1. What
is VB.NET?
Visual Basic .NET
(VB.NET) is an object-oriented computer programming language implemented on the
.NET Framework. Although it is an evolution of classic Visual Basic language,
it is not backwards-compatible with VB6, and any code written in the old version
does not compile under VB.NET.
2. What
is entry point method of VB.NET program?
Sub Main indicates
the entry point of VB.Net program.
3. What
are Shared methods?
Shared methods or
static methods can be invoked without creating an object of the class.
4. What
are Shared variables?
Shared declares a
shared variable, which is not associated with any specific instance of a class
or structure, rather available to all the instances of the class or structure.
5. What
are Shadows variable?
Shadows indicate that
the variable re-declares and hides an identically named element, or set of
overloaded elements, in a base class.
6. What
are Static variable?
Static indicates that
the variable will retain its value, even when the after termination of the
procedure in which it is declared.
7. How to
create a constant in VB.NET?
In VB.Net, constants
are declared using the Const statement. The Const statement is used at module,
class, structure, procedure, or block level for use in place of literal values.
8. What
is the purpose of Ansi keyword in VB.NET?
Ansi − Specifies that
Visual Basic should marshal all strings to American National Standards
Institute (ANSI) values regardless of the name of the external procedure being
declared.
9. What
is the purpose of Assembly keyword in VB.NET?
Assembly − Specifies
that an attribute at the beginning of a source file applies to the entire
assembly.
10. What
is the purpose of Async keyword in VB.NET?
Async − Indicates
that the method or lambda expression that it modifies is asynchronous. Such
methods are referred to as async methods. The caller of an async method can
resume its work without waiting for the async method to finish.
11. What
is the purpose of Auto keyword in VB.NET?
Auto − The
charsetmodifier part in the Declare statement supplies the character set
information for marshaling strings during a call to the external procedure. It
also affects how Visual Basic searches the external file for the external
procedure name. The Auto modifier specifies that Visual Basic should marshal
strings according to .NET Framework rules.
12. What
is the purpose of ByRef keyword in VB.NET?
ByRef − Specifies
that an argument is passed by reference, i.e., the called procedure can change
the value of a variable underlying the argument in the calling code. It is used
under the contexts of −
·
Declare Statement
·
Function Statement
·
Sub Statement
13. What
is the purpose of ByVal keyword in VB.NET?
ByVal − Specifies
that an argument is passed in such a way that the called procedure or property
cannot change the value of a variable underlying the argument in the calling
code. It is used under the contexts of −
·
Declare Statement
·
Function Statement
·
Operator Statement
·
Property Statement
·
Sub Statement
14. What
is the purpose of Default keyword in VB.NET?
Default − Identifies
a property as the default property of its class, structure, or interface.
15. What
is the purpose of Friend keyword in VB.NET?
Friend − Specifies
that one or more declared programming elements are accessible from within the
assembly that contains their declaration, not only by the component that
declares them.
16. Friend access is
often the preferred level for an application's programming elements, and Friend
is the default access level of an interface, a module, a class, or a structure.
17. What
is the purpose of In keyword in VB.NET?
In − It is used in
generic interfaces and delegates.
18. What
is the purpose of Iterator keyword in VB.NET?
Iterator − Specifies
that a function or Get accessor is an iterator. An iterator performs a custom
iteration over a collection.
19. What
is the purpose of Key keyword in VB.NET?
Key − The Key keyword
enables you to specify behavior for properties of anonymous types.
20. What
is the purpose of Module keyword in VB.NET?
Module − Specifies
that an attribute at the beginning of a source file applies to the current
assembly module. It is not same as the Module statement.
21. What
is the purpose of MustInherit keyword in VB.NET?
MustInherit −
Specifies that a class can be used only as a base class and that you cannot
create an object directly from it.
22. What
is the purpose of MustOverride keyword in VB.NET?
MustOverride −
Specifies that a property or procedure is not implemented in this class and
must be overridden in a derived class before it can be used.
23. What
is the purpose of Narrowing keyword in VB.NET?
Narrowing − Indicates
that a conversion operator (CType) converts a class or structure to a type that
might not be able to hold some of the possible values of the original class or
structure.
24. What
is the purpose of NotInheritable keyword in VB.NET?
NotInheritable −
Specifies that a class cannot be used as a base class.
25. What
is the purpose of NotOverridable keyword in VB.NET?
NotOverridable −
Specifies that a property or procedure cannot be overridden in a derived class.
26. What
is the purpose of Optional keyword in VB.NET?
Optional − Specifies
that a procedure argument can be omitted when the procedure is called.
27. What
is the purpose of Out keyword in VB.NET?
Out − For generic
type parameters, the Out keyword specifies that the type is covariant.
28. What
is the purpose of Overloads keyword in VB.NET?
Overloads − Specifies
that a property or procedure redeclares one or more existing properties or
procedures with the same name.
29. What
is the purpose of Overridable keyword in VB.NET?
Overridable −
Specifies that a property or procedure can be overridden by an identically
named property or procedure in a derived class.
30. What
is the purpose of Overrides keyword in VB.NET?
Overrides − Specifies
that a property or procedure overrides an identically named property or
procedure inherited from a base class.
31. What
is the purpose of ParamArray keyword in VB.NET?
ParamArray −
ParamArray allows you to pass an arbitrary number of arguments to the
procedure. A ParamArray parameter is always declared using ByVal.
32. What
is the purpose of Partial keyword in VB.NET?
Partial − Indicates
that a class or structure declaration is a partial definition of the class or
structure.
33. What
is the purpose of Private keyword in VB.NET?
Private − Specifies
that one or more declared programming elements are accessible only from within
their declaration context, including from within any contained types.
34. What
is the purpose of Protected keyword in VB.NET?
Protected − Specifies
that one or more declared programming elements are accessible only from within
their own class or from a derived class.
35. What
is the purpose of Public keyword in VB.NET?
Public − Specifies
that one or more declared programming elements have no access restrictions.
36. What
is the purpose of ReadOnly keyword in VB.NET?
ReadOnly − Specifies
that a variable or property can be read but not written.
37. What
is the purpose of Shadows keyword in VB.NET?
Shadows − Specifies
that a declared programming element redeclares and hides an identically named
element, or set of overloaded elements, in a base class.
38. What
is the purpose of Shared keyword in VB.NET?
Shared − Specifies
that one or more declared programming elements are associated with a class or
structure at large, and not with a specific instance of the class or structure.
39. What
is the purpose of Static keyword in VB.NET?
Static − Specifies
that one or more declared local variables are to continue to exist and retain
their latest values after termination of the procedure in which they are
declared.
40. What
is the purpose of Unicode keyword in VB.NET?
Unicode − Specifies
that Visual Basic should marshal all strings to Unicode values regardless of
the name of the external procedure being declared.
41. What
is the purpose of Widening keyword in VB.NET?
Widening − Indicates
that a conversion operator (CType) converts a class or structure to a type that
can hold all possible values of the original class or structure.
42. What
is the purpose of WithEvents keyword in VB.NET?
WithEvents −
Specifies that one or more declared member variables refer to an instance of a
class that can raise events.
43. What
is the purpose of WriteOnly keyword in VB.NET?
WriteOnly − Specifies
that a property can be written but not read.
44. What
is the purpose of Dim statement in VB.NET?
Dim Statement −
Declares and allocates storage space for one or more variables.
Dim number As
Integer
Dim quantity As Integer = 100
Dim message As
String = "Hello!"
45. What
is the purpose of Const statement in VB.NET?
Const Statement −
Declares and defines one or more constants.
Const maximum As
Long = 1000
Const naturalLogBase As Object
= CDec(2.7182818284)
46. What
is the purpose of Enum statement in VB.NET?
Enum Statement −
Declares an enumeration and defines the values of its members.
Enum CoffeeMugSize
Jumbo
ExtraLarge
Large
Medium
Small
End Enum
47. What
is the purpose of Class statement in VB.NET?
Class Statement −
Declares the name of a class and introduces the definition of the variables,
properties, events, and procedures that the class comprises.
Class Box
Public length As
Double
Public breadth As
Double
Public height As
Double
End Class
48. What
is the purpose of Structure statement in VB.NET?
Structure Statement −
Declares the name of a structure and introduces the definition of the
variables, properties, events, and procedures that the structure comprises.
Structure Box
Public length As
Double
Public breadth As
Double
Public height As
Double
End Structure
49. What
is the purpose of Module statement in VB.NET?
Module Statement −
Declares the name of a module and introduces the definition of the variables,
properties, events, and procedures that the module comprises.
Public Module
myModule
Sub Main()
Dim user As
String =
InputBox("What is your name?")
MsgBox("User name is" & user)
End Sub
End Module
50. What
is the purpose of Interface statement in VB.NET?
Interface Statement −
Declares the name of an interface and introduces the definitions of the members
that the interface comprises.
Public Interface
MyInterface
Sub doSomething()
End Interface
51. What
is the purpose of Function statement in VB.NET?
Function Statement −
Declares the name, parameters, and code that define a Function procedure.
Function
myFunction
(ByVal n As
Integer) As Double
Return 5.87 * n
End Function
52. What
is the purpose of Sub statement in VB.NET?
Sub Statement −
Declares the name, parameters, and code that define a Sub procedure.
Sub mySub(ByVal s As String)
Return
End Sub
53. What
is the purpose of Declare statement in VB.NET?
Declare Statement −
Declares a reference to a procedure implemented in an external file.
Declare Function
getUserName
Lib "advapi32.dll"
Alias "GetUserNameA"
(
ByVal lpBuffer As
String,
ByRef nSize As Integer) As Integer
54. What
is the purpose of Operator statement in VB.NET?
Operator Statement −
Declares the operator symbol, operands, and code that define an operator
procedure on a class or structure.
Public Shared
Operator +
(ByVal x As
obj, ByVal
y As obj)
As obj
Dim r As New obj
' implemention code for r = x + y
Return r
End Operator
55. What
is the purpose of Property statement in VB.NET?
Property Statement −
Declares the name of a property, and the property procedures used to store and
retrieve the value of the property.
ReadOnly Property quote()
As String
Get
Return quoteString
End Get
End Property
56. What
is the purpose of Event statement in VB.NET?
Event Statement −
Declares a user-defined event.
Public Event
Finished()
57. What
is the purpose of Delegate statement in VB.NET?
Delegate Statement −
Used to declare a delegate.
Delegate Function MathOperator(
ByVal x As Double,
ByVal y As Double
) As Double
58. What
is a preprocessor directives in VB.NET?
The VB.Net compiler
directives give instructions to the compiler to preprocess the information
before actual compilation starts. All these directives begin with #, and only
white-space characters may appear before a directive on a line. These
directives are not statements.
59. What
is the purpose of AddressOf operator in VB.NET?
AddressOf − Returns
the address of a procedure.
AddHandler Button1.Click,
AddressOf Button1_Click
60. What
is the purpose of Await operator in VB.NET?
Await − It is applied
to an operand in an asynchronous method or lambda expression to suspend
execution of the method until the awaited task completes.
Dim result As
res
= Await AsyncMethodThatReturnsResult()
Await AsyncMethod()
61. What
is the purpose of GetType operator in VB.NET?
GetType − It returns
a Type object for the specified type. The Type object provides information
about the type such as its properties, methods, and events.
MsgBox(GetType(Integer).ToString())
62. What
is the purpose of Function Expression in VB.NET?
Function Expression −
It declares the parameters and code that define a function lambda expression.
Dim add5 =
Function(num
As
Integer) num + 5
'prints 10
Console.WriteLine(add5(5))
63. What
is the purpose of If operator in VB.NET?
If − It uses
short-circuit evaluation to conditionally return one of two values. The If
operator can be called with three arguments or with two arguments.
64. What
is the purpose of Exit statement in VB.NET?
Exit statement −
Terminates the loop or select case statement and transfers execution to the
statement immediately following the loop or select case.
65. What
is the purpose of Continue statement in VB.NET?
Continue statement −
Causes the loop to skip the remainder of its body and immediately retest its
condition prior to reiterating.
66. What
is the purpose of GoTo statement in VB.NET?
GoTo statement −
Transfers control to the labeled statement. Though it is not advised to use
GoTo statement in your program.
67. What
are dynamic arrays in VB.NET?
Dynamic arrays are
arrays that can be dimensioned and re-dimensioned as par the need of the
program. You can declare a dynamic array using the ReDim statement.
68. What
is Jagged Array in VB.NET?
A Jagged array is an
array of arrays. A Jagged array is an array of arrays. The follwoing code shows
declaring a jagged array named scores of Integers:
Dim scores As
Integer()()
= New Integer(5)(){}
69. What
is ArrayList in VB.NET?
It represents ordered
collection of an object that can be indexed individually. It is basically an
alternative to an array. However, unlike array, you can add and remove items
from a list at a specified position using an index and the array resizes itself
automatically. It also allows dynamic memory allocation, add, search and sort
items in the list.
70. What
is Hashtable in VB.NET?
It uses a key to
access the elements in the collection. A hash table is used when you need to
access elements by using key, and you can identify a useful key value. Each
item in the hash table has a key/value pair. The key is used to access the
items in the collection.
71. What
is SortedList in VB.NET?
It uses a key as well
as an index to access the items in a list. A sorted list is a combination of an
array and a hash table. It contains a list of items that can be accessed using
a key or an index. If you access items using an index, it is an ArrayList, and
if you access items using a key, it is a Hashtable. The collection of items is
always sorted by the key value.
72. What
is Stack in VB.NET?
It represents a
last-in, first out collection of object. It is used when you need a last-in,
first-out access of items. When you add an item in the list, it is called
pushing the item, and when you remove it, it is called popping the item.
73. What
is Queue in VB.NET?
It represents a
first-in, first out collection of object. It is used when you need a first-in,
first-out access of items. When you add an item in the list, it is called
enqueue, and when you remove an item, it is called deque.
74. What
is BitArray in VB.NET?
It represents an
array of the binary representation using the values 1 and 0. It is used when
you need to store the bits but do not know the number of bits in advance. You
can access items from the BitArray collection by using an integer index, which
starts from zero.
In how
many ways a function can return value in VB.NET?
In VB.Net, a function
can return a value to the calling code in two ways −
·
By using the return statement.
·
By assigning the value to the function name.
Can you
create a function in VB.NET which can accept varying number of arguments?
By using the params
keyword, a method parameter can be specified which takes a variable number of
arguments or even no argument.
Can you
pass additional type of parameters after using params in function definition?
No! additional
parameters are not permitted after the params keyword in a method declaration.
Only one params keyword is allowed in a method declaration.
75. Which
class acts as a base class for all exceptions in VB.NET?
VB.NET exceptions are
represented by classes. The exception classes in VB.NET are mainly directly or
indirectly derived from the System.Exception class. Some of the exception
classes derived from the System.Exception class are the
System.ApplicationException and System.SystemException classes.
76. What
is the difference between System.ApplicationException class and
System.SystemException class?
The
System.ApplicationException class supports exceptions generated by application
programs. Hence the exceptions defined by the programmers should derive from
this class. The System.SystemException class is the base class for all
predefined system exception.
77. What
is a stream in VB.NET?
The stream is
basically the sequence of bytes passing through the communication path. There
are two main streams: the input stream and the output stream. The input stream
is used for reading data from file (read operation) and the output stream is
used for writing into the file (write operation).
78. Which
class in VB.NET helps in reading from, writing to and closing files?
The FileStream class
in the System.IO namespace helps in reading from, writing to and closing files.
This class derives from the abstract class Stream.
79. Briefly
explain StreamReader class.
The StreamReader
class inherits from the abstract base class TextReader that represents a reader
for reading series of characters. It is used for reading from text files.
80. Briefly
explain StreamWriter class.
The StreamWriter
class inherits from the abstract class TextWriter that represents a writer,
which can write a series of character. It is used for writing to text files.
81. Briefly
explain BinaryReader class.
The BinaryReader class
is used to read binary data from a file. A BinaryReader object is created by
passing a FileStream object to its constructor. The BinaryReader class is used
for reading from a binary file.
82. Briefly
explain BinaryWriter class.
The BinaryWriter
class is used to write binary data to a stream. A BinaryWriter object is
created by passing a FileStream object to its constructor. The BinaryWriter
class is used for writing to a binary file.
83. Explain
usage of DirectoryInfo class.
The DirectoryInfo
class is derived from the FileSystemInfo class. It has various methods for
creating, moving, and browsing through directories and subdirectories. This
class cannot be inherited.
84. Explain
usage of FileInfo class.
The FileInfo class is
derived from the FileSystemInfo class. It has properties and instance methods
for creating, copying, deleting, moving, and opening of files, and helps in the
creation of FileStream objects. This class cannot be inherited.
85. What
are the components of a Visual Basic Control?
Every Visual Basic
control consists of three important elements −
·
Properties − Describes the object.
·
Methods − Cause an object to do
something.
·
Events − Happens when an object does
something.
86. What
is the purpose of VB.NET Form control?
It represents the
container for all the controls that make up the user interface.
87. What
is the purpose of VB.NET TextBox control?
It represents a
Windows text box control.
88. What
is the purpose of VB.NET Label control?
It represents a
standard Windows label.
89. What
is the purpose of VB.NET Button control?
It represents a
Windows button control.
90. What
is the purpose of VB.NET ListBox control?
It represents a
Windows control to display a list of items.
91. What
is the purpose of VB.NET ComboBox control?
It represents a
Windows combo box control.
92. What
is the purpose of VB.NET RadioButton control?
It enables the user
to select a single option from a group of choices when paired with other
RadioButton controls.
93. What
is the purpose of VB.NET PictureBox control?
It represents a
Windows picture box control for displaying an image.
94. What
is the purpose of VB.NET ProgressBar control?
It represents a
Windows progress bar control.
95. What
is the purpose of VB.NET ScrollBar control?
It Implements the
basic functionality of a scroll bar control.
96. What
is the purpose of VB.NET DateTimePicker control?
It represents a
Windows control that allows the user to select a date and a time and to display
the date and time with a specified format.
97. What
is the purpose of VB.NET TreeView control?
It displays a
hierarchical collection of labeled items, each represented by a TreeNode.
98. What
is the purpose of VB.NET ListView control?
It represents a
Windows list view control, which displays a collection of items that can be
displayed using one of four different views.