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VB.NET

Q1.Introduction of visual basic?

Ans-:visual basic is a third generation event driven programming language &

integrated development environment from Microsoft for its released in

1991.Microsoft intended visual basic to relating easy to learn and use.

Elements of Visual Basic-:The two basic elements of visual basic are GUI and the

code associated with the application that makes it respond to event occurred as a

result of a user action.

Elements-: IDE is a term commonly used in the programming world to described

the interface and environment that we use to create our applications. it is called

integrated because we can access virtually all of the development tools that we

need from one screen called on interface. The IDE is also commonly referred to as

the design environment or the program.

The visual basic IDE is made up of a number of components-:

IDE-: Integrated Development Environment

1. Menu bar

2. Tool bar

3. Project explorer

4. Properties window

5. from layout window

6. Toolbar

7. from designer

8. Object browser

Introduction of VB.Net-:VB.Net is a simple modern, object oriented computer

programming language developed by Microsoft to combine the power of.net

framework and the common language runtime with the productivity benefits that

are hallmark of visual basic.

Vb.net has complete support for object oriented concepts. Everything in vb.net is

an object including all of the primitive types (short, integer, long, string, Boolean

etc) and user defined types, events and event assembler. All objects inherit from

the basic class objects.

V . et fra e ork is i ple e t y Mi rosoft’s net framework.therfore it has full

access to all the libraries in the .net framework. It is also possible to run vb.net

program on mono the open source alternative to .net not only under window but

even Linux or Mac OSx.

The following reasons make vb.net a widely used professional language-:

1. Modern general purpose

2. Object oriented

3. Component oriented

4. easy to learn

5. Structured programming

6. It produces efficient programming

7. It can be complied on a variety of computer platform.

8. Part of net. Framework

The .Net framework The .net framework is a revolutionary platform that helps you to write the

following types of applications.

1) Window applications

2) Web applications

3) Web services

The .net framework applications are multiplatform applications. The

framework has been designed in such a way that it can be used from any of

the following languages visual basic, c#, c++, java script and Cobol etc.

The .net framework consists of an various library of codes used by the client

language like vb.net.these language use object oriented methodology.

There is some following same of the components of the .net framework.

common language runtime(CLR)

the .net framework class library

Common language specification.

Common type system

Metadata and assembler

Windows forms

Asp.net and asp.net Ajax

Ado.net

Window workflow foundation(wf)

Window presentation foundation(wcf)

Window communication foundation(wcf)

Linq

Review Q1what are the two major features of visual basic?

Ans-:1) GUI Interface-:vb is a graphical user interface language. This means that a

vb program will always show something on the screen that the user can interact e

with (usually via mouse and keyboard) to get a job done.

2) Modularization-: it is considered good programming practice to modular your

programs. Instead of thinking of a computer program as a single large collections

of code the good programming writes code so that you never need to lock at

more code than fits on the screen(or page)at one time.

3)Object orientation-: object oriented programming is a concept where the

programming thinks of the program in objects that interact with each others. In

oop all the code associated with that object is in one place.

Q2.Write a short note on CLR?

Ans-: CLR stands for common language runtime. It is a managed execution

environment that is a part of Mi rosoft’s et fra e ork. lr a ages the execution of programs written in different supported language clr transforms

source code into a form of bytes code from known common intermediate

language(cil) at runtime clr handles the execution of the cil code.

Q3. What is managed code?

Ans-:managed code is a term coined by Microsoft to identify computers

programming code that requires and will execute only under the management of

a common language runtime virtual machine typically the net framework mono

managed code usually refer to program written in .net language such as c# or

visual basic.net while in managed code refer to program written in c,c++,visual

basic and other language that do not need a runtime to execute.

Q4.Why is JIT needed?

Ans-:jit stands for just in time. Just in time compilation the process of converting

cil to machine code translation. In .net word it is done by jit complier code in

dynamic memory. It means that you will compile yours application twice that you

will compile your applications twice if you run it two times simultaneously.

Q5.What do you mean by MSIL?

Ans-: MSIL stand for Microsoft intermediate language. We can call it as

intermediate language (il) or common intermediate language.

During the compile time the complier convert the source code into

Microsoft intermediate language (msil).Microsoft intermediate language is a cpu

independent set of instructions that can be efficiently converted to the negative

code. During the runtime the common language runtime the common language

ru ti e lr ’s just i time (jit) compiler converts the Microsoft intermediate

language (msil) code into native code to the operating system.

Q6.Explain the concept of assemblies?

Ans-: Microsoft .net assembly is a logical unit of a code that contain code which

the commonly language runtime (clr) executes. It is the smallest unit of

development of a .net applications and it can be .dll or an exe. Assembly is really

Collections of types a d resour e i for atio ’s that are uild to ork together and from a logical unit of functionality. Assemblies are the building block of .net

framework applications. During the compile time metadata is created with

Microsoft intermediate language (msil) and stored in a file called assembly

manifest. Both metadata and Microsoft intermediate language together wrapped

in a portable executable (pe) file.

Q.7 What is CTS?

Ans-: Common type systems (cts) describe a set of types that can be used in

different .net language in common. That is the common type systems (cts) ensure

that objects written in different .net languages can interact with each other. For

communicating between programs written in any .net complaints language the

types have to be compatibles on the basic level.

These types can be value types or reference type. The values types are passed by

values are stored in the stack. The reference type are passed by reference and

stored in the heap. Common type systems (cts) provide base set of data types

which is responsible for cross language integrated. The common language

runtime(clr) can load and execute the source code written in any .net language

only if the types Is described in the common type system(cts).most of the

members defined by types in the .net framework class library (fcl) are common

language specification(cls) complaint types.

Q.Differentiate between values and reference types?

Ans-: value types-: the value types are passed by values and stored in the stack.

When you created a value types a single space in memory is allocated to store the

value and that variable directly holds a value. If you assign it to another variable

the value is copied directly and both variables work independently .predefined

datatypes,structure,enum are also value types and work in the same way values

a d stored i sta k e ory e ause of this gar arge olle tor a ’t a ess the stack.

Reference types-: the reference types are passed by reference and stored in the

heap. Reference type are used by a reference which holds a reference (address)

to the object but not the object itself.beacuse reference types represent the

address of the variable rather than the data itself.beacause reference types

represent the address of the variable rather than the data itself assigning a

refere e aria le to a other does ’t opy the data. Refere e type aria le are stored in a different area of memory called the heap. This means that when a

reference type’s variable is no longer used, it can be marked for garbage

collection. Example of reference types are classes, objects, array, and indexes

interfaces etc.

Q Explain the different kinds of literals?

Ans-: a literal is a textual representation of a particular value of a type. Literal

types include Boolean, integer, floating point string, character and data.

UNIT-2 Q Define a variable?

Ans-: variable are used to store data. a variable as a name to which we refer and

the data type the type of data the variable holds.a variable is nothing but a name

given to storage area that our programs can manipulate. Each variable in vb.net

has a spe ifi type hi h deter i es the size a d layout of the aria le’s e ory the rangeof values that can be stored with in that memory and set of operations

that can be memory and set of operations that can be applied to the variable.we

have already discussed various data types.the basic value type provided in vb.net

can be categorized as-:

Integer,float,decimal,Boolean,data types

Q Declaring of variable?

Ans-: the dim statement is used for variable declaration and storage allocation for

one or more variables. The dim statement is used at module class structure

procedure or block level variables are declared with the dim keyword.dim stands

for dimensions.

Some valid variable declarations along with their definitions are show here-:

Dim studentid as integer

Dim studentsname as string

Dim salary as double

Dim count1,count2 as integer

Dim status as Boolean

Dim exit button as new style system win down forms button

Dim lasttime,next time as date.

Variable intilization in vb.net-:

Variable are initized (assigned a value) with an equal sign followed by a constant

expression.the general form of initialization is-:

Variable _name=value;

For example-:

Dim As Integer

A=15;

You can initialize a variable at the time of declaration as follows-:

Dim StudentID As Integer=100;

Di “tude tNa e As “tri g= Bill “ ith

Example-:

Modules Variable N data Types

Sub Main()

Dim a As Integer=10

Dim b As Integer=5

Dim c As Integer

C=a+b;

Co sole.WriteLi e su of a& = &

End Sub

End Module

Q Scope of variable?

Ans-:the scope of an element in code that can refer to it without qualifying its

a e stated other ay a ele e t’s scope is its accessibility in code.scope is

normally used when writing large programs as large programs divide code into

different classes,modules etcthe different kinds of scope avialible in vb.net are as

follows-:

1)Block Scope-:the element declared is available only within the code block in

which it is declared.

2)Procedure Scope-:The element declared is available only with in the procedure

in which it is declared.

3)Module Level-:the element is available to all code within the module and class

in which it is declared.

4) Namespace Scope-: the element declared is available to all code in the

namespaces.

QVB.NET operators?

ANS-: there are various operators in vb.net.

1) Arithmetic operator

2) Relational operator

3) Logical operator

4) Assignment operator

1) Arithmetic operator-: arithmetic operator is used to mathematical calculations

such as +,-,*,/,% etc.assume variable a hold 2 and b hold 7 then

Operator Description Example

+ Adds two operands A + B will give 9

- Subtracts second operand from the first A - B will give -5

* Multiplies both operands A * B will give 14

/ Divides one operand by another and

returns a floating point result B / A will give 3.5

\ Divides one operand by another and

returns an integer result B \ A will give 3

MOD Modulus Operator and remainder of after

an integer division B MOD A will give 1

Module Module1

Sub Main()

Dim a As Integer=10

Dim b As Integer=20

Console.WriteLine (a+b)

Console.WriteLine (a-b)

Console.WriteLine (a*b)

Console.WriteLine (a%b)

Console.WriteLine (a/b)

End Sub

End Module

2) Relational operator-: this operator is used to compare two values. It is also

called as compression operator. Assume variable a hold 10 and variable b hold 20

then-:


=

Checks if the values of two operands are

equal or not; if yes, then condition

becomes true.

(A = B) is not true.

<>

Checks if the values of two operands are

equal or not; if values are not equal, then

condition becomes true.

(A <> B) is true.

>

Checks if the value of left operand is

greater than the value of right operand; if

yes, then condition becomes true.

(A > B) is not true.

< Checks if the value of left operand is less

than the value of right operand; if yes, then (A < B) is true.

condition becomes true.

>=

Checks if the value of left operand is

greater than or equal to the value of right

operand; if yes, then condition becomes

true.

(A >= B) is not true.

<=

Checks if the value of left operand is less

than or equal to the value of right operand;

if yes, then condition becomes true.

(A <= B) is true.

Module Module1

Sub Main()

Dim a As Integer=10

Dim b As Integer=5

Console.WriteLine (a>b)

Console.WriteLine (a<b)

Console.WriteLine (a=b)

Console.WriteLine (a>=b)

Console.WriteLine (a<=b)

Console.WriteLine (a!=b)

End Sub

End Module

4)Logical operator-:the logical operator supporting by vb.net assume variable a

hold Boolean value true and variable 3 holds Boolean value false then-:


And

It is the logical as well as bitwise AND

operator. If both the operands are true,

then condition becomes true. This operator

does not perform short-circuiting, i.e., it

evaluates both the expressions.

(A And B) is False.

Or

It is the logical as well as bitwise OR

operator. If any of the two operands is true,

then condition becomes true. This operator

(A Or B) is True.

does not perform short-circuiting, i.e., it

evaluates both the expressions.

Not

It is the logical as well as bitwise NOT

operator. Use to reverses the logical state

of its operand. If a condition is true, then

Logical NOT operator will make false.

Not(A And B) is True.

AND Module Module1

Sub Main()

Dim age As Integer=18

Dim height As Integer=155

If((age>18)and(height=155))Then

Console.WriteLine ( you are eligi le )

Else

Console.WriteLine ( you are ot eligi le )

EndIf

End Sub

End Module

OR Module Module1

Sub Main()



If((age>18)OR(height=155))Then

Co sole.WriteLi e you are eligi le

Else

Co sole.WriteLi e you are ot eligi le

EndIf

End Sub

End Module

NOT Module Module1

Sub Main()


If(Not age=18)Then

Co sole.WriteLi e you are eligi le

Else

Co sole.WriteLi e you are ot eligi le

EndIf

End Sub

End Module

4) Assignment operator-:these are following assignement operators supported by

vb.net-:


=

Simple assignment operator, Assigns values

from right side operands to left side

operand

C = A + B will assign value

of A + B into C

+=

Add AND assignment operator, It adds right

operand to the left operand and assigns the

result to left operand

C += A is equivalent to C =

C + A

-=

Subtract AND assignment operator, It

subtracts right operand from the left

operand and assigns the result to left

operand

C -= A is equivalent to C = C

- A

*=

Multiply AND assignment operator, It

multiplies right operand with the left

operand and assigns the result to left

operand

C *= A is equivalent to C =

C * A

/=

Divide AND assignment operator, It divides

left operand with the right operand and

assigns the result to left operand (floating

point division)

C /= A is equivalent to C = C

/ A

QData types in vb.net?

Ans-:A data type is a class that is primarily used just to hold the data.vb.net has

huge no of data types-: store any kind of data more over all the data types used

vb.net are the objects.Vb.net has a number of predefined data types-:

Data Type Storage

Allocation Value Range

Boolean

Depends on

implementing

platform

True or False

Byte 1 byte 0 through 255 (unsigned)

Char 2 bytes 0 through 65535 (unsigned)

Date 8 bytes 0:00:00 (midnight) on January 1, 0001 through

11:59:59 PM on December 31, 9999

Decimal 16 bytes

0 through +/-

79,228,162,514,264,337,593,543,950,335 (+/-

7.9...E+28) with no decimal point; 0 through +/-

7.9228162514264337593543950335 with 28 places

to the right of the decimal

Double 8 bytes

-1.79769313486231570E+308 through -

4.94065645841246544E-324, for negative values

4.94065645841246544E-324 through

1.79769313486231570E+308, for positive values

Integer 4 bytes -2,147,483,648 through 2,147,483,647 (signed)

Long 8 bytes -9,223,372,036,854,775,808 through

9,223,372,036,854,775,807(signed)

Object

4 bytes on 32-

bit platform

8 bytes on 64-

bit platform

Any type can be stored in a variable of type Object

SByte 1 byte -128 through 127 (signed)

Short 2 bytes -32,768 through 32,767 (signed)

Single 4 bytes

-3.4028235E+38 through -1.401298E-45 for negative

values;

1.401298E-45 through 3.4028235E+38 for positive

values

String

Depends on

implementing

platform

0 to appro0 to approximately 2 billion Unicode

characters

UNIT-3 DECISION MAKING AND LOOPING

Decision marking statement-: decision making structures require that the

programmer specify one or more conditions to be evaluated or tested by the

program along with a statement or statement to be executed. If the condition is

determined to be true and optionally other statement to be executed if the

condition is determined to be false. Decision making statement is two types.

1) Iteration/looping statement

2) Conditional statement

Looping statement in vb.net-: there may be a situation when you need to execute

a block of code several number of times. In general, statements are executed

sequentially .a loop statement allows use to execute a statement or group of

statement multiple times and followings is the general form of a loop statement

in most of programming languages.

There are many loops in vb.net.

1) Do loop-: it repeats the enclosed block of statement while a Boolean condition

become true .it could be terminated at any time with the exit do statement.

The syntax of this loop is-:

Do

Statement

Incre/decrement

Loop While(condition)

End Loop

Example-:

Module Module1

Sub Main()

Dim a As Integer=1

Do

Co sole.WriteLi e a

A=a+1

Loop While(a<=10)

End Sub

End Module

2)For Next Loop-:it repeats a group of statement a specified number of times and

a loop index counts the number of loop iterations as the loop executes.

The syntax for this loop as-:

For Counter [As Data Types] =Start to end

[Statement]

[Condition For]

[Statement]

[Exit For]

[Statement]

Next [Counter]

Example-:

Module Module1

Sub Main ()

Dim a As Integer

For a=1 To 20

Console.WriteLine (a)

Next

End Sub

End Module

3) While End While loop-: it execute a series of statement as long as a given

condition is true.


While Condition

[Statements]

[Condition While]

[Statements]

[Exit While]

[Statement]

End While

Example-:

Module Module1

Sub Main ()

Dim a As Integer=1

While (a<=20)


A=a+1

End Sub

End Module

4) For each next loop-: it repeats a group of statements for each element in a

collection. This loop is used for accessing and manipulating all elements in an

array or a vb.net collection.


For Each element[As data type] In group

[Statements]

[Condition For]

[Statements]

[Exit For]

[Statement]

Next[element]

Example-:

Module Module1

Sub Main ()

Dim a As Integer

For a=1 To 20


Next

End Sub

End Module

DECISION MAKING Statement

1)IF then Statement-: it is the simplest form of control statement. If the

condition is true then if block of code will be executed otherwise this are

specified.

Syntax-:

IF Condition Then

Statements

End If

Example-:

Module Module1

Sub Main()



If((a>b)Then

Co sole.WriteLi e a is greater

EndIf

End Sub

End Module

2)IF THEN ELSE STATEMENT-:an if statement can be followed by an optional else

statement which executes when the Boolean is false.

Syntax-:

IF Condition Then

Statements

Else

Statement

End If

Example-:

Module Module1

Sub Main ()



If ((a>b) Then

Co sole.WriteLi e a is greater

Else

Co sole.WriteLi e is greater

End If

End Sub

End Module

3)IF ELSE IF STATEMENT-:an if statement can be followed by an optional else. If

else statement which is very useful to test various conditions using single if else if

statement.

Syntax-:

IF(Boolean expression1)Then

Statements

Else If(Boolean expression2)Then

Statement

Else

Statement

End If

Example-:

Module Module1

Sub Main()

Dim day As Integer=5

If(day=1)Then

Console.WriteLine ( Sunday

Else If(day=2)Then

Co sole.WriteLi e Mo day

Else If(day=3)Then

Co sole.WriteLi e Tuesday

Else

Console.WriteLine ( I alid day

End If

End Sub

End Module

4) NESTED IF STATEMENT-: it is always legal in vb.net to nest if then else

statement. Which means you can use one if or else if statement

Inside another if else if statement.

Syntax-:

IF(Boolean expression1)Then

Statements 1

Else If(Boolean expression2)Then

Statement 2

End If

End If

Example-:

Module Module1

Sub Main()

Dim a As Integer=1000

Dim a As Integer=2000

If(daa=100)Then

If(b=200)Then

Co sole.WriteLi e a is 100 and b is 200

End If

End If

End Sub

End Module

5)SELECT CASE STATEMENT-: a select case statement allows a variable to be

tested for equality against a list of values. Each value is called a case and the

variable being switched on is checked for each select case.

Syntax-:

Select [Case] expression

[Case expression list

[Statements 1]]

[Case Else

[else Statement 2]]

End select

Example-:

Module Module1

Sub Main()

Dim day As Integer=5

Select Case day

Case 1

Co sole.WriteLi e Sunday

Case 2

Co sole.WriteLi e Mo day

Case 3

Co sole.WriteLi e Tuesday

Case 4

Co sole.WriteLi e Wed esday

Case ELSE

Co sole.WriteLi e I alid Day

End Select

End Sub

End Module

UNIT-4

Array ARRAY-:an array stores a fixed size sequential collection of elements of the same

types.an array is used to store a collection of data but it is often more useful to

think of an array as a collection of variables of the same type.

All array consist of contiguous memory locations.the lowest address corresponds

to the first element and the highest address to the last element.

Declaration of an array-: to declare an array in vb.net you use the Dim

statement.

For example-: Dim int Data (30) -an array of 31 elements

Dim Str(20) As string -an array of 21 strings

Initialization of array in vb.net-: you can also initialize the array elements which

declaring while declaring the array.

for example-: Dim int Data() As Integer={12,16,20,24,28,32}

Di a es As stri g={ karthik , sa dly }

The elements in an array can be stored and accessed by using the index of the

array. The following programs demostatrets .

Module arrayAP1

Sub Main()

Dim n(10) As Integer

Dim I,j As Integer

For i=0 To 10

N(i)=i+100

Next i

For j=0 To 100

Co sole.WriteLi e ele e t is ={ } ,j, j

Next j

End Sub

End Module

MULTIDIMENSIONAL ARRAY-:vb.net allow multideminsional array.

multideminsional array are also called rectangle arrays.you can dclare

multideminsional array of strings are

Dim Two Dstring Array(10,20)As String or

threedeminsional array of Integer Variables

example-:

Module arrayAP1

Sub Main()

Dim a() As Integer={{0,0},{1,2},{2,4},{3,6},{4,8}}

Dim i,j As Integer

For i=0 To 4

For J=0 To 1

Co sole.WriteLi e a [{ },{ }]={ } ,i,j,a(i,j))

Next j

Next i

End Sub

End Module

The Array Class(System.Array Class)

The Array class is the base class for all the arrays in VB.Net. It is defined in the

System namespace. The Array class provides various properties and methods to

work with arrays.

Properties of the Array Class

The following table provides some of the most commonly used properties of the

Array class:

S.N Property Name & Description

1 IsFixedSize

Gets a value indicating whether the Array has a fixed size.

2 IsReadOnly

Gets a value indicating whether the Array is read-only.

3

Length

Gets a 32-bit integer that represents the total number of elements in all the

dimensions of the Array.

4

LongLength

Gets a 64-bit integer that represents the total number of elements in all the

dimensions of the Array.

5 Rank

Gets the rank (number of dimensions) of the Array.

Methods of the Array Class

The following table provides some of the most commonly used methods of the

Array class:

S.N Method Name & Description

1

Public Shared Sub Clear (array As Array, index As Integer, length As Integer)

Sets a range of elements in the Array to zero, to false, or to null, depending

on the element type.

2

Public Shared Sub Copy (sourceArray As Array, destinationArray As Array,

length As Integer)

Copies a range of elements from an Array starting at the first element and

pastes them into another Array starting at the first element. The length is

specified as a 32-bit integer.

3

Public Sub CopyTo (array As Array, index As Integer)

Copies all the elements of the current one-dimensional Array to the specified

one-dimensional Array starting at the specified destination Array index. The

index is specified as a 32-bit integer.

4

Public Function GetLength (dimension As Integer) As Integer

Gets a 32-bit integer that represents the number of elements in the specified

dimension of the Array.

5

Public Function GetLongLength (dimension As Integer) As Long

Gets a 64-bit integer that represents the number of elements in the specified

dimension of the Array.

6 Public Function GetLowerBound (dimension As Integer) As Integer

Gets the lower bound of the specified dimension in the Array.

7 Public Function GetType As Type

Gets the Type of the current instance (Inherited from Object).

8 Public Function GetUpperBound (dimension As Integer) As Integer

Gets the upper bound of the specified dimension in the Array.

9

Public Function GetValue (index As Integer) As Object

Gets the value at the specified position in the one-dimensional Array. The

index is specified as a 32-bit integer.

10

Public Shared Function IndexOf (array As Array,value As Object) As Integer

Searches for the specified object and returns the index of the first occurrence

within the entire one-dimensional Array.

11

Public Shared Sub Reverse (array As Array)

Reverses the sequence of the elements in the entire one-dimensional Array.

12 Public Sub SetValue (value As Object, index As Integer)

Sets a value to the element at the specified position in the one-dimensional

Array. The index is specified as a 32-bit integer.

13

Public Shared Sub Sort (array As Array)

Sorts the elements in an entire one-dimensional Array using the IComparable

implementation of each element of the Array.

14

Public Overridable Function ToString As String

Returns a string that represents the current object (Inherited from Object)

UNIT-4 BUILT IN FUNCTIONS VB.NET FUNCTIONS

A function is similar to a normal procedure but the main purpose of the function

is to accept a certain input from the user and return a value which is passed on

to the main program to finish the execution.function is a method which retirn

value function are used to evaluate data make calculation or transfer

data.decalring a function is similar to declaring a sub procedure function are

declared with the function keyword.

For ex-:

Module Function

Sub Main()

Co sole.WriteLi e su is = &add

End Sub

Public Function Add() As Interger

Dim I,j As Integer

I=10

J=20

Return(i+j)

End Function

End Module

There are two types of functions-:

1.MsgBox() Function

2. InputBox ( ) functions.

1.MsgBox() Function-: The objective of MsgBox is to produce a pop-up message

box and prompt the user to click on a command button before he/she can

continues. This format is as follows:

yourMsg=MsgBox (Prompt, Style Value, Title)

The first argument, Prompt, will display the message in the message box. The

Style Value will determine what type of command buttons appear on the message

box. The Title argument will display the title of the message board.

2. InputBox ( ) functions-:An InputBox( ) function will display a message box

where the user can enter a value or a message in the form of text. The format is:

myMessage=InputBox(Prompt, Title, default_text, x-position, y-position)

myMessage is a variant data type but typically it is declared as string, which

accept the message

input by the users. The arguments are explained as follows:

-Prompt - The message displayed normally as a question asked.

-Title - The title of the Input Box.

-default-text -The default text that appears in the input field where users can use

it as his intended input or he may change to the message he wish to key in.

-x-position and y-position - the position or the coordinate of the input box.

Type Conversion Functions-: VB.NET supports many inbuilt conversion functions

that handle the conversion of date and time, character strings, numbers and

more.

Val Function

Val FunctionIt returns the numbers contained in a string as a numeric value of

appropriate type. The Val function stops reading the string at the first character it

cannot recognize as part of a number. Symbols and characters that are often

considered parts of numeric values, such as dollar signs and commas, are not

recognized.

The Str(or Str$) Function-: It is used to return string equivalent for the specified

integer. Public Shared Function Str(ByVal Number As Object) As String.

Subroutine Functions-:

A subroutine is a block of statements that carries out a well-defined task. The

block of statements is placed within a set of Sub. . .End Sub statements and can

be invoked by name. The following subroutine displays the current date in a

message box and can be called by its

name, ShowDate():

Sub ShowDate()

MsgBox(Now().ToShortDateString)

End Sub

UNIT-6 CLASS & OBJECT

Class-: A class definition starts with the keyword Class followed by the class

name; and the class body, ended by the End Class statement. Following is the

general form of a class definition:

Syntax-:Class Classname

Statement

End Class

attributelist is a list of attributes that apply to the class. Optional.

accessmodifier defines the access levels of the class, it has values as -

Public, Protected, Friend, Protected Friend and Private. Optional.

Shadows indicate that the variable re-declares and hides an identically

named element, or set of overloaded elements, in a base class. Optional.

MustInherit specifies that the class can be used only as a base class and

that you cannot create an object directly from it, i.e., an abstract class.

Optional.

NotInheritable specifies that the class cannot be used as a base class.

Partial indicates a partial definition of the class.

Inherits specifies the base class it is inheriting from.

Implements specifies the interfaces the class is inheriting from.

Module mybox

Class Box

Public length As Double

Public breadth As Double

Public height As Double

End Class

Sub Main()

Dim Box1 As Box = New Box()


Dim volume As Double = 0.0

Box1.height = 5.0

Box1.length = 6.0

Box1.breadth = 7.0

Box2.height = 10.0

Box2.length = 12.0

Box2.breadth = 13.0

volume = Box1.height * Box1.length * Box1.breadth

Console.WriteLine("Volume of Box1 : {0}", volume)

volume = Box2.height * Box2.length * Box2.breadth


Console.ReadKey()

End Sub

End Module

When the above code is compiled and executed, it produces the following result:

Volume of Box1 : 210


Member Functions and Encapsulation

A member function of a class is a function that has its definition or its prototype

within the class definition like any other variable. It operates on any object of the

class of which it is a member and has access to all the members of a class for that

object.

Member variables are attributes of an object (from design perspective) and they

are kept private to implement encapsulation. These variables can only be

accessed using the public member functions.

above concepts to set and get the value of different class members in a class:

Module mybox

Class Box

Public length As Double

Public breadth As Double

Public height As Double

Public Sub setLength(ByVal len As Double)

length = len

End Sub

Public Sub setBreadth(ByVal bre As Double)

breadth = bre

End Sub

Public Sub setHeight(ByVal hei As Double)

height = hei

End Sub

Public Function getVolume() As Double

Return length * breadth * height

End Function

End Class

Sub Main()



Dim volume As Double = 0.0

Box1.setLength(6.0)

Box1.setBreadth(7.0)

Box1.setHeight(5.0)

Box2.setLength(12.0)

Box2.setBreadth(13.0)

Box2.setHeight(10.0)

volume = Box1.getVolume()


volume = Box2.getVolume()


Console.ReadKey()

End Sub

End Module




Constructors and Destructors

Constructors

A class constructor is a special member Sub of a class that is executed whenever

we create new objects of that class. A constructor has the name New and it does

not have any return type.

Following program explains the concept of constructor:

Class Line

Private length As Double

Public Sub New()

Console.WriteLine("Object is being created")

End Sub


length = len

End Sub

Public Function getLength() As Double

Return length

End Function

Shared Sub Main()

Dim line As Line = New Line()

line.setLength(6.0)

Console.WriteLine("Length of line : {0}", line.getLength())

Console.ReadKey()

End Sub

End Class


Object is being created

Length of line : 6

Default constructor

A default constructor does not have any parameter, but if you need, a constructor

can have parameters. Such constructors are called parameterized constructors.

This technique helps you to assign initial value to an object at the time of its

creation as shown in the following example:

Class Line


Public Sub New(ByVal len As Double)

Console.WriteLine("Object is being created, length = {0}", len)

length = len

End Sub


length = len

End Sub


Return length

End Function

Shared Sub Main()

Dim line As Line = New Line(10.0)

Console.WriteLine("Length of line set by constructor : {0}", line.getLength())

line.setLength(6.0)

Console.WriteLine("Length of line set by setLength : {0}", line.getLength())

Console.ReadKey()

End Sub

End Class


Object is being created, length = 10

Length of line set by constructor : 10

Length of line set by setLength : 6

Destructor A destructor is a special member Sub of a class that is executed whenever an

object of its class goes out of scope.

A destructor has the name Finalize and it can neither return a value nor can it

take any parameters. Destructor can be very useful for releasing resources before

coming out of the program like closing files, releasing memories, etc.

Destructors cannot be inherited or overloaded.

Following example explains the concept of destructor:

Class Line


Public Sub New()

Console.WriteLine("Object is being created")

End Sub

Protected Overrides Sub Finalize()

Console.WriteLine("Object is being deleted")

End Sub


length = len

End Sub


Return length

End Function

Shared Sub Main()

Dim line As Line = New Line()

line.setLength(6.0)

Console.WriteLine("Length of line : {0}", line.getLength())

Console.ReadKey()

End Sub

End Class


Object is being created

Length of line : 6

Object is being deleted

Shared Members of a VB.Net Class

We can define class members as static using the Shared keyword. When we

declare a member of a class as Shared, it means no matter how many objects of

the class are created, there is only one copy of the member.

The keyword Shared implies that only one instance of the member exists for a

class. Shared variables are used for defining constants because their values can be

retrieved by invoking the class without creating an instance of it.

Shared variables can be initialized outside the member function or class

definition. You can also initialize Shared variables inside the class definition.

You can also declare a member function as Shared. Such functions can access only

Shared variables. The Shared functions exist even before the object is created.

The following example demonstrates the use of shared members:

Class StaticVar

Public Shared num As Integer

Public Sub count()

num = num + 1

End Sub

Public Shared Function getNum() As Integer

Return num

End Function

Shared Sub Main()

Dim s As StaticVar = New StaticVar()

s.count()

s.count()

s.count()

Console.WriteLine("Value of variable num: {0}", StaticVar.getNum())

Console.ReadKey()

End Sub

End Class


Value of variable num: 3

Inheritance

One of the most important concepts in object-oriented programming is that of

inheritance. Inheritance allows us to define a class in terms of another class which

makes it easier to create and maintain an application. This also provides an

opportunity to reuse the code functionality and fast implementation time.

When creating a class, instead of writing completely new data members and

member functions, the programmer can designate that the new class should

inherit the members of an existing class. This existing class is called the base class,

and the new class is referred to as the derived class.

Base & Derived Classes:

A class can be derived from more than one class or interface, which means that it

can inherit data and functions from multiple base classes or interfaces.

The syntax used in VB.Net for creating derived classes is as follows:

<access-specifier> Class <base_class>

...

End Class

Class <derived_class>: Inherits <base_class>

...

End Class

Consider a base class Shape and its derived class Rectangle:

' Base class

Class Shape

Protected width As Integer

Protected height As Integer

Public Sub setWidth(ByVal w As Integer)

width = w

End Sub

Public Sub setHeight(ByVal h As Integer)

height = h

End Sub

End Class

' Derived class

Class Rectangle : Inherits Shape

Public Function getArea() As Integer

Return (width * height)

End Function

End Class

Class RectangleTester

Shared Sub Main()

Dim rect As Rectangle = New Rectangle()

rect.setWidth(5)

rect.setHeight(7)

' Print the area of the object.

Console.WriteLine("Total area: {0}", rect.getArea())

Console.ReadKey()

End Sub

End Class


Total area: 35

Base Class Initialization

The derived class inherits the base class member variables and member methods.

Therefore, the super class object should be created before the subclass is created.

The super class or the base class is implicitly known as MyBase in VB.Net

The following program demonstrates this:

' Base class

Class Rectangle

Protected width As Double

Protected length As Double

Public Sub New(ByVal l As Double, ByVal w As Double)

length = l

width = w

End Sub

Public Function GetArea() As Double

Return (width * length)

End Function

Public Overridable Sub Display()

Console.WriteLine("Length: {0}", length)

Console.WriteLine("Width: {0}", width)

Console.WriteLine("Area: {0}", GetArea())

End Sub

'end class Rectangle

End Class

'Derived class

Class Tabletop : Inherits Rectangle

Private cost As Double

Public Sub New(ByVal l As Double, ByVal w As Double)

MyBase.New(l, w)

End Sub

Public Function GetCost() As Double

Dim cost As Double

cost = GetArea() * 70

Return cost

End Function

Public Overrides Sub Display()

MyBase.Display()

Console.WriteLine("Cost: {0}", GetCost())

End Sub

'end class Tabletop

End Class

Class RectangleTester

Shared Sub Main()

Dim t As Tabletop = New Tabletop(4.5, 7.5)

t.Display()

Console.ReadKey()

End Sub

End Class


Length: 4.5

Width: 7.5

Area: 33.75

Cost: 2362.5

UNIT-7 Namespaces

Namespaces-: Namespaces help you to create logical groups of related classes

and interfaces. Namespaces allow us to organize Classes so that they can be easily

accessed in other applications. Namespace is logical division of class, structure

and interface or way to organize your Visual Basic .NET code is through the use of

namespaces. They are a way of grouping type names and reducing the chance of

name collisions. The namespace with all the built-in functionality comes under

System namespace.

Collections of function method lasses’ data types are known as

name space. There are thousands of base classes are organized in much the same

way. a file system is organized into folder. These unit in which vb.net classes are

organized are classes are called name space.name space are control to the .net

environment as they provide a mechanism by which classes can be organized into

logical grouping making them easier to find and manage.name space in vb.net

are declared using a block structure name space.

Unit 8 Exception Handling

An exception is a problem that arises during the execution of a program. An

exception is a response to an exceptional circumstance that arises while a

program is running, such as an attempt to divide by zero. Exceptions provide a

way to transfer control from one part of a program to another. VB.Net

exception handling is built upon four keywords: Try, Catch, Finally and Throw.

Try: A Try block identifies a block of code for which particular exceptions

will be activated.

It’s follo ed y o e or ore Cat h lo ks. Catch: A program catches an exception with an exception handler at the

place in a program

where you want to handle the problem. The Catch keyword indicates the

catching of an exception.

Finally: The Finally block is used to execute a given set of statements,

whether an exception

is thrown or not thrown. For example, if you open a file, it must be closed

whether an exception is raised or not.

Throw: A program throws an exception when a problem shows up. This is

done using a Throw keyword.

Exception Classes in vb.Net Framework-: In the .Net Framework, exceptions are

represented by classes. The exception classes in .Net Framework 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.

The System.ApplicationException class supports exceptions generated by

application programs. So the exceptions defined by the programmers should

derive from this class.

The System.SystemException class is the base class for all predefined system

exception.

The following table provides some of the predefined exception classes derived

from the Sytem.SystemException class:

Exception Class Description

System.IO.IOException Handles I/O errors.

System.IndexOutOfRangeException Handles errors generated when a method

refers to an array index out of range.

System.ArrayTypeMismatchException Handles errors generated when type is

mismatched with the array type.

System.NullReferenceException Handles errors generated from deferencing

a null object.

System.DivideByZeroException Handles errors generated from dividing a

dividend with zero.

System.InvalidCastException Handles errors generated during

typecasting.

System.OutOfMemoryException Handles errors generated from insufficient

free memory.

System.StackOverflowException Handles errors generated from stack

overflow.

Handling Exceptions

VB.Net provides a structured solution to the exception handling problems in the

form of try and catch blocks. Using these blocks the core program statements are

separated from the error-handling statements.

These error handling blocks are implemented using the Try, Catch and Finally

keywords. Following is an example of throwing an exception when dividing by

zero condition occurs:

Module exceptionProg

Sub division(ByVal num1 As Integer, ByVal num2 As Integer)

Dim result As Integer

Try

result = num1 \ num2

Catch e As DivideByZeroException

Console.WriteLine("Exception caught: {0}", e)

Finally

Console.WriteLine("Result: {0}", result)

End Try

End Sub

Sub Main()

division(25, 0)

Console.ReadKey()

End Sub

End Module


Exception caught: System.DivideByZeroException: Attempted to divide by zero.

at ...

Result: 0

Creating User-Defined Exceptions

You can also define your own exception. User-defined exception classes are

derived from the ApplicationException class. The following example

demonstrates this:


Public Class TempIsZeroException : Inherits ApplicationException

Public Sub New(ByVal message As String)

MyBase.New(message)

End Sub

End Class

Public Class Temperature

Dim temperature As Integer = 0

Sub showTemp()

If (temperature = 0) Then

Throw (New TempIsZeroException("Zero Temperature found"))

Else

Console.WriteLine("Temperature: {0}", temperature)

End If

End Sub

End Class

Sub Main()

Dim temp As Temperature = New Temperature()

Try

temp.showTemp()

Catch e As TempIsZeroException

Console.WriteLine("TempIsZeroException: {0}", e.Message)

End Try

Console.ReadKey()

End Sub

End Module


TempIsZeroException: Zero Temperature found

Throwing Objects

You can throw an object if it is either directly or indirectly derived from the

System.Exception class.

You can use a throw statement in the catch block to throw the present object as:

Throw [ expression ]

The following program demonstrates this:


Sub Main()

Try

Throw New ApplicationException("A custom exception _

is being thrown here...")

Catch e As Exception

Console.WriteLine(e.Message)

Finally

Console.WriteLine("Now inside the Finally Block")

End Try

Console.ReadKey()

End Sub

End Module


A custom exception is being thrown here...

Now inside the Finally Block

Unit 9 Using System.Collections

ArrayList-: An array stores a fixed-size sequential collection of elements of the

same type. An array is used to store a collection of data, but it is often more

useful to think of an array as a collection of variables of the same type.

All arrays consist of contiguous memory locations. The lowest address

corresponds to the first element and the highest address to the last element.

The elements in an array can be stored and accessed by using the index of the

array. The following program demonstrates this:

Module arrayApl

Sub Main()

Dim n(10) As Integer ' n is an array of 11 integers '

Dim i, j As Integer

' initialize elements of array n '

For i = 0 To 10

n(i) = i + 100 ' set element at location i to i + 100

Next i

' output each array element's value '

For j = 0 To 10

Console.WriteLine("Element({0}) = {1}", j, n(j))

Next j

Console.ReadKey()

End Sub

End Module

Properties and Methods Used in ArrayList-:

Some common methods are:

1. Public Overridable Function Add (value As Object) As Integer: Adds an object

to the end of the ArrayList.

2. Public Overridable Sub AddRange (c As ICollection): Adds the elements of an

ICollection to the end of the ArrayList.

3. Public Overridable Sub Clear: Removes all elements from the ArrayList.

4. Public Overridable Function Contains (item As Object) As Boolean: Determines

whether an element is in the Array List.

5. Public Overridable Function GetRange (index As Integer, count As Integer) As

ArrayList: Returns an ArrayList which represents a subset of the elements in the

source ArrayList.

6. Public Overridable Function IndexOf (value As Object) As Integer: Returns the

zero-based index of the first occurrence of a value in the ArrayList or in a portion

of it.

7. Public Overridable Sub Insert (index As Integer, value As Object): Inserts an

element into the ArrayList at the specified index.

8. Public Overridable Sub InsertRange (index As Integer, c As ICollection):Inserts

the elements of a collection into the ArrayList at the specified index.

9. Public Overridable Sub Remove (obj As Object):Removes the first occurrence

of a specific object from the ArrayList.

10. Public Overridable Sub RemoveAt (index As Integer):Removes the element at

the specified index of the ArrayList.

Unit 10

Windows Programming

Q1 What is window form?

Ans-:Windows Forms is a framework located in the System.Windows.Forms.dll

assembly for building Windows applications in .NET based on a Graphical User

Interface (GUI). Any language that supports the Common Language Runtime (CLR)

can use Windows Forms. If you have programmed in Visual Basic (VB), you are

probably familiar with forms. In VB, all windows are forms. Controls are placed on

forms to develop GUI applications.

In addition, Windows Forms applications provide the following:

Simple and flexible property support

Common control support, including support for font and color dialogs

Support for Web Services

Data-aware controls using ADO.NET

ActiveX support

GDI+ (Graphical Device Interface +), a better and richer graphics library,

which supports

alpha blending, texture brushes, advanced transformations, and rich text

Metadata support

Q2Explain the controls in vb.net?

Ans-:The Control Class defines the base class for controls, which are components

with visual representation.

Control Tab Order-: Using the Tab key we can move focus from one control to

other. We can also customize this tab order. For this we make use of the Tab

Index property.there are many controls in vb.net.

1.Button Control-: The Button control represents a standard Windows

button. It is generally used to generate a Click event by providing a handler for the

Click event.

1. AutoSizeMode Gets or sets the mode by which the Button automatically

resizes itself.

2. BackColor Gets or sets the background color of the control.

3. BackgroundImage Gets or sets the background image displayed in the control.

4. DialogResult Gets or sets a value that is returned to the parent form when the

button is clicked. This is used while creating dialog boxes.

5. ForeColor Gets or sets the foreground color of the control.

6. Image Gets or sets the image that is displayed on a button control.

7. Location Gets or sets the coordination of the upper-left corner of the control

relative to the upper-left corner of its container.

8. TabIndex Gets or sets the tab order of the control within container.

2.TextBox Control-: The TextBoxcontrol in Visual Basic 6.0 is replaced by the

Windows Forms TextBox control in Visual Basic .NET. The names of some

properties, methods, events, and constantszare different, and in some cases there

are differences in behavior. The following tables list Visual Basic 6.0 properties,

methods, and events and their Visual Basic .NET equivalents. Where applicable,

constants are indented beneath the property or method. All Visual Basic .NET

constants map to the System.Windows.Formsnamespace unless otherwise noted.

Text box controls allow entering text on a form at runtime.

TextBox Properties-:

1. AutoCompleteSource -: Gets or sets a value specifying the source of complete

strings used for automatic completion.

2.CharacterCasing -: Gets or sets whether the TextBox control modifies the case

of characters as they are typed.

3.Font -: Gets or sets the font of the text displayed by the control.

4.FontHeight-: Gets or sets the height of the font of the control.

5.Forecolor -: Gets or sets the foreground color of the control.

6.Lines -: Gets or sets the lines of text in a text box control.

7.Multiline-: Gets or sets a value indicating whether this is a multiline TextBox

control.

8.ScrollBars-: Gets or sets which scroll bars should appear in a multiline TextBox

control.

This property has values:

None

Horizontal

Vertical

Both

9.TabIndex-: Gets or sets the tab order of the control within its container.

10.Text-: Gets or sets the current text in the TextBox.

11.TextAlign-: Gets or sets how text is aligned in a TextBox control.

This property has values:

Left

Right

Center

3. RichTextBox Control-: A RichTextBox control is an advanced text box

that provides text editing and advanced formatting features including loading Rich

Text Format (RTF) files.We can create a RichTextBox control using a Forms

designer at design-time or using the RichTextBox class in code at run-time. To

create a RichTextBox control at design-time, you simply drag and drop a

RichTextBox control from Toolbox onto a Form in Visual Studio.

4.CheckBox Control-: CheckBoxes allow the user to make multiple

selections from a number of options. You can click a checkBox to select it and click

it again to deselect it.

5. ListBox-: The ListBox control displays a list of items from which we can

make a selection. We can select one or more than one of the items from the list.

Properties of list box-:

1. AllowSelection- Gets a value indicating whether the ListBox currently enables

selection of list items.

2. BorderStyle -Gets or sets the type of border drawn around the list box.

3. ColumnWidth -Gets of sets the width of columns in a multicolumn list box.

4. HorizontalExtent -Gets or sets the horizontal scrolling area of a list box.

6. ItemHeight -Gets or sets the height of an item in the list box.

7. Items - Gets the items of the list box.

8. MultiColumn - Gets or sets a value indicating whether the list box supports

multiple columns.

6. ComboBox-: The ComboBox control is used to display a drop-down list of

various items. It is a combination of a text box in which the user enters an item

and a drop-down list from which the user selects an item.

7. TreeView-: TreeView control is used to display hierarchical tree like

information such as a directory hierarchy.The top level in a tree view are root

nodes that can be expanded or collapsed if the nodes have child nodes

8. CheckedListBox-: A CheckedListBox control is a ListBox control with

CheckBox displayed in the left side where user can select a single or multiple

items. We can create a CheckedListBox control using a Forms designer at design-

time or using the CheckedListBox class in code at run-time (also known as

dynamically).

9.Panel-: The Panel control is a container control that is used to host a group of

similar child controls.

10. GroupBox-: Group Box is a container of other control. It displays a frame

around a group of controls. When you move the Group Box control, all of its

contained will also move.

GroupBox Properties

Auto Size: Gets or sets a value that indicates whether the GroupBox resizes

based on its contents.

BackColor: Gets or sets the background color for the control.

ForeColor:Change Fore Color of all control in side Group Box]

11. PictureBox Control-:

PictureBox control is used to display image. The images displayed can be any

format like Bitmap, JPEG, and GIF, PNG or any other image format files. The

PictureBox control is based on

the Control class.

12. StatusBar-: StatusBar control is not available in Toolbox of Visual Studio

2010. StatusStrip control replaces StatusBar in Visual Studio 2010. But for

backward compatibility support, StatusBar class is available in Windows Forms.

A StatusBar control is a combination of StatusBar panels where each panel can be

used to display different information.

13. RadioButton-: A radio button or option button is a type of graphical user

interface element that allows the user to choose only one of a predefined set of

options. When a user clicks on a radio button, it becomes checked, and all other

radio buttons with same group become unchecked.

Unit 11

Common Dialog Boxes

Common Dialog Boxes-: There are many built-in dialog boxes to be used in

Windows forms for various tasks like opening and saving files, printing a page,

providing choices for colors, fonts, page setup, etc., to the user of an application.

These built-in dialog boxes reduce the developer's time and workload.

All of these dialog box control classes inherit from the CommonDialog class and

override the RunDialog() function of the base class to create the specific dialog

box.

The RunDialog() function is automatically invoked when a user of a dialog box

calls its ShowDialog() function.

The ShowDialog method is used to display all the dialog box controls at run-time.

It returns a value of the type of DialogResult enumeration. The values of

DialogResult enumeration are:

Abort - returns DialogResult.Abort value, when user clicks an Abort button.

Cancel- returns DialogResult.Cancel, when user clicks a Cancel button.

Ignore - returns DialogResult.Ignore, when user clicks an Ignore button.

No - returns DialogResult.No, when user clicks a No button.

None - returns nothing and the dialog box continues running.

OK - returns DialogResult.OK, when user clicks an OK button

Retry - returns DialogResult.Retry , when user clicks an Retry button

Yes - returns DialogResult.Yes, when user clicks an Yes button

Unit 12 Q1 what is file and stream?

Ans-:a file is a collection of data and a

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