Bookmark
    property, which provides access to the underlying Recordset object’s current
    record.
    Which type of recordset you will use to populate country names into a
    istBox? Forward-only
    Which recordset you will use to find a record in multi-user environment?
    Dynaset
    recordset.{FindFirst | FindLast | FindNext | FindPrevious} criteria .
    criteria likes the WHERE clause.
    Which two project types can contain an ActiveX Document? ActiveX Dll,
    ActiveX Exe.
    What project types can have ActiveX documents? - All that can be a container
    How to convert an ActiveX.DLL to multithread? - Make it ActiveX. EXE
    Advantages of Using ActiveX Documents - Support for the Hyperlink object and
    AsyncRead method
    Which project template would you select to build an in-process code
    (ActiveX Document DLL)?
    The AsyncRead method initiates an asynchronous download.
    Datatypes to be downloaded: files, pictures, byte arrays
    Which 2 actions may disqualify a component for being marked as safe for
    scripting? inserts in/reads from registry
    ID parameter in an HTML tag specifies the object name.
    When an error occurs in a component, call Err.Raise number.
    Err.Source returns the name of the object that generated an Error.
    Command1_Click() AND Command2_Click() call each other - Out of Stack Space
    error
    Before you use the CommonDialog.ShowHelp method, you must set the HelpFile
    and HelpCommand properties.
    If HelpContextID is set to 0, then Visual Basic looks in the HelpContextID
    of the object's container.
    Financial calculations will have the most to gain on to be compiled to
    Native Code.
    Optimize the numeric processing performance - Remove VB - Remove FDIV
    Literal expression can be used in a conditional compilation directive.
    How to set conditional compilation constants - #Constant directive,
    Project property dialog box
    When can you add watch variables? - In Break and design mode
    You can restrict the scope of variables in watch expressions to a specific
    context. Visual Basic can evaluate a variable in a narrow context more
    quickly.
    Locals window - View and change variables of the current procedure
    Immediate window - executing a function, view or change ariable
    Test behavior of an In-Process component - Create a project group
    Debug an out of process component - Start a second instance of IDE
    Save settings in – Hkey_current_User
    Find out about the components that are registered in that computer -
    REGSRV32.EXE
    To install ActiveX.dll - Regsvr32 dllname
    To install Activex.Exe - AX_exename /Regserver
    Which task can you accomplish by packaging in .cab file? register on users
    computer
    Q: There is a www server application that uses ActiveX controls you
    developed. When the application page is browsed with IE it does not show
    the ActiveX control. What may be happening?
    A1: No Internet download license file on the web server
    A2: Options in the Application Setup Wizard were not used correctly
    Q: Where do you define conditional compiling variables?
    Command line
    •Q: Difference between debugging an ActiveX control project and an
    in-process component
    Labels:

    vb questions 9

    Debug windows
    Immediate window
    •Automatically opens in Break-mode
    •To evaluate any executable statement
    •To find and change the value of variables and properties.
    •To Query or changethe value of a variable while running an application.
    Watch Window
    •Add Watch : In Break or Design Mode from the Debug Menu
    •You can watch the expression, breaking when the value of the watch
    expression is true or breaking when the value changes
    •It shows the current watch expression
    •The context column indicates the
    procedure module(s) in which each watch expression is Evaluated
    •You can edit a value
    Locals Window
    •Automatically displays all of the declared variables in the current
    procedure scope and their values.
    Calls Stack lists all active procedure calls in the Application that where
    started but not completed. You can only display the Call stack window when
    the application is in break mode.
    q: You have two text boxes Text1 and Text2. the Tab index of text1 is set to
    0. what will happen when u set the tab index of text2 to 0?
    A: Tab index of text1 is set to 1
    Which code fragment is proper use of the Forms collections?
    A. Dim form1 As Form *
    For each form1 in Forms
    MsgBox form1.Caption
    Next Form1
    B. Dim form1 As Form
    For each form1 in Forms
    MsgBox Forms.Item(form1).caption
    Next Form1
    C. Dim form1 As Form
    For each form1 in forms
    Msgbox form1.remove
    Next Form1
    D. Dim form1 As Form
    For each form1 in Forms
    Msgbox form1.add()
    Next Form1
    Which property is only valid for a collection object?
    A. UBOUND
    B. LBOUND
    C. Count *
    D. Index
    What are the benefits of Forms collection?
    - Allows faster unloading of all forms in the project *
    - Faster access
    - Standardized mechanism for tracking multiple instances of a form *
    - Group forms & drag the group
    Default firing order of events of a form?
    A. Load, Initialize, Resize, Paint
    B. Load, Initialize, Paint, Resize
    C. Initialize, Load, Resize, Paint *
    D. Initialize, Load, Paint, Resize
    Start from Main, contain form1, Form1.caption = "blah". Which events will be triggered?
    A. load
    B. initialize
    C. initialize, load *
    D. initialize, load, activate
    •How do you dynamically load controls : Load object_name
    Q: What is the sequence in which the events in the form will trigger
    A: Initialize, Load, Resize, Activate, Paint
    Dim x As Integer
    What event gets fired? Initialize
    -----------------------------------------------------------------------
    Which control can you place directly on an MDI-Form?
    - Image
    – Richtext Box
    – Picture Box *
    - Hscrollbar
    - Option Control
    - Frame
    The PictureBox, Data controls, Timer controls and Menu controls are the only
    standard Visual Basic controls that you can place in the internal area of an
    MDI form.
    Form1 contains a command button control that has code in one of its events.
    To cut the control from form1 and than paste the control onto form2.
    Where is the event located?
    A. It is in the same event of the command button control of form2
    B. It is in a different event of the command button control on form2
    C. It is deleted when the command button control is cut from form1
    D. It is in the General object procedures of form1 *
    ProgressBar with visible property set true. To display progress of a lengthy
    operation in you application. Which property will you set?
    A. value *
    B. width
    C. max
    D. index
    DragOver Form1 to change color of label1
    A. Target.color = true
    B. Source.color = true *
    C. DragLabel.color = true
    D. DragControl.color = true
    Form1 allow dragging Label1. Which line code use in DragOver event of Form1
    to change bg color of Label1 to red?
    A. Target.BC = vbRed
    B. Source= vbRed *
    C. DragLabel= vbRed
    D. DragControl= vbRed
    Which OleDragOver event parameter indicates dragging onto or away from a
    target object?
    A. effect
    B. state *
    C. index
    D. data
    Copy picture from picturebox control to other app which prop use?
    A. oledropMode of the picturebox control
    B. oledropMode of the form containing pictureBox control
    C. oledragMode of the picturebox control *
    D. oledragMode of the form containing pictureBox control
    You want to trap a function key in a textbox. - Use the Keydown event.
    A textbox to allow only numeric entries. - Use the Keypress event.
    Form1 and Form2 place code in the Terminate event of Form1. Which code to
    add in order to cause the Terminate event of Form1 to occur from Form2?
    A. F1.Click unload F1
    B. F1.hide F1.close
    C. unload F1 set F1=nothing *
    D. unload F1 end
    You have a Label1 on an UserControl1, what event for Label1 to be stretched
    during design time?
    A. UserControl_Initialize
    B. UserControl_Resize
    C. Label1_Initialize
    D. Label1_Resize *
    Q: You have a Label Control in USERCONTROL. If the user resizes the
    usercontrol during run-time, in which event will u handle the resizing of the
    label (so as to view the Label control)?
    A: USERCONTROL_RESIZE
    How do you find out if F2 is being pressed?
    A. Click
    B. Validate
    C. KeyDown *
    D. KeyPressed
    Your form contains a command button control named Command1. The index
    property of command1 is set to 0. You want to load a second instance of the
    command button that has its index property set to
    1. Which line should you use?
    A. load command1.1
    B. load command1(1) *
    C. load command1.index = 1
    D. load command1.index (1)
    Combine menu controls of object1 with the existing menu on form1
    A. form1.NegotiateMenu = true *
    B. form1.NegotiatePosition = true
    C. object1.NegotiateMenu = true
    D. object1.NegotiatePosition = true
    Using the NegotiateMenus property, you determine if the menu bar of a form
    will share (or negotiate) space with the menus of an active object on the
    form.If you uncheck the Visible property for a menu item, the menu items
    below will move up to fill the empty space.
    How to attribute Access Keys to menus? &Save
    What can you do with a dynamic menu?
    A. You can add function keys to it
    B. You can add pop-up menus to it *
    C. You can deleted it after creating it *
    D. You can create it from the Menu Editor
    How to allow menu items to be added at runtime?
    A. redimension the menu control array
    B. use the add method *//dynamic menu
    C. use the load statement
    D. set up the menu with blank spaces initially and change at runtime
    Q: How will you allow users to edit your control at design time?
    A: Set the EditAtDesignTime property of your UserControl object to True.
    Q: How do you make your UserControl Object Invisible at run-time?
    A: Set the InvisibleAtRuntime property of the UserControl object to True.
    Menu control: Which property can only be changed during design time?
    - visible
    - caption
    - checked
    - shortcut *
    How to refer to the contents of the child of the selected node of a TreeView?
    Set nodChild = TreeView1.Nodes(TreeView1.SelectedItem.Index).Child
    •tvwMyTree.Nodes(10).Children ‘ return the number of children
    tvwMyTree.Nodes(10).Parent.Text ‘ return the Text of Parent
    Display Icon for each item in the hierarchy of the website?
    A. Outline
    B. Listbox
    C. Listview
    D. Treeview *
    A TreeView control displays a hierarchical list of Node objects, each of
    which consists of a label and an optional bitmap. A TreeView is typically
    used to display the headings in a document, the entries in an index, the
    files and directories on a disk, or any other kind of information that might
    usefully be displayed as a hierarchy.
    You are writing code for a Drag and Drop operation. You want to set the
    DropHighLight property to highlight the target TreeView control element?
    A. HitTest *
    B. Drag
    C. TextHeight
    D. StartlabelEdit
    The DropHighlight property is typically used in combination with the HitTest
    method in drag-and-drop operations for TreeView and ListView Controls.
    You use the add method of the TreeView control, which parameter can you use
    to control the creation of a child node?
    A. Key
    B. Text
    C. Relative *
    D. Relationship
    How to add the column to a ListView?
    MyListView.ColumnHeaders.Add ,, "MyNewCol"
    A unique feature of the Report view is ColumnHeader objects.
    The ListView control contains a collection of ColumnHeader objects in the
    ColumnHeaders collection.
    What properties can you set while using the Add property for a list view?
    •ColumnHeader object.Add(index, key, text, width, alignment, icon)
    •Provide controls with images by using the ImageList control.
    For which control does the ImageList control act as a central repository of
    images? ListImage
    An ImageList control contains a collection of ListImage objects, each of
    Which can be referred to by its index or key.
    Dim pnlX As Panel
    Set pnlX = StatusBar1.Panels.Add() ' Add a new Panel object.
    Set pnlX.Picture = ImageList1.ListImages(1).Picture ' Setting Picture must
    use set.
    TreeView1.ImageList = ImageList1 ' Specify ImageList
    TreeView1.Nodes(3).Image = 1 ' Use Index property of ImageList1.
    TreeView1.Nodes(3).Image = "image 1" ' or Use the Key property "image 1."
    What Property will you use to access BUTTONS of TOOLBAR?
    Key & Index
    Which StatusBar property allows the display of common data such as date, time
    etc?
    A. Text
    B. Style *
    C. Object
    D. SimpleText
    Statusbar SB1 Second panel set key property to panel2
    Which display the message "blah" in second panel
    A. SB1.(2)Text = ..
    B. SB1.panels(2).text = .. *
    C. SB1.Panels.(panel2).text = ..
    D. SB1.PanelItems("panel2").text = ..
    If you intend to add a user control or any ActiveX control to your form,
    you must either add the control to the Toolbox, or add its License key to
    the Licenses collection.
    •Option Explicit
    Private WithEvents extCtl As VBControlExtender
    Private Sub Form_Load()
    Licenses.Add "project1.WeeksCtl", "xydsfasfjewfe"
    Set extCtl = Form1.Controls.Add("project1.WeeksCtl", "ctl1")
    extCtl.Visible = True ' The control is invisible by default.
    End Sub
    Q: When should you use public variables instead of property procedures for
    read-write properties?
    A: The property is a String data type, and there is no constrain on the size
    or value of the string.
    Correctly use of ParamArray keyword?
    - At the end of the (……. As….. , ……As ……, Param Array )
    - And not in combination with the Optional keyword
    You have a variable x. You use the Watch window to see the contents of x. At one time the value of x=100 and the next step is says. It has occurred when the 1 process was finished and the second process was started. How was x declared?
    A. Local to 1st procedure *
    B. Local to 2end procedure
    C. Public in a procedure
    D. Public in the General declaration section of the form
    Procedure in class module visible to the project not to other application
    A. private function Report1 as bool
    B. private function Report1() as bool
    C. public function Report1() as bool
    D. friend function Report1() as bool *
    A variable is declared as Public in a form. From where can the Variable be
    referenced?
    A. Only from other procedures in the same form.
    B. Only from forms in the same project
    C. From anywhere in the same project *
    D. From modules in other project
    Which elements are supported in the definition of property procedures
    - optional argument *
    - address of operator
    - alias keyword
    - paramArray keyword *
    You want a procedure to be visible only to objects in the current project.
    You want that this procedure should be accessible by external clients.
    How will you declare the Procedure?
    A. Private
    B. Friend
    C. Public
    D. Static
    How can you create a read-only property Private and a write-only property
    Public. Which of the following are true?
    •A. Private Property Get Name() As String *
    Name = txtname.text
    End Property
    Public Property Let Name(ByVal NewName as String)
    TxtName.text = NewName
    PropertyChanged "Name"
    End Property
    B. Public Property Set Name() As String
    •Name = txtname.text
    End Property
    Private Property Let Name(ByVal NewName as String)
    TxtName.text = NewName
    PropertyChanged "Name"
    End Property
    C. Public Property Let Name() As String
    Name = txtname.text
    End Property
    Public Property Set Name(ByVal NewName as String)
    TxtName.text = NewName
    PropertyChanged "Name"
    End Property
    You have to indicate the property changes for an object.
    Which of the following is best suited for the above scenario?
    A. Property Get
    B. property Let
    C. Public Sub() *
    D. Public Function()
    How can you create a read-only property for a class?
    A. Define a Property Get procedure and define a Property Let procedure with
    no arguments.
    B. Define a Property Get procedure and a Property Let procedure.
    C. Define a Property Get procedure without a Property Set or Property Let
    procedure. *
    D. Define a Property Set or Property Let procedure without a Property Get
    procedure.
    How can you create a read-only property?
    A. Omit the Property Let procedure *
    B. Omit the Property Set procedure
    C. Set its ReadOnly property to true
    D. Use the Private keyword when declaring the procedure
    What are the two restrictions on how the Implements statement can be used?
    A. It requires a reference to a type Library *
    B. It can be used only once in an application
    C. It cannot be used in standard module *
    D. It cannot be placed in the general declaration section of a module
    Q: What is the purpose of the Implements keyword?
    •A: The Implements keyword is used to create a secondary interface.
    For instance, if your application has a reference to a type library that
    describes the IGrowth interface, you could create a secondary interface in a
    class module using "Implements IGrowth".
    You want to create an instance of an ActiveX component that can Asynchronously
    signal projects that use it. What should you create? (Choose two)
    A. an event
    B. an object callback *
    C. the Addressof Operator *
    D. the Implements statement
    Which type of Instancing should you use for the class module?
    A. private
    B. multiUse
    C. GlobalMultiUse *
    D. PublicNotCreatable
    Sink the events of class1. How define a variable MyVar
    A. Dim MyVar as object
    B. Dim MyVar as Variant
    C. Dim MyVar as new Class1
    D. Dim WithEvents my as class1 *
    Q: Where and why to use Friend methods and properties
    A: The combination of public to classes in the same project and private to
    the external.
    You have a Data Control with Bound Controls.
    You want to provide the ability to abort changes in the record currently
    being edited and to refresh the bound controls. How?
    Only invoke the UpdateControls method for the Data control.
    UpdateRecord Updates database (recordset) with data from bound controls.
    UpdateControls Updates database (recordset) changes to bound controls.
    Refresh Creates a new recordset based on data control properties.
    Update Update recordset with data from bound controls or through code.
    Your application has just deleted a record from a dynaset-type Recordset.
    What is the current record? The delete record.
    Which properties of the data control can be changed at run time?
    Recordset, databasename, recordsource
    •Q: A list-box is used as a constituent control. The design window is closed
    and the control inserted on a form in another project. The user then sets the
    sort property of the control which in turn sets the sort property of the
    control. Why does the error occur?
    A: Compile the control project ?
    U have Form,a FRAME & ListBox inside frame. If u set SORT property of Listbox
    at design time, what will happen.
    •box.List(index)
    box.RemoveItem index
    box.AddItem item[, index]
    DBGrid is a collection of Column objects.
    the DBGrid control depends on two other objects:
    •The Recordset object of the data control
    •The Columns collection of the DBGrid itself
    Each cell of a DBGrid control can hold text values, but not linked or
    embedded objects.
    •Add a data control to a new form, and set its DatabaseName and RecordSource
    properties to the database and table you want to display.
    •Add a DBGrid control to the form, and set its DataSource property to the
    data control you just created. The DBGrid column headers set automatically
    from a Data control's Recordset object.
    Q: How to set properties for the individual Column objects?
    A: You must make the DBGrid control UI-active: Select the right mouse button,
    and choose Edit. Then use pop-up menu.
    Q: How to remove column header?
    A: object.ColumnHeaders = False
    Q: How to refer a colmun?
    A: object.ColIndex [= value]
    This property returns the zero-based index of a column within the Columns
    collection.
    Q: How to check the value of a specific field in the current record?
    A: MyString = Data1.Recordset.Fields("Title").Value
    The data in the currently selected row can be accessed using the Bookmark
    property, which provides access to the underlying Recordset object’s current
    record.
    You have 2 tables based upon which reports are to be generated by making use
    of a common Field. The existing Table structure and Report definitions should
    not be changed. Which of the following is most appropriate.
    A. create a new table and use Filter
    B. Create a new table and use Sort
    C. create a new Dynaset using Filter*
    Which type of recordset you will use to populate country names into a
    ListBox? Forward-only Which recordset you will use to find a record in
    multi-user environment? Dynaset
    To locate specific records you can use the Find methods with dynaset- and
    snapshot-type Recordset objects, and the Seek method with table-type
    The Seek method works only with table type recordsets, because Visual Basic
    uses the table’s current index
    •table.Seek comparison, key1, key2 ...
    Labels:

    vb questions 8

    Class Module

    Property procedures
    Property Get - Returns the value of a property.
    Property Let - Sets the value of a property. – Let x = 3
    Property Set - Sets the value of an object property. – Set objThing = New
    Thing
    •Property procedures are public by default. •The Property Get declaration
    must use arguments with the same name and data type and less one number as
    the arguments in the Property Let procedure. •The data type of the
    final argument in a Property Set declaration must be either an object type or
    a Variant.


    ••To create a read-only property, simply omit the Property Let or (for object

    properties) the Property Set.


    Event


    An object that raises events is called an event source. To handle the events
    raised by an event source, you can declare a variable of the object's class
    using the WithEvents keyword. WithEvents variables must be module-level
    variables.
    •
    •Option Explicit

    Private WithEvents mWidget As Widget







    Limitations on WithEvents Variables
    ••A WithEvents variable cannot be a generic object variable. That is, you
    cannot declare it As Object.

    •You cannot declare a WithEvents variable As New. •You cannot declare
    WithEvents variables in a standard module. •You cannot create arrays of
    WithEvents variables.




    Inside Class module, use Public Event … RaiseEvent… pair. Events are always
    Public.








    DragOver event determines what happens after dragging is initiated and before
    a control drops onto a target. This event occurs only if OLEDropMode is set
    to 1 (Manual).



    Private Sub Form_DragOver(source As Control, x As Single, y As Single, _

    state As Integer)



    Source - The control being dragged.

    State - The transition state of the control being dragged in relation to a
    target form or control. 0: enter, 1: leave, 2: over.



    Private Sub object_OLEDragOver(data As DataObject, effect As Long, button _

    As Integer, shift As Integer, x As Single, y As Single, state As Integer)



    Moving DataObject (not Control) from one control or application to another.








    KeyDown and KeyUp events occur when the user presses (KeyDown) or releases
    (KeyUp) a key while an object has the focus. (To interpret ANSI characters,
    use the KeyPress event.)







    Polymorphism



    VB supports Interface inheritance by two steps:





    1.
    1.2.Define interfaces – a class module by adding methods without code.
    3.Define Child class using keyword Implements, then implement all the
    properties and methods of parent interface.



    Option Explicit



    Implements Animal



    Private Sub Animal_Move(ByVal Distance As Double)

    Debug.Print "Flea moved"

    End Sub



    VB doesn’t support aggregation.







    Component Programming








    To declare an object variable for an object not defined in a type library





    Dim objAny As Object








    The main difference between declaring a variable of a specific class and
    declaring a variable of the generic Object class is in how ActiveX binds
    the variable to the object. When you declare a variable of the generic
    Object class, ActiveX must use late binding. When you declare an object
    variable of a specific class, ActiveX uses early binding, which can speed
    object references.





    Assigning an Object reference








    If the ActiveX component supplies a type library, using NEW

    If not, using



    Set objectvariable = CreateObject("progID", ["servername"])

    Or Set objectvariable = GetObject([pathname] [, progID])



    For example:

    Dim xlApp As Object

    Set xlApp = CreateObject("Excel.Application") ‘late binding






    Dim wdApp As Word.Application

    Set wdApp = GetObject("", "Word.Application")





    Set X = GetObject(, "MySrvr.Application")








    X references an existing Application object.



    Dependent objects are lower in an object hierarchy, and they can be accessed
    only by using a method of an externally creatable object. Defined by Class
    Instancing property - PublicNotCreatable.



    Data associated with an embedded object is not persistent; that is, when a
    form containing an OLE container control is closed, any changes to the data
    associated with that control are lost. To save updated data from an object to
    a file, you use the OLE container control's SaveToFile method.





    Private Sub cmdSaveObject_Click ()

    Dim FileNum as Integer ' Get file number.

    FileNum = FreeFile ' Open file to be saved.

    Open "TEST.OLE" For Binary As #FileNum ' Save the file.

    oleObj1.SaveToFile FileNum ' Close the file.

    Close #FileNum

    End Sub








    If the object is linked, then only the link information and an image of the
    data is saved to the specified file. The object's data is maintained by the
    application that created the object. If a user wants to save changes to a
    linked file, the user must choose the Save command from the ActiveX
    component's File menu because the SaveToFile method applies only to
    embedded objects.







    Asynchronous notifications and implementation








    A client makes a method call and tells the component it wants to be
    notified when certain things happen. Then the client can be free to do
    other things while it’s waiting for component notification. Two
    implementations: An event is like an anonymous broadcast, while a call-back
    is like a handshake 4.Using events – RaiseEvent - WithEvents



    Using Call-back

    Test ActiveX Component








    To test a component, you need to create a client application.
    If you’re creating components as part of an application, you can use the
    application itself as the test program. The test project must be an Exe
    project. To test call-backs, use an ActiveX Exe project.



    To test In-process server:

    5.Create a Project Group containing the component and test project. 6.Set
    test project as active project and make a reference to the component. ( not
    necessary for ActiveX control)

    7.Add code to test the properties and methods of each public class provided
    by your component.





    To test Out-of-process server:
    ••Make Component executable. •Ctrl+F5 to run component
    project. You cannot add a reference to the component project unless it’s in
    run mode.

    •Open a second instance of the Visual Basic development environment.
    •Start a new test project and make a reference to the component. •Add code
    to test the properties and methods of each public class provided by your
    component.






    The difference between debugging controls and debugging other objects is
    that some of the code in your control must execute while the testing form is
    in design mode. To put a control into a state such that its code can execute
    at design time, you must close the control's visual designer to enable the
    control's icon in the Toolbox.

     



    Software Distribution



    Three ways to start the Package and Deployment Wizard:
    1.
    1.
    1.In your application project, start from Add-In 2.Run it as a stand-alone
    component from outside IDE. 3.Start it in silent mode by launching it from a
    command prompt. Unattended with script.



    •PDCmdLn.exe C:\Project1\Project1.vbp /p "Internet Package" /d Deployment1

    /l "C:\Project1\SilentMode.log"






    Signing and licensing must be done outside of the packaging process.

    A dependency (.dep) file contains information about the run-time requirements
    of an application or component. In Visual Basic, dependency information is
    stored in files generated by the Package and Deployment Wizard or created
    manually by you.
    •Component Dependency File: A .dep file lists all the files required by a
    particular component. When you purchase or use a component from a vendor,
    you receive a .dep file from them. •The VB6dep.ini file provides the Package and Deployment Wizard with an all-purpose list of dependencies and references used by Visual Basic. This list is created when you install Visual Basic and resides in the \Wizards\PDWizard subdirectory of the main Visual Basic directory.


    For a standard package, the information from the .dep files is written to a
    Setup.lst file that is stored outside the packaged .cab file. For an
    Internet package, the .dep file information is written to an .inf file that
    is stored within the packaged .cab file.

    The Setup Toolkit is a project installed with Visual Basic that is used by
    the Package and Deployment Wizard when it creates a setup program,
    setup1.exe. By default, the Setup Toolkit uses the \Program Files
    directory as the root location. When installing a file on the
    user's machine, you should not copy an older version of the file over a new
    version.

    The Setup.lst file describes all the files that must be installed on the
    user's machine for your application and contains crucial information for the
    setup process.



    Internet Distribution



    The Setup Wizard will create a .cab file, known as the primary .cab file,
    which contains:
    •The project components, such as the ActiveX control, ActiveX DLL, or
    ActiveX EXE •The .inf file, which contains links to other .cab files that
    contain Visual Basic support files and controls, as well as other
    information, such as whether the control is safe for scripting and safe for
    initialization and registry information as defined by the user. This file
    replaces the Setup.lst file that the Setup Wizard creates in the standard
    setup. •Reserved space for digital signatures. •All files that are not in
    other (secondary) .cab files. Secondary .Cab Files: For ActiveX control
    projects, ActiveX EXEs, and ActiveX DLLs, all run-time components such as
    Msvbvm50.dll, individual controls, Data Access Objects (DAO), and Remote
    Data Objects (RDO) are packaged into separate .cab files, digitally signed
    by Microsoft, and placed on the Microsoft Web site. You can choose to link
    your files to the .cab files on the Microsoft Web site, or you can download
    local copies of them.


    When you compile a ActiveX control with licensing support. The .VBL file
    will contain licensing info(use the "Requiere License"Key option, located
    in the General tab of the Project Properties dialog box.)

    Only an ActiveX control can be used with the Create Download Setup option
    in the Setup Wizard.

    ActiveX documents use the NavigateTo method to get to URL Adresses on WWW.
    The ActiveX document must be in a hyperling-aware containter and in a
    container that maintains a history of documents to use the "goBack"
    and "goForward" methods to move between previously visited documents.



    Advantages of Using ActiveX Documents:
    ••Support for the Hyperlink object •Support for the AsyncRead method


    The benefit of using secondary .cab files from a Web site are:

    You do not need to distribute all of the .cab files required by your
    application. The only file you need to distribute is the primary .cab file.
    The .inf file within the primary .cab file points to the Microsoft Web site
    and downloads the necessary .cab files based on the needs of the end user.
    They provide an efficient means of delivering updates to your product.
    If you cannot or do not want your application setup to require a connection
    to the Internet, you may place the secondary .cab files on a ser<

      •Create a file with a name supplied by a script. •Read a file from the
      user's hard drive with a name supplied by a script. •Insert information
      into the Windows Registry (or into an .ini file), using a key (or filename)
      supplied by a script. •Retrieve information from the Windows Registry

      (or from an .ini file), using a key (or filename) supplied by a script. •
      Execute a Windows API function using information supplied by a
      script. •Create or manipulate external objects using programmatic IDs
      (for example, "Excel.Application") that the script supplies.


      A safe for initialization control does not write or modify any registry
      entries, .ini files, or data files as a result of initialization parameters.

      The downloaded license key is not added to the registry. Instead, browser
      asks the control to create a run-time instance of itself, and passes it the
      downloaded license key.

      Only the DBGrid control requires a license key on a Web server.

      There is a fine line between a safe and unsafe action. For example,
      a control that always writes information to its own registry entry may be
      safe. A control that allows you to name the registry entry is unsafe.
      A control that creates a temporary file with a name it creates without using
      any initialization or scripting value may be safe. A control that allows the
      name of the temporary file to be assigned at initialization or by scripting
      is unsafe.

      A control marked safe for initialization guarantees to do nothing bad no
      matter what data it is initialized with The critical issue is what may
      happen as a result on initialization with particular values. A control that
      automatically sends information at initialization to an HTTP server may be
      safe, as long as the server address cannot be changed. You may create files
      and any other activities needed for the control as long as the file
      properties (name, file size) or activity’s nature does not change becau

      MSDN, "Deploying ActiveX Controls on the Web with the Internet Component
      Download"
    Labels:

    vb questions 7

    1) If your user wants to uninstall the application you developed, which
    method will you use to make it easy for him
    a) Use setup wizard (*)
    b) Customize the Setup.exe
    2) If you have a progress bar. what propertry would you use to show its
    status.
    a) Index
    b) Value(*)
    3) What error do you get if the following code is executed
    Private Command1_Click()
    Command2.Value = TRUE
    End sub
    Private Command2_Click()
    Command1.Value = TRUE
    End sub
    Ans : Stack Overflow error
    4) How do you create a Public read only and Private Read/Write. The options
    were something like
    a) Public Get Name()
    Name = stname
    End
    Private Let Name( stname as string)
    stname = Name
    End
    b) Public Get Name()
    Public Let Name()
    c) Private Get Name()
    Private Set Name()
    d) Public Get Name()
    Private Set Name()
    5) When a user browses a web page which has a control you developed and the
    browser displays a warning. what will you ask your user to do.
    Ans : Ask the user to set his browsers security level to none or zero.
    6) What event would you use if a user presses F2
    7) A ListBox is in a frame. The HelpContextId of the ListBox is set to 0.
    When the user presses F1 and the ListBox has focus What happens.
    8) If you have a number of controls to distribute over the Web. How would you
    decrease the download time for the user.
    9) When the following code executes. What will the user see
    Public Sub MyTest()
    On Error GoTo ErrHandler
    Dim X as Integer
    MyProc(X)
    MsgBox "XXX"
    Errhandler:
    MsgBox "YYY"
    End Sub
    Public Sub MyProc()
    On Error GoTo MyprocErr
    X = X / 0
    MyprocErr:
    MsgBox "ZZZ"
    End Sub
    a) "XXX" Only
    b) "ZZZ" Only
    c) "XXX", "ZZZ" and "YYY" Only
    d) "XXX" and "ZZZ" Only
    10) When you are testing your user control. you add a standard exe to your
    project group. But the user control in your tool bar is dommed. What should
    you do?
    11) Which code would you use to create a instance of Form1
    a) Dim Frmx as Form1
    b) Dim Frmx as New Form1
    c) Dim Form1 as Form
    d) Set Frmx = GetObject("Project1.Form1")
    12) How would you display text in a status bar which has its 2nd panel key
    as"Panel2"
    a) Statusbar1.Panel2.Text = "Printing ..."
    b) Statusbar1.Panel(2).Text = "Printing ..."
    c) StatusBar1.Panel("Panel2") = "Printing ..."
    1 . Use Regsvr32.exe to install Active X DLL, EXE, OCX.
    To install ActiveX.dll: Regsvr32 dllname
    To install Activex.Exe: AX_exename /Regserver
    ------------------------------------------------------------------------
    2 Test Activex.EXE (out-of-process) component
    2 instances of VB
    Test Activex.DLL (in-process) component
    Add Standard.EXE and use 1 instance of VB
    Debug ActiveX control project
    Run Active x control while the client is in design mode
    ------------------------------------------------------------------------
    1)When testing a User Control, you add a standard.exe to your project group.
    User control in the Toolbox is dimmed. What should you do? Close the User
    Control designer and then test again.
    ------------------------------------------------------------------------
    4 Advantages of using Watch window:
    -----------------------------------------------------------------------
    5 What can be viewed in the local window?
    All the variables in the procedure scope
    ------------------------------------------------------------------------
    6 Immediate Window:
    view, add, change and declare variables and see the result being returned.
    ------------------------------------------------------------------------
    7 What Call stack shows?
    ------------------------------------------------------------------------
    8 Why the context property in Immediate window is useful?
    -----------------------------------------------------------------------
    9 Autoredraw = False only affects line, pset, cicle created at run-time, not
    design time. Use Refresh instead of Autoredraw to save system resources.
    ------------------------------------------------------------------------
    10 DropHighlight used for drag-and-drop operation on a TreeView and
    DropHightlight goes with HitTest in an OLE dragDrop operation
    ------------------------------------------------------------------------
    11 ActiveXDocument.Hyperlink.Helpfile
    Use Hyperlink object on ActiveX Document, needs a hyperlink-aware container,
    e.g. IE4
    ------------------------------------------------------------------------
    12 Property procedures e.g. Public Property Get ABC (ByVal... ByRef...
    Optional...ParamArry intNum) Those in parantgese are optional argument types.
    ------------------------------------------------------------------------
    13 How to declare DLL functions:
    ------------------------------------------------------------------------
    14 AsynRead method is used to do asynchronous download. Datatypes to be
    downloaded: files, pictures, byte arrays
    ------------------------------------------------------------------------
    15 Implements as keyword used in a class module - used for Automation
    Implements ABCDE
    'ABCDE is a secondary interface created based on the type library's abstract
    interface. How to do it? Set reference to the type library
    What should be the syntax using Implements keyword?
    -----------------------------------------------------------------------
    16 Disadvantage of using Implements keyword:
    Can only be used in Standard module;
    Need to declare all the public variables, etc.
    ------------------------------------------------------------------------
    17 LockEdits = False
    Optimistic locking, the record (2k page) be locked when you use the method
    update
    LockEdits = True
    Pessimistic locking, the record (2k page) will be locked when you use the
    method Edit
    Get familiar with different situations using LockEdits and understand it.
    ------------------------------------------------------------------------
    18 Create private property - read only
    Private Property Get ABC (no Property Let nor Property Set)
    Create public property - write only
    Public Property Let
    PropertyChanged "BBB"
    ------------------------------------------------------------------------
    19 What can be placed on MDI form?
    Picturebox control (not image control)
    timer control, Data control, Menu control
    ------------------------------------------------------------------------
    20 Public variable declared in a form
    Scope : entire application, make reference to form name if necessary
    ------------------------------------------------------------------------
    21 Data control's default Recordset type: dynaset-type recordset
    ------------------------------------------------------------------------
    22 HelpContextId = 0 is the default. If the HelpContextId of a botton control is set to zero, the container, i.e. frame or form's HelpContextId will be used. If there are no HelpContextID specified in the container, then NO HELP.
    ------------------------------------------------------------------------
    23 CommonDialog1.ShowHelp
    This requires : CommonDialog1.HelpFile to be set
    CommonDialog1.HelpCommand to be set
    maybe a reference to CommonDialog1.HelpKey
    ------------------------------------------------------------------------
    24 Change the BackColor of UserControl's label1
    Use Ambient Properties
    ------------------------------------------------------------------------
    25 In a DragOver event, how to change the backcolor of the label which is
    being dragged over the target?
    Source.BackColor = vbRed
    ------------------------------------------------------------------------
    26 Active X files for internet distribution:
    Inf file equivalent to Setup.lst file
    Inf file contains references to files, support files
    .cab file (contains ActiveX.dll or .exe, inf file that is equ. to Setup.lst
    file with links to support files, sec. cab files, space for digital signing)
    .vbd file
    .htm file
    ------------------------------------------------------------------------
    27 How to reduce the time for downloading on Internet an Active X componet?
    Create separate secondary .cab files.
    Users may already have these secondary .cab files on the system or the
    secondary .cab files can be downloaded from Microsoft's web site.
    ------------------------------------------------------------------------
    28 StatusBar panels - is 1-based?
    Get familiar with how to show a string in, for instance, the 2nd panel of a
    statusbar.
    ------------------------------------------------------------------------
    29 Toolbar
    Properties: Button.Key and Button.Index
    ------------------------------------------------------------------------
    30 What event will be fired when you move from one record to another in a
    recordset?
    Update
    ------------------------------------------------------------------------
    31 How to Pass Null to DLL
    ByVal as String
    pass vbNullString
    ------------------------------------------------------------------------
    32 Conditional Compilation
    Can use literal statements except the IS operator
    ------------------------------------------------------------------------
    33 Where do you define conditional compiling variables?
    Command line
    Project Properties dialog box (under the Make tab)
    In code
    ------------------------------------------------------------------------
    34 Dim x As Integer
    What event gets fired? Initialize
    -----------------------------------------------------------------------
    35 How to convert an ActiveX.DLL to multithread?
    Make it ActiveX. EXE
    ------------------------------------------------------------------------
    36 How to raise an event"
    first to declare it, use the Event keyword, then Raise it. e.g. RaiseEvent
    ABC (arguments)
    ------------------------------------------------------------------------
    37 How to add a control to a web page? By scripting
    ------------------------------------------------------------------------
    38 Press F2, what event is fired? KeyDown
    ------------------------------------------------------------------------
    39 What property of ProgressBar to show status? Value
    ------------------------------------------------------------------------
    40 Under what situation will you have this error message "Out of Stack
    space"?
    ------------------------------------------------------------------------
    41 With TreeView control, use Add method to add a child node.
    It goes with "Relationship" not "Relative", know the keyword tvwFirst,
    vwLast, etc.


    ------------------------------------------------------------------------


    42 Hyperlink object, GoForward and GoBack

    Webrowser, GoHome and GoSearch


    ------------------------------------------------------------------------


    43 How to pass Null pointer to a C function that is expecting a character
    type?

    VB byte type?


    ------------------------------------------------------------------------


    44 GlobalMultiuse

    For ActiveX.DLL and ActiveX.EXE

    Enable you to use the properties as if the component is an intrinsic
    controls, there's no need to declare the variables, one instance of the
    class created for multiple client use.


    ------------------------------------------------------------------------


    45 DBGrid's column property is 0-based


    ------------------------------------------------------------------------


    46 Dynaset and filter property


    ------------------------------------------------------------------------


    47 Setup a standard.exe, VB5DEP.INI is the dependency file


    ------------------------------------------------------------------------


    48 An error occurs in a component that you wrote, how to notify client:

    Err.Raise number


    ------------------------------------------------------------------------


    49 How to create a license package for ActiveX control licensing

    Use LPK_Tool.exe


    ------------------------------------------------------------------------


    50 How to dynamically create or remove controls?

    Set up control arrays at design time, at run time, use Load and Unload
    control statements.

    e.g. Load ABC(index#)

    e.g. Load mnuFile(2) for dynamic menu


    ------------------------------------------------------------------------


    51 When can you add watch statements?

    At design time or break mode.


    ------------------------------------------------------------------------


    52 What property to set if you want both menus (from the object and from the
    container) shown ?

    NegotiageMenus on the container


    ------------------------------------------------------------------------


    53 How do you implement a sink event of a class using a variable?




    Visual Basic 6.0 Study Guide



     



    Program Structure



    A typical application consists of one or more modules: a form module for
    each form in the application, optional standard modules for shared code,
    and optional class modules. Each module contains one or more procedures that
    contain the code: event procedures, Sub or Function procedures, and Property
    procedures.

    Startup Form can be set in Project Properties. Sub Main() can only be in a
    standard module. To display a splash screen, use a Sub Main procedure as
    startup object and use the Show method to display the form:





    Private Sub Main()

    frmSplash.Show ' Show the splash screen.

    … ' Add startup procedures here.

    frmMain.Show ' Show the main form and unload the splash screen.

    Unload frmSplash

    End Sub








    Three ways to end an application:
    Single Form

    Multiple Forms



    Private Sub cmdQuit_Click ()

    Unload Me

    End Sub




    Private Sub Form_Unload (Cancel As Integer)

    Dim i as integer

    ' Loop through the forms collection and unload

    ' each form.

    For i = Forms.Count – 1 to 0 Step - 1

    Unload Forms(i)

    Next

    End Sub








     



    End statement



    Ends an application immediately: no code after the End statement is executed,
    and no further events occur. Object references will be freed, but if you
    have defined your own classes, Visual Basic will not execute the Terminate
    events of objects created from your classes.



    Life Cycle of Visual Basic Forms

    1.Created, but not loaded. (Initialize) This is the only state all forms
    pass through. 2.Loaded, but not shown. (Load) Create Controls. Assign hWin,
    hDC. 3.Shown.

    (Resize) - Occurs when an object is first displayed or when the window state
    of an object changes. (For example, a form is maximized, minimized, or
    restored.)

    (Activate) - Occurs when an object becomes the active window.

    (Paint) - Occurs when part or all of an object is exposed after being moved
    or enlarged, or after a window that was covering the object has been
    moved. 4.Memory and resources completely reclaimed.

    (QueryUnload) – Prompt user for saving.

    (Unload) - Remove from Forms Collection. Module-level variables may still
    exist.

    The only way to release all memory and resources is to unload the form and
    then set all references to Nothing. Set Form1 = Nothing

    (Terminate)

    Executing the End statement unloads all forms and sets all object variables
    in your program to Nothing. However, this is a very abrupt way to terminate
    program. None of the forms will get their QueryUnload, Unload, or Terminate
    events, and objects created will not get their Terminate events. 5.Unloaded
    and unreferenced while a control is still referenced.







     



    Object Concept



    Objects in Visual Basic are created from classes; thus an object is said to be an instance of a class. The class defines an object’s interfaces, whether the object is public, and under what circumstances it can be created. Descriptions of classes are stored in type libraries, and can be viewed with object browsers.

    To use an object, you must keep a reference to it in an object variable. The type of binding determines the speed with which an object’s methods are accessed using the object variable. An object variable can be late bound (slowest), or early bound. Early-bound variables can be DispID bound or vtable bound (fastest).

    A set of properties and methods is called an interface. The default interface of a Visual Basic object is a dual interface which supports all three forms of binding. If an object variable is strongly typed (that is, Dim … As classname), it will use the fastest form of binding.



     



    Using Code Editor



    In a form module, the list includes a general section, a section for the form itself, and a section for each control contained on the form. For a class module, the list includes a general section and a class section; for a standard module only a general section is shown.

    Class modules list only the event procedures for the class itself — Initialize and Terminate. Standard modules don't list any event procedures, because a standard module doesn't support events.



    Breaking and combining statements



    Text1.Text = "Hello" : Red = 255 : Text1.BackColor = _

    Red





    Declaring Variables








    Dim variablename [As type]

    ••Declaring a variable in the Declarations section of a form, standard, or class module, rather than within a procedure, makes the variable available to all the procedures in the module. •Declaring a variable using the Public keyword makes it available throughout your application. •Declaring a local variable using the Static keyword preserves its value even when a procedure ends.



    Implicit Declaration - You don't have to declare a variable before using it.

    Explicit Declaration - Using "Option Explicit"

    •
    •The Option Explicit statement operates on a per-module basis; it must be placed in the Declarations section of every form, standard, and class module for which you want Visual Basic to enforce explicit variable declarations. If you select Require Variable Declaration, Visual Basic inserts Option Explicit in all subsequent form, standard, and class modules, but does not add it to existing code. You must manually add Option Explicit to any existing modules within a proje<

    Scoping Variables



    Depending on how it is declared, a variable is scoped as either a procedure-level (local) or module-level variable.
    Scope

    Private



    Public



    Procedure-level

    ( Dim, Static )



    Variables are private to the procedure in which they appear.



    Not applicable. You cannot declare public variables within a procedure.



    Module-level

    ( In Declaration Section )



    Variables are private to the module in which they appear.



    Variables are available to all modules.





    Values in local variables declared with Static exist the entire time your application is running while variables declared with Dim exist only as long as the procedure is executing. At the module level, there is no difference between Private and Dim. You can't declare public variables within a procedure.



    Static Function or Sub will make all the local variables in the procedure static regardless their declaration inside.

    Constant has the same scope rule as variable does.



    Friend members is suitable in the ActiveX components. Friend functions are not part of an object's interface. They can't be accessed by programs that use the component's objects. They're only visible to all the other objects within the component to allow safe internal communication within the component.

    Because Friend members aren't part of an object's public interface, they can't be accessed late bound — that is, through variables declared As Object. To use Friend members, you must declare variables with early binding — that is, As classname.



    The Friend keyword can only be used in class modules. However, Friend procedures can be accessed by procedures in any module of a project. A Friend procedure doesn't appear in the type library of its parent class, nor can a Friend procedure be late bound.



    Friend makes the procedure visible throughout the project, but not to a controller of an instance of the object.



     



    Name Conflicting and Resolving



    The forms and controls can have the same name as a restricted keyword. To resolve conflict, using:
    •
    •MyForm.Loop.Visible = True ' Qualified with the form name.

    [Loop].Visible = True ' Square brackets also work.







    Within the form module, local variables with the same names as controls on the form shadow the controls.



    To resolve conflict, using: a reference or keyword Me





    Private Sub Form_Click ()

    Dim Text1 ' Assume there is also a control on the form called Text1.

    Text1 = "Variable" ' Variable shadows control.

    Text1.Top = 0 ' This causes an error!

    Me.Text1.Top = 0 ' Must qualify with Me to get

    End Sub








    A variable in the module cannot have the same name as any procedures or types defined in the module. It can, however, have the same name as public procedures, types, or variables defined in other modules. In this case, when the variable is accessed from another module, it must be qualified with the module name.

    Constant Name is referenced in case of collision depends on which object library has the higher priority.



    To resolve conflict, using: [libname.][modulename.]constname



     



    Data types



    Dim EmpName As String * 50



    Fixed-length strings in standard modules can be declared as Public or Private. In forms and class modules, fixed-length strings must be declared Private. You can assign a string to a numeric variable if the string represents a numeric value.

    The default value of Boolean variable is False.



    Object variable is actual a 32-bit pointer referring to an object within an application or within some other application. Using the Set statement to refer to any actual object recognized by the application.
    •
    •Dim objDb As Object ‘or Database

    Set objDb = OpenDatabase("c:\Vb5\Biblio.mdb")










    By default, if you don't supply a data type, the variable is given the Variant data type. A Variant variable is capable of storing all system-defined types of data. You don't have to convert between these types of data if you assign them to a Variant variable; Visual Basic automatically performs any necessary conversion. For example:





    Dim SomeValue ' Variant by default.

    SomeValue = "17" ' "17" (a two-character string)

    SomeValue = SomeValue - 15 ' numeric value 2

    SomeValue = "U" & SomeValue ' "U2" (a two- character string)





    ••If you perform arithmetic operations on a Variant, the Variant must contain something that is a number. •If you are concatenating strings, use the & operator instead of the + operator. •Variants can contain three special values: Empty, Null, and Error.

    •Empty is used to see if a value has ever been assigned to a created variable.

    •Null is commonly used in database applications to indicate unknown or missing data. Null will propagate through expressions involving Variant variables. Variables are not set to Null unless you explicitly assign Null to them.

    •Error is a special value used to indicate that an error condition has occurred in a procedure. Error values are created by converting real numbers to error values using the CVErr function.






    Note: A variant always takes up 16 bytes, no matter what you store in it. Objects, strings, and arrays are not physically stored in the Variant; in these cases, four bytes of the Variant are used to hold either an object reference, or a pointer to the string or array. The actual data are stored elsewhere.



    ParamArray
    •It can only be used in as the final argument in an argument list. •It represents an optional array of variant Data type •It cannot be used with ByVal, ByRef or Optional keywords •It is used in these contexts:
    ••Declare Statement •Function Statement •Property Get Statement •Property Let Statement •Sub Statement





    You create a user-defined type with the Type statement, which must be placed in the Declarations section of a module.

    User-defined types are always passed by reference.
    •
    •Public Type udtAccount

    Number As Long

    Type As Byte

    CustomerName As String

    Balance As Double

    End Type










    Enumeration data type



    Public Enum WorkDays

    Saturday

    Sunday = 0

    Monday

    Tuesday

    Wednesday

    Thursday

    Friday

    Invalid = -1

    End Enum








     



    Arrays








    Dim Sums(20) As Double ' 21 elements. The default lower bound is 0.



    Dim Counters(1 To 15) As Integer

    Dim MultiD(3, 1 To 10, 1 To 15) 'multi-dimension



    Dim DynArray() 'dynamic array






    ReDim DynArray(4 to 12) 'is an executable statement, can appear only in a procedure



    ReDim Preserve DynArray(UBound(DynArray) + 1) 'reserve the old values





    •
    •
    •
    •
    •
    •ReDim Preserve Matrix(UBound(Matrix, 1) + 1, 10) 'Error: Only the upper bound of the last 'dimension in a multidimensional array can be changed









    You may want to use a collection instead of array if you're working with a small, dynamic set of items.



    A Collection object stores each item in a Variant. A Collection object has three methods (add, item, remove) and one property (count). Collection are not polymorphic. Forms collection contains all of the currently loaded Visual Basic forms in the program. Collection class contains anything that can be stored in a Variant. Thus the Collection object can contain an object or an integer, but not a user-defined type.



    control array



    A group of controls that share a common name, type, and event procedures. Each control in an array has a unique index number that can be used to determine which control recognizes an event.



    There are three ways to create a control array at design time:







    Assign the same name to more than one control.

    Copy an existing control and then paste it onto the form.

    Set the control's Index property to a value that is not Null.

    Note: You must create menu control arrays in the Menu Editor.



    At run time, use:

    Load Object(index%)

    Unload Object(index%)





    •The control must be created at design-time to be ready loaded at run-time. You can use the Unload statement to remove any control created with Load. However, you cannot use Unload to remove controls created at design time.





    Procedure






    Declaration Statement



    [Public | Private] Declare Sub name Lib "libname" [Alias "aliasname"] [([arglist])]

    [Public | Private] Declare Function name Lib "libname" [Alias "aliasname"] [([arglist])] [As type]

    Sub procedures are by default Public in all modules, which means they can be called from anywhere in the application. There are two types of Sub procedures, general procedures and event procedures.



    Sub ButtonManager(Button As Control) ‘general procedure, usually in bas. module

    Private Sub cmdUp_Click() ‘event procedure



    There are two ways to call a Sub procedure:



    ' Both of these statements call a Sub named MyProc.

    Call MyProc (FirstArgument, SecondArgument)

    MyProc FirstArgument, SecondArgument








    Function has return value.

    There are three ways to call a Function procedure:



    X = functionForX

    Call function(x) ‘will throw away return value

    Function x ‘will throw away return value



    Argument








    Sub ListText(ByVal x As String, Optional y As _Integer = 12345)



    Using the ParamArray keyword allows you to specify that a procedure will accept an arbitrary number of arguments.

    ParamArray is used only as the last argument in arglist to indicate that the final argument is an Optional array of Variant elements. The ParamArray keyword allows you to provide an arbitrary number of arguments. The ParamArray keyword can't be used with ByVal, ByRef, or Optional.

    Named argument for many built-in functions, statements, and methods:



    Function ListText(strName As String, Optional strAddress As String)

    List1.AddItem strName

    List2.AddItem strAddress

    End Sub



    Private Sub Command1_Click()

    ListText strAddress:="12345", strName:="Your Name" ‘in reverse order

    End Sub



    Control Structure








    For Each element In group
    statements



    Next element



    This is helpful if you don't know how many elements are in a collection.

    ••For collections, element can only be a Variant variable, a generic Object variable, or an object listed in the Object Browser. •For arrays, element can only be a Variant variable. •You cannot use For Each...Next with an array of user-defined types because a Variant cannot contain a user-defined type.

    •Exit For … Exit Do … Exit Sub … Exit Function ‘exit control structure






    Object








    Properties that you can set and get at run time are called read-write properties. Properties you can only read at run time are called read-only properties.

    There are some common cases in Visual Basic where one object contains other objects. Forms, Controls, Printers.

    Three ways to refer a collection member:

    Controls("List1")

    Controls!List1

    Controls(3)








    You can use the Container property to change an object's container within a form.



    The following controls can contain other controls:
    ••Frame control •Picture box control •Toolbar control (Professional and Enterprise editions only)








    Menu








    Each menu you create can include up to five levels of submenus. Ctrl+E: Menu Editor



    A menu control array is a set of menu items on the same menu that share the same name and event procedures. Each menu control array element is identified by a unique index. Use a menu control array to:
    ••Create a new menu item at run time when it must be a member of a control array. For example, a menu control array may be used to store a list of recently opened files. •Simplify code, because common blocks of code can be used for all menu items.




    Elements of a menu control array must be contiguous in the menu control list box and must be at the same level of indentation. When you're creating menu control arrays, be sure to include any separator bars that appear on the menu.





    What is the restrictions of dynamically created menu items?







    Cannot have shortcut keys

    Cannot be used for a WindowList

    Must be menu control array elements



    Pop-up menu



    Private Sub Form_MouseUp (Button As Integer, Shift As _

    Integer, X As Single, Y As Single)

    If Button = 2 Then ' Check if right mouse button was clicked.

    PopupMenu mnuFile ' Display the File menu as a pop-up menu.

    End If

    End Sub





    •Any code following a call to the PopupMenu method is not run until the user selects an item in the menu or cancels the menu. Only one pop-up menu can be displayed at a time. While a pop-up menu is displayed, calls to the PopupMenu method are ignored. Calls to the PopupMenu method are also ignored whenever a menu control is active.



    Menu and toolbar negotiation will occur only for insertable objects that support in-place activation.

    1.The NegotiateMenus property does not apply to MDI Forms. 2.The NegotiateToolbars property applies only to MDI forms.




    There are three ways to set conditional compilation constants:
    •Project Properties dialog box - Public to all modules in the project •Command line - Public to all modules in the project

    •
    •vb6.exe /make MyProj.vbp /d conFrenchVersion=–1:conANSI=0


    ••#Const statement in code - Private to the module in which they are declared.

    •
    •
    •
    •- Only conditional compiler constants and literals can be used in expression.

    Conditional compilation can use literal statements except for IS operator.







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