WAP to Display Message in VB

8/22/2019 WAP to Display Message in VB

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http://www.tutorialspoint.com/vb.net/vb.net_decision_

making.htm

The following reasons make VB.Net a widely usedprofessional language:

Modern, general purpose.

Object oriented.

Component oriented.(GUI)

Easy to learn.

Structured language.

It produces efficient programs.

It can be compiled on a variety of computerplatforms.

Part of .Net Framework.

Strong Programming Features VB.Net

VB.Net has numerous strong programming features

that make it endearing to multitude of programmers

worldwide. Let us mention some of these features:

Boolean Conditions

Automatic Garbage Collection(to removeunnecessary condition)
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Standard Library(namespace)

Assembly Versioning(

runtime of .NET programe is called Assembly

1.private----one person(mail)

2.sharedmore than on person(internet))

Properties and Events

Delegates and Events Management

Easy to use Generics

Indexers

Conditional Compilation

Simple Multithreading

The .Net framework is a revolutionary

platform that helps you to write

the following types of applications:

Windows applications Web applications

Web services


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The .Net framework applications are multi-platformapplications. The framework has been designed insuch a way that it can be used from any of the

following languages: Visual Basic, C#, C++, Jscript,and COBOL etc.

All these languages can access the framework aswell as communicate with each other.

The .Net framework consists of an enormous libraryof codes used by the client languages like VB.Net.These languages use object oriented methodology.

Following are some of the components of the .Netframework:

Common Language Runtime (CLR)

The .Net Framework Class Library

Common Language Specification

Common Type System

Metadata and Assemblies

Windows Forms

ASP.Net and ASP.Net AJAX

ADO.Net

Windows Workflow Foundation (WF)


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Windows Presentation Foundation

Windows Communication Foundation (WCF)

LINQFor the jobs each of these components perform,please see ASP.Net - Introductionand for details ofeach component, please consult Microsoft'sdocumentation.

Integrated Development Environment (IDE) For

VB.Net

Microsoft provides the following development toolsfor VB.Net programming:

Visual Studio 2010 (VS)

Visual Basic 2010 Express (VBE)

Visual Web Developer

The last two are free. Using these tools you canwrite all kinds of VB.Net programs from simplecommand-line applications to more complexapplications.

VB.Net Hello World ExampleA VB.Net program basically consists of the followingparts:

Namespace declaration
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A class or module

One or more procedures

Variables The Main procedure

Statements & Expressions

Comments

Imports System

Module Module1 'This program will display HelloWorld

Sub Main() Console.WriteLine("HelloWorld")

Console.ReadKey()//Console.ReadLine()

EndSub EndModule

When we consider a VB.Net program it can be

defined as a collection of objects that communicatevia invoking each other's methods. Let us now brieflylook into what do class, object, methods and instantvariables mean.


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Object - Objects have states and behaviors.Example: A dog has states-color, name, breed aswell as behaviors -wagging, barking, eating etc. An

object is an instance of a class. Class - A class can be defined as a template/ blue

print that describe the behaviors/states that object ofits type support.

Methods - A method is basically a behavior. A classcan contain many methods. It is in methods wherethe logics are written, data is manipulated and all theactions are executed.

Instant Variables - Each object has its unique set ofinstant variables. An object's state is created by thevalues assigned to these instant variables.

Imports System PublicClass Rectangle Private length AsDouble Private width AsDouble 'Public methods PublicSub AcceptDetails() length =4.5 width =3.5 EndSub PublicFunction GetArea()AsDouble

GetArea = length * width


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

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

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

EndSub SharedSub Main() Dim r AsNew Rectangle() r.Acceptdetails() r.Display() Console.ReadLine()

EndSub EndClass

Comments:It is nothing but the

description of a program.It is not a

compulasory and doesnt effect source

code or programe

It is denoted by

WAP to display message in VB.Net


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Module Module1Sub Main()

Console.WriteLine("hai")

Console.Read()EndSub

EndModule

Variables:It is used to vary the

values or changes values in a program.

1.to declare variablenameDim variablename As datatype

//datatype varname;ex:int a; C#

Ex:

Dim a As Integer

Dim s As String

2.to declare more than one variable

with same datatype

Dim varname1,varname2,.As datatype

//datatype varname1,varname2,. //inta,b;

Ex:

Dim a,b As Integer


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3.To declare variablename with value

Dim variablename As datatype=value

Dim a As Integer=10

To display no and name by using

variablrs:

Module Module1Dim a AsInteger = 10Dim b AsString = "ravi"Sub Main()

Console.WriteLine("no is" & a)

Console.WriteLine("name is" &b)& concat operator


EndModuleOrModule Module1

Dim a AsIntegerDim b AsStringSub Main()


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a = CInt(Console.ReadLine())b = Console.ReadLine()Console.WriteLine("no is" & a)

Console.WriteLine("name is" &b)


EndModule

Constants:

Declaring Constants

In VB.Net, constants are declared usingthe Const statement. The Const statement is usedat module, class, structure, procedure, or block levelfor use in place of literal values.

The syntax for the Const statement is:

[< attributelist>][ accessmodifier][Shadows]Const constantlist

Const a As Integer=value//constants

Ex:const a As Integer=10

Dim a As Integer//variables

Where,


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attr ibutel ist : specifies the list of attributes applied tothe constants; you can provide multiple attributes,separated by commas. Optional.

accessmodif ier : specifies which code can accessthese constants. Optional. Values can be either ofthe: Public, Protected, Friend, Protected Friend, orPrivate.

Shadows: this makes the constant hide aprogramming element of identical name, in a baseclass. Optional.

Constant l ist : gives the list of names of constantsdeclared. Required.

Where, each constant name has the followingsyntax and parts:

constantname [As datatype ]=

initializer constantname: specifies the name of the constant datatype: specifies the data type of the constant init ial izer: specifies the value assigned to the

constant

For example,

' The following statements declareconstants.Const maxval AsLong=4999


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PublicConst message AsString="HELLO"PrivateConst piValue AsDouble=

3.1415

List of Available Modifiers in VB.Net

The following table provides the complete list ofVB.Net modifiers:

S.N Modifier Description

1 Ansi

Specifies that VisualBasic should marshal allstrings to AmericanNational StandardsInstitute (ANSI) valuesregardless of the name

of the externalprocedure beingdeclared.

2 Assembly

Specifies that anattribute at thebeginning of a sourcefile applies to the entire

assembly.

3 AsyncIndicates that themethod or lambdaexpression that it


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modifies isasynchronous. Suchmethods are referred to

as async methods. Thecaller of an asyncmethod can resume itswork without waiting forthe async method tofinish..

4 Auto

The charsetmodifierpartinthe Declare statementsupplies the characterset information formarshaling stringsduring a call to the

external procedure. Italso affects how VisualBasic searches theexternal file for theexternal procedurename. The Auto

modifier specifies thatVisual Basic shouldmarshal stringsaccording to .NETFramework rules.


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5 ByRef

Specifies that anargument is passed byreference, i.e., the

called procedure canchange the value of avariable underlying theargument in the callingcode. It is used underthe contexts of:

Declare StatementFunction StatementSub Statement

6 ByVal

Specifies that anargument is passed insuch a way that thecalled procedure or

property cannot changethe value of a variableunderlying the argumentin the calling code. It isused under the contextsof:

Declare Statementunction StatementOperator StatementProperty StatementSub Statement


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7 Default

Identifies a property asthe default property ofits class, structure, or

interface.

8 Friend

Specifies that one ormore declaredprogramming elementsare accessible fromwithin the assembly that

contains theirdeclaration, not only bythe component thatdeclares them.Friend access is oftenthe preferred level foran application's

programming elements,and Friend is the defaultaccess level of aninterface, a module, aclass, or a structure.

9 In

It is used in generic

interfaces anddelegates.

10 IteratorSpecifies that a functionor Get accessor is an


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iterator.An iteratorperforms acustom iteration over a

collection.

11 Key

The Key keywordenables you to specifybehavior for propertiesof anonymous types.

12 Module

Specifies that an

attribute at thebeginning of a sourcefile applies to thecurrent assemblymodule. It is not sameas the Module

statement.

13 MustInherit

Specifies that a classcan be used only as abase class and that youcannot create an objectdirectly from it.

14 MustOverride

Specifies that a propertyor procedure is notimplemented in thisclass and must beoverridden in a derived


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class before it can beused.

15 Narrowing

Indicates that aconversion operator(CType) converts aclass or structure to atype that might not beable to hold some of thepossible values of the

original class orstructure.

16 NotInheritableSpecifies that a classcannot be used as abase class.

17 NotOverridable

Specifies that a property

or procedure cannot beoverridden in a derivedclass.

18 Optional

Specifies that aprocedure argumentcan be omitted when

the procedure is called.

19 Out

For generic typeparameters, the Outkeyword specifies thatthe type is covariant.


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20 Overloads

Specifies that a propertyor procedure redeclaresone or more existing

properties orprocedures with thesame name.

21 Overridable

Specifies that a propertyor procedure can beoverridden by an

identically namedproperty or procedure ina derived class.

22 Overrides

Specifies that a propertyor procedure overridesan identically named

property or procedureinherited from a baseclass.

23 ParamArray

ParamArray allows youto pass an arbitrarynumber of arguments tothe procedure. A

ParamArray parameteris always declared usingByVal.

24 Partial Indicates that a class or


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structure declaration isa partial definition of theclass or structure.

25 Private

Specifies that one ormore declaredprogramming elementsare accessible only fromwithin their declarationcontext, including from

within any containedtypes.

26 Protected

Specifies that one ormore declaredprogramming elementsare accessible only from

within their own class orfrom a derived class.

27 Public

Specifies that one ormore declaredprogramming elementshave no accessrestrictions.

28 ReadOnlySpecifies that a variableor property can be readbut not written.

29 Shadows Specifies that a


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declared programmingelement redeclares andhides an identically

named element, or setof overloaded elements,in a base class.

30 Shared

Specifies that one ormore declaredprogramming elements

are associated with aclass or structure atlarge, and not with aspecific instance of theclass or structure.

31 Static

Specifies that one or

more declared localvariables are tocontinue to exist andretain their latest valuesafter termination of theprocedure in which theyare declared.

32 Unicode

Specifies that VisualBasic should marshal allstrings to Unicodevalues regardless of the


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name of the externalprocedure beingdeclared.

33 Widening

Indicates that aconversion operator(CType) converts aclass or structure to atype that can hold allpossible values of the

original class orstructure.

34 WithEvents

Specifies that one ormore declared membervariables refer to aninstance of a class that

can raise events.

35 WriteOnlySpecifies that a propertycan be written but notread.

A statement is a complete instruction in VisualBasic programs. It may contain keywords, operators,variables, literal values, constants and expressions.

Statements could be categorized as:


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Declaration statements - these are the statementswhere you name a variable, constant, or procedure,and can also specify a data type.

Executable statements - these are the statements,which initiate actions. These statements can call amethod or function, loop or branch through blocks ofcode or assign values or expression to a variable orconstant. In the last case, it is called an Assignmentstatement.

Declaration Statements

The declaration statements are used to name anddefine procedures, variables, properties, arrays, andconstants. When you declare a programmingelement, you can also define its data type, accesslevel, and scope.

The programming elements you may declare includevariables, constants, enumerations, classes,structures, modules, interfaces, procedures,procedure parameters, function returns, externalprocedure references, operators, properties, events,and delegates.

Following are the declaration statements in VB.Net:

S.NStatementsandDescription

Example


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1

DimStatementDeclares

andallocatesstoragespace forone or morevariables.

Dim number As

IntegerDim quantity AsInteger = 100Dim message AsString = "Hello!"

2

ConstStatementDeclaresand definesone or moreconstants.

Const maximum AsLong = 1000ConstnaturalLogBase AsObject=CDec(2.7182818284)

3

EnumStatementDeclares anenumerationand definesthe values of

its members.

Enum CoffeeMugSizeJumboExtraLargeLargeMediumSmall

End Enum

4ClassStatementDeclares the

Class BoxPublic length AsDouble


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name of aclass andintroduces

the definitionof thevariables,properties,events, andprocedures

that theclasscomprises.

Public breadth AsDoublePublic height As

DoubleEnd Class

5

StructureStatementDeclares thename of a

structureandintroducesthe definitionof thevariables,

properties,events, andproceduresthat thestructure

Structure BoxPublic length AsDoublePublic breadth AsDoublePublic height AsDouble

End Structure


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comprises.

6

ModuleStatementDeclares thename of amodule andintroducesthe definitionof the

variables,properties,events, andproceduresthat themodulecomprises.

Public ModulemyModuleSub Main()Dim user As String=InputBox("What is

your name?")MsgBox("User nameis" & user)End SubEnd Module

7

InterfaceStatementDeclares thename of aninterfaceand

introducesthedefinitions ofthemembers

Public InterfaceMyInterface

Sub

doSomething()End Interface


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that theinterfacecomprises.

8

FunctionStatementDeclares thename,parameters,and code

that define aFunctionprocedure.

FunctionmyFunction(ByVal n AsInteger) As Double

Return 5.87 *

nEnd Function

9

SubStatementDeclares the

name,parameters,and codethat define aSubprocedure.

Sub mySub(ByVal s

As String)Return

End Sub

10

Declare

StatementDeclares areference toa procedure

Declare Function

getUserNameLib "advapi32.dll"Alias"GetUserNameA"


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implementedin anexternal file.

(ByVal lpBuffer

As String,

ByRef nSize AsInteger) AsInteger

11

OperatorStatementDeclares the

operatorsymbol,operands,and codethat definean operatorprocedure

on a class orstructure.

Public SharedOperator +(ByVal x As obj,ByVal y As obj) Asobj

Dim r AsNew obj' implementioncode for r = x + y

Return rEnd Operator

12

PropertyStatementDeclares thename of a

property,and thepropertyproceduresused to

ReadOnly Propertyquote() As String

Get

ReturnquoteString

End GetEnd Property


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store andretrieve thevalue of the

property.

13

EventStatementDeclares auser-definedevent.

Public EventFinished()

14

DelegateStatementUsed todeclare adelegate.

Delegate FunctionMathOperator(

ByVal x AsDouble,

ByVal y AsDouble) As Double

Executable Statements

An executable statement performs an action.Statements calling a procedure, branching toanother place in the code, looping through severalstatements, or evaluating an expression areexecutable statements. An assignment statement isa special case of an executable statement.

Datatypes:


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Data Types Available in VB.Net

VB.Net provides a wide range of data types. Thefollowing table shows all the data types available:

DataType

StorageAllocation

Value Range

Boole

an

Dependson

implementingplatform

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 onDecember 31, 9999

Decimal

16 bytes

0 through +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9...E+28)with nodecimal point; 0 through +/-

7.9228162514264337593543950335 with 28 places to the right ofthe decimal

Doubl 8 bytes -1.79769313486231570E+308


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e through -4.94065645841246544E-324, fornegative values

4.94065645841246544E-324through1.79769313486231570E+308,for positive values

Intege

r

4 bytes-2,147,483,648 through

2,147,483,647 (signed)

Long 8 bytes

-9,223,372,036,854,775,808through9,223,372,036,854,775,807(signed)

Object

4 bytes on

32-bitplatform

8 bytes on64-bitplatform

Any type can be stored in avariable 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


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values;

1.401298E-45 through

3.4028235E+38 for positivevalues

String

Dependsonimplementing

platform

0 to approximately 2 billionUnicode characters

UInteger

4 bytes0 through 4,294,967,295(unsigned)

ULong 8 bytes0 through18,446,744,073,709,551,615(unsigned)

User-Defined

Dependsonimplementingplatform

Each member of the structurehas a range determined by itsdata type and independent of theranges of the other members

UShor

t2 bytes 0 through 65,535 (unsigned)

Example

The following example demonstrates use of some ofthe types:


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Module DataTypesSub Main()

Dim b AsByte

Dim n AsIntegerDim si AsSingleDim d AsDoubleDim da AsDateDim c AsCharDim s AsStringDim bl AsBooleanb =1n =1234567si =0.12345678901234566d =0.12345678901234566da = Todayc ="U"c

s ="Me"If ScriptEngine ="VB"Thenbl =True

Elsebl =False

EndIfIf bl Then

'the oath takingConsole.Write(c &" and,"&

s & vbCrLf)Console.WriteLine("declaring

on the day of: {0}", da)


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Console.WriteLine("We willlearn VB.Net seriously")

Console.WriteLine("Lets see

what happens to the floating pointvariables:")

Console.WriteLine("TheSingle: {0}, The Double: {1}", si, d)

EndIfConsole.ReadKey()

EndSub

EndModule

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

U and, Me

declaring on the day of: 12/4/201212:00:00 PMWe will learn VB.Net seriouslyLets see what happens to the floatingpoint variables:The Single:0.1234568, The Double:0.123456789012346

The Type Conversion Functions in VB.Net

VB.Net provides the following inline type conversionfunctions:


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S.N Functionss & Description

1CBool(expression)Converts the expression to Booleandata type.

2CByte(expression)Converts the expression to Byte datatype.

3

CChar(expression)

Converts the expression to Char datatype.

4CDate(expression)Converts the expression to Date datatype

5

CDbl(expression)

Converts the expression to Doubledata type.

6CDec(expression)Converts the expression to Decimaldata type.

7

CInt(expression)

Converts the expression to Integerdata type.

8CLng(expression)Converts the expression to Long datatype.


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9CObj(expression)Converts the expression to Objecttype.

10CSByte(expression)Converts the expression to SBytedata type.

11CShort(expression)Converts the expression to Shortdata type.

12CSng(expression)Converts the expression to Singledata type.

13CStr(expression)Converts the expression to Stringdata type.

14CUInt(expression)Converts the expression to UInt datatype.

15CULng(expression)Converts the expression to ULngdata type.

16CUShort(expression)Converts the expression to UShortdata type.

Example:


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The following example demonstrates some of thesefunctions:

Module DataTypesSub Main()Dim n AsIntegerDim da AsDateDim bl AsBoolean=Truen =1234567da = Today

Console.WriteLine(bl)Console.WriteLine(CSByte(bl))Console.WriteLine(CStr(bl))Console.WriteLine(CStr(da))

Console.WriteLine(CChar(CChar(CStr(n))))

Console.WriteLine(CChar(CStr(da)))Console.ReadKey()

EndSubEndModule

When the above code is compiled and executed, it

produces following result:

True-1True


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12/4/201211

Variable Declaration in VB.Net

The Dim statement is used for variable declarationand storage allocation for one or more variables.The Dim statement is used at module, class,structure, procedure or block level.

Syntax for variable declaration in VB.Net is:

[< attributelist>][ accessmodifier][[Shared][Shadows]|[Static]][ReadOnly]Dim[WithEvents]variablelist

Where, attr ibutel ist is a list of attributes that apply to the

variable. Optional. accessmodif ier defines the access levels of the

variables, it has values as - Public, Protected,Friend, Protected Friend and Private. Optional.

Shareddeclares a shared variable, which is notassociated with any specific instance of a class orstructure, rather available to all the instances of theclass or structure. Optional.


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Shadows indicate that the variable re-declares andhides an identically named element, or set ofoverloaded elements, in a base class. Optional.

Static indicates that the variable will retain its value,even when the after termination of the procedure inwhich it is declared. Optional.

ReadOnlymeans the variable can be read, but notwritten. Optional.

WithEventsspecifies that the variable is used torespond to events raised by the instance assigned tothe variable. Optional.

Variablel ist provides the list of variables declared.

Operators:

An operator is a symbol that tells the compiler toperform specific mathematical or logicalmanipulations. VB.Net is rich in built-in operatorsand provides following type of commonly usedoperators:

Arithmetic Operators

Comparison Operators

Logical/Bitwise Operators

Bit Shift Operators


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Assignment Operators

Miscellaneous Operators

Arithmetic Operators Following table shows all the arithmetic

operators supported by VB.Net. Assumevariable A holds 2 and variable B holds 7 then:

Show ExamplesOperator Description Example

^Raises one operandto the power ofanother

B^A willgive 49

+ Adds two operandsA + Bwill give9

- Subtracts secondoperand from the first

A - B willgive -5

*Multiply bothoperands

A * B willgive 14

/

Divide one operandby another and

returns a floatingpoint result

B / A will

give 3.5

\Divide one operandby another and

B \ A willgive 3
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returns an integerresult

MOD

Modulus Operatorand remainder ofafter an integerdivision

B MODA willgive 1

Comparison Operators

Following table shows all the comparison operatorssupported by VB.Net. Assume variable A holds 10

and variable B holds 20 then:Show Examples

Operator Description Example

==

Checks if the value oftwo operands isequal or not, if yes

then conditionbecomes true.

(A == B)is not

true.

Checks if the value oftwo operands isequal or not, if valuesare not equal then

condition becomestrue.

(A B)is true.

>Checks if the value ofleft operand is

(A > B)is not
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greater than thevalue of rightoperand, if yes then

condition becomestrue.

true.

=

Checks if the value ofleft operand isgreater than or equalto the value of right

operand, if yes thencondition becomestrue.

(A >= B)is not

true.


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VB.Net provides three more comparison operators,which we will be using in forthcoming chapters;however, we give a brief description here.

Is Operator - It compares two object referencevariables and determines if two object referencesrefer to the same object without performing valuecomparisons. If object1 and object2 both refer to theexact same object instance, result is True;otherwise, result is False.

IsNot Operator - It also compares two objectreference variables and determines if two objectreferences refer to different objects. If object1 andobject2 both refer to the exact same object instance,result is False; otherwise, result is True.

Like Operator - It compares a string against apattern.

Logical/Bitwise Operators Following table shows all the logical operators

supported by VB.Net. Assume variable A holds

Boolean value True and variable B holds Boolean

value False then:

Show Examples


And

It is the logical as well as

bitwise AND operator. If

both the operands are

(A And

B) is

False.
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true then condition

becomes true. This

operator does not

perform short-circuiting,i.e., it evaluates both the

expressions.

Or

It is the logical as well as

bitwise OR operator. If

any of the two operands

is true then conditionbecomes true. This

operator does not

perform short-circuiting,

i.e., it evaluates both the

expressions.

(A Or B)

is True.

Not

It is the logical as well asbitwise NOT operator.

Use to reverses the

logical state of its

operand. If a condition istrue then Logical NOT

operator will make false.

Not(A

And B)

is True.

Xor

It is the logical as well asbitwise Logical

Exclusive OR operator.

It returns True if both

A Xor B

is True.


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expressions are True or

both expressions are

False; otherwise it

returns False. Thisoperator does not

perform short-circuiting,

it always evaluates both

expressions and there is

no short-circuiting

counterpart of thisoperator

AndAlso

It is the logical AND

operator. It works only

on Boolean data. It

performs short-

circuiting.

(A

AndAlso

B) is

False.

OrElse

It is the logical OR

operator. It works only

on Boolean data. It

performs short-circuiting.

(A

OrElse

B) is

True.

IsFalse

It determines whether an

expression is False.

IsTrueIt determines whetheran expression is True.


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Bit Shift Operators

We have already discussed the bitwise operators.The bit shift operators perform the shift operationson binary values. Before coming into the bit shiftoperators, let us understand the bit operations.

Bitwise operators work on bits and perform bit by bitoperation. The truth tables for &, |, and ^ are asfollows:

p q p & q p | q p ^ q0 0 0 0 0

0 1 0 1 1

1 1 1 1 0

1 0 0 1 1

Assume if A = 60; and B = 13; Now in binary formatthey will be as follows:

A = 0011 1100

B = 0000 1101

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

A&B = 0000 1100

A|B = 0011 1101

A^B = 0011 0001


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~A = 1100 0011

We have seen that the Bitwise operators supportedby VB.Net are And, Or, Xor and Not. The Bit shiftoperators are >> and


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Not

Binary OnesComplementOperator is unary

and has the effect of'flipping' bits.

(Not A )will give -60 which

is 11000011

Binary Right ShiftOperator. The leftoperands value is

moved right by thenumber of bitsspecified by the rightoperand.

A >> 2will give

15 whichis 00001111

Assignment Operators

There are following assignment operators supported

by VB.Net:Show Examples


= Simple assignment C = A + B
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operator, Assignsvalues from rightside operands to left

side operand

will assignvalue of A+ B into C

+=

Add ANDassignmentoperator, It addsright operand to theleft operand and

assign the result toleft operand

C += A isequivalentto C = C +A

-=

Subtract ANDassignmentoperator, It subtractsright operand from

the left operand andassign the result toleft operand

C -= A isequivalentto C = C -

A

*=

Multiply ANDassignmentoperator, Itmultiplies right

operand with the leftoperand and assignthe result to leftoperand

C *= A isequivalent

to C = C *A


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/=

Divide ANDassignmentoperator, It divides

left operand with theright operand andassign the result toleft operand(floatingpoint division)

C /= A is

equivalentto C = C /A

\=

Divide AND

assignmentoperator, It dividesleft operand with theright operand andassign the result toleft operand (Integerdivision)

C \= A isequivalentto C = C\A

^=

Exponentiation andassignmentoperator. It raisesthe left operand tothe power of theright operand and

assigns the result toleft operand.

C^=A isequivalentto C = C ^A


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as C = C>=Right shift ANDassignment operator

C >>= 2is sameas C = C>> 2

&=

Concatenates aString expression toa String variable or

property andassigns the result tothe variable orproperty.

Str1 &=Str2 is

same asStr1 =Str1 &Str2

Miscellaneous Operators

There are few other important operators supported

by VB.Net.

Show Examples

Operator

Description

Example

AddressOf

Returns

theaddressof aprocedure.

AddHandlerButton1.Click,AddressOf Button1_Click
http://www.tutorialspoint.com/vb.net/vb.net_misc_operators.htmhttp://www.tutorialspoint.com/vb.net/vb.net_misc_operators.htm


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Await

It isapplied toan

operandin anasynchronousmethodor

lambdaexpression tosuspendexecutionof themethod

until theawaitedtaskcompletes.

Dim result As res

= AwaitAsyncMethodThatReturnsResult()Await AsyncMethod()

GetType

It returns

a Typeobject forthespecifiedtype. The

MsgBox(GetType(Integer).ToString())


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Typeobjectprovides

information aboutthe typesuch asitspropertie

s,methods,andevents.

FunctionExpression

Itdeclaresthe

parameters andcode thatdefine afunctionlambda

expression.

Dim add5 = Function(numAsInteger) num + 5

'prints 10Console.WriteLine(add5(5))

IfIt usesshort-circuit

Dim num = 5Console.WriteLine(If(num>= 0,


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evaluation tocondition

ally returnone oftwovalues.The Ifoperator

can becalledwith threearguments or withtwoargument

s.

"Positive", "Negative"))

Operators Precedence in VB.Net

Operator Precedence

Await Highest

Exponentiation (^)

Unary identity and negation(+, -)

Multiplication and floating-point division (*, /)


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Integer division (\)

Modulus arithmetic (Mod)

Addition and subtraction (+,-)

Arithmetic bit shift ()

All comparison operators (=,, =, Is, IsNot,Like, TypeOf...Is)

Negation (Not)

Conjunction (And, AndAlso)

Inclusive disjunction (Or,OrElse)

Exclusive disjunction (Xor) Lowest

Decision making statements:

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

t is the simplest form of control statement, frequentlyused in decision making and changing the control

flow of the program execution. Syntax for if-thenstatement is:

If condition Then[Statement(s)]


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EndIf

If(boolean_expression)Then'statement(s) will execute if the

Boolean expression is trueElse'statement(s) will execute if the

Boolean expression is falseEndIf

It is always legal in VB.Net to nest If-Then-Elsestatements, which means you can use one If or

ElseIf statement inside another If ElseIfstatement(s).

Syntax:

The syntax for a nested If statement is as follows:

If( boolean_expression 1)Then

'Executes when the booleanexpression 1 is true

If(boolean_expression 2)Then'Executes when the boolean

expression 2 is true


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EndIfEndIf

A Select Case statement allows a variable to betested for equality against a list of values. Eachvalue is called a case, and the variable beingswitched on is checked for each select case.

Syntax:

The syntax for a Select Case statement in VB.Net isas follows:

Select[Case] expression[Case expressionlist

[ statements ]][CaseElse

[ elsestatements ]]EndSelect

Module decisionsSub Main()

'local variable definition

Dim grade AsChargrade ="B"Select grade

Case"A"


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Console.WriteLine("Excellent!")

Case"B","C"

Console.WriteLine("Welldone")

Case"D"Console.WriteLine("You

passed")Case"F"

Console.WriteLine("Better try again")CaseElse

Console.WriteLine("Invalid grade")EndSelectConsole.WriteLine("Your grade is

{0}", grade)Console.ReadLine()EndSub

EndModule

Looping:

It repeats the enclosed block of statements while aBoolean condition is True or until the conditionbecomes True. It could be terminated at any timewith the Exit Do statement.


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The syntax for this loop construct is:

Tutorial content goes here.....

Do{While|Until} condition[ statements ][ Continue Do][ statements ][ExitDo][ statements ]

Loop-or-Do

[ statements ][ Continue Do][ statements ][ExitDo]

[ statements ]Loop{While|Until} conditionModule loops

Sub Main()' local variable definitionDim a AsInteger=10'do loop execution

DoConsole.WriteLine("value of

a: {0}", a)a = a +1

LoopWhile(a


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Console.ReadLine()EndSub

EndModule


value of a: 10value of a: 11value of a: 12

value of a: 13value of a: 14value of a: 15value of a: 16value of a: 17value of a: 18value of a: 19

The program would behave in same way, if you usean Until statement, instead of While:

Module loopsSub Main()

' local variable definitionDim a AsInteger=10'do loop executionDo

Console.WriteLine("value ofa: {0}", a)


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a = a +1LoopUntil(a =20)Console.ReadLine()

EndSubEndModule


value of a: 10

value of a: 11value of a: 12value of a: 13value of a: 14value of a: 15value of a: 16value of a: 17

value of a: 18value of a: 19

It repeats a group of statements a specified numberof times and a loop index counts the number of loopiterations as the loop executes.

The syntax for this loop construct is:

For counter [As datatype ]= start Toend[Stepstep]

[ statements ][ Continue For]


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[ statements ][ExitFor][ statements ]

Next[ counter ]

Example

Module loopsSub Main()

Dim a AsByte

' for loop executionFor a =10To20

Console.WriteLine("value ofa: {0}", a)

NextConsole.ReadLine()

EndSub

EndModule


value of a: 10value of a: 11

value of a: 12value of a: 13value of a: 14value of a: 15value of a: 16


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value of a: 17value of a: 18value of a: 19

value of a: 20

Date and Time functions:

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

The Date data type contains date values, time

values, or date and time values. The default value ofDate is 0:00:00 (midnight) on January 1, 0001. The

equivalent .NET data type is System.DateTime.

Properties and Methods of the DateTime Structure

The following table lists some of the commonlyused properties of the DateTime Structure:

S.N Property Description

1 DateGets the date component of this

instance.

2 Day

Gets the day of the month

represented by this instance.

3 DayOfWeekGets the day of the week



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4 DayOfYearGets the day of the year


5 Hour

Gets the hour component of the

date represented by this

instance.

6 Kind

Gets a value that indicates

whether the time represented by

this instance is based on local

time, Coordinated Universal Time

(UTC), or neither.

7 Millisecond

Gets the milliseconds component

of the date represented by this

instance.

8 Minute

Gets the minute component of

the date represented by this

instance.

9 MonthGets the month component of thedate represented by this

instance.


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10 Now

Gets a DateTime object that is

set to the current date and time

on this computer, expressed as

the local time.

11 Second

Gets the seconds component of

the date represented by this

instance.

12 Ticks

Gets the number of ticks that

represent the date and time of

this instance.

13 TimeOfDayGets the time of day for this

instance.

14 Today Gets the current date.

15 UtcNow

Gets a DateTime object that is

set to the current date and time

on this computer, expressed as

the Coordinated Universal Time(UTC).

16 Year Gets the year component of the


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date represented by this

instance.

The following table lists some of the commonlyused methods of the DateTime structure:

S.N Method Name & Description

1

Public Function Add ( value As TimeSpan )

As DateTime

Returns a new DateTime that adds the value ofthe specified TimeSpan to the value of this

instance.

2

Public Function AddDays ( value As Double

) As DateTime

Returns a new DateTime that adds thespecified number of days to the value of this

instance.

3

Public Function AddHours ( value As

Double ) As DateTime

Returns a new DateTime that adds thespecified number of hours to the value of this

instance.


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4

Public Function AddMinutes ( value As


Returns a new DateTime that adds the

specified number of minutes to the value of this

instance.

5

Public Function AddMonths ( months As

Integer ) As DateTime


specified number of months to the value of this

instance.

6

Public Function AddSeconds ( value As



specified number of seconds to the value of

this instance.

7

Public Function AddYears ( value As

Integer ) As DateTime


specified number of years to the value of this

instance.


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8

Public Shared Function Compare ( t1 As

DateTime, t2 As DateTime ) As Integer

Compares two instances of DateTime and

returns an integer that indicates whether the

first instance is earlier than, the same as, or

later than the second instance.

9

Public Function CompareTo ( value As

DateTime ) As Integer

Compares the value of this instance to a

specified DateTime value and returns an

integer that indicates whether this instance is

earlier than, the same as, or later than the

specified DateTime value.

10

Public Function Equals ( value As DateTime

) As Boolean

Returns a value indicating whether the value of

this instance is equal to the value of the

specified DateTime instance.

11Public Shared Function Equals ( t1 As

DateTime, t2 As DateTime ) As Boolean

Returns a value indicating whether two


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DateTime instances have the same date and

time value.

12

Public Overrides Function ToString As

String

Converts the value of the current DateTime

object to its equivalent string representation.

The above list of methods is not exhaustive, please

visitMicrosoft documentation for the complete list ofmethods and properties of the DateTime structure.

Creating a DateTime Object

You can create a DateTime object, in one of thefollowing ways:

By calling a DateTime constructor from any of theoverloaded DateTime constructors.

By assigning the DateTime object a date and timevalue returned by a property or method.

By parsing the string representation of a date andtime value.

By calling the DateTime structure's implicit defaultconstructor.

The following example demonstrates this:
http://msdn.microsoft.com/en-us/library/system.datetime.aspxhttp://msdn.microsoft.com/en-us/library/system.datetime.aspxhttp://msdn.microsoft.com/en-us/library/system.datetime.aspx


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'DateTime constructor:

parameters year, month, day, hour,min, sec

Dim date1 AsNewDate(2012,12,16,12,0,0)

'initializes a new DateTimevalue

Dim date2 AsDate=#12/16/201212:00:52 AM#

'using propertiesDim date3 AsDate=Date.NowDim date4 AsDate=Date.UtcNowDim date5 AsDate=Date.TodayConsole.WriteLine(date1)

Console.WriteLine(date2)Console.WriteLine(date3)Console.WriteLine(date4)Console.WriteLine(date5)Console.ReadKey()

EndSubEndModule

When the above code was compiled and executed,it produced following result:

12/16/2012 12:00:00 PM


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12/16/2012 12:00:52 PM12/12/2012 10:22:50 PM12/12/2012 12:00:00 PM

Getting the Current Date and Time:

The following programs demonstrate how to get thecurrent date and time in VB.Net:

Current Time:

Module dateNtimeSub Main()

Console.Write("Current Time: ")

Console.WriteLine(Now.ToLongTimeString)

Console.ReadKey()

EndSubEndModule


Current Time: 11 :05 :32 AM

Current Date:



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Console.WriteLine("Current Date:")

Dim dt AsDate= Today

Console.WriteLine("Today is:{0}", dt)

Console.ReadKey()EndSub

EndModule

When the above code is compiled and executed, it

produces following result:

Today is: 12/11/2012 12:00:00 AM

Formatting Date

A Date literal should be enclosed within hash signs(# #), and specified in the format M/d/yyyy, for

example #12/16/2012#. Otherwise, your code maychange depending on the locale in which yourapplication is running.

For example, you specified Date literal of#2/6/2012# for the date February 6, 2012. It is alrightfor the locale that uses mm/dd/yyyy format.

However, in a locale that uses dd/mm/yyyy format,your literal would compile to June 2, 2012. If a localeuses another format say, yyyy/mm/dd, the literalwould be invalid and cause a compiler error.


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To convert a Date literal to the format of your locale,or to a custom format, use the Format function ofString class, specifying either a predefined or user-

defined date format.

The following example demonstrates this.


Console.WriteLine("India WinsFreedom: ")

Dim independenceDay AsNewDate(1947,8,15,0,0,0)

' Use format specifiers tocontrol the date display.

Console.WriteLine(" Format 'd:'"& independenceDay.ToString("d"))

Console.WriteLine(" Format 'D:'"& independenceDay.ToString("D"))Console.WriteLine(" Format 't:'

"& independenceDay.ToString("t"))Console.WriteLine(" Format 'T:'

"& independenceDay.ToString("T"))Console.WriteLine(" Format 'f:'

"& independenceDay.ToString("f"))Console.WriteLine(" Format 'F:'

"& independenceDay.ToString("F"))Console.WriteLine(" Format 'g:'

"& independenceDay.ToString("g"))


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Console.WriteLine(" Format 'G:'"& independenceDay.ToString("G"))

Console.WriteLine(" Format 'M:'

"& independenceDay.ToString("M"))Console.WriteLine(" Format 'R:'

"& independenceDay.ToString("R"))Console.WriteLine(" Format 'y:'

"& independenceDay.ToString("y"))Console.ReadKey()

EndSubEndModule

Predefined Date/Time Formats

The following table identifies the predefined dateand time format names. These may be used by

name as the style argument for the Format function:Format Description

General Date, or G

Displays a date

and/or time. For

example,

1/12/2012 07:07:30AM.

Long Date,Medium Date, or D Displays a date


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according to your

current culture's

long date format.

For example,

Sunday, December

16, 2012.

Short Date, or d

Displays a date

using your current

culture's short date

format. For

example,

12/12/2012.

Long Time,Medium Time, orT

Displays a time

using your current

culture's long time

format; typically

includes hours,

minutes, seconds.

For example,01:07:30 AM.

Short Time or t Displays a time


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using your current

culture's short time

format. For

example, 11:07

AM.

f

Displays the long

date and short time

according to your

current culture's

format. For

example, Sunday,

December 16,

2012 12:15 AM.

F

Displays the long

date and long time

according to your

current culture's

format. For

example, Sunday,December 16,

2012 12:15:31 AM.


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g

Displays the short

date and short time

according to your

current culture's

format. For

example,

12/16/2012 12:15

AM.

M, m

Displays the month

and the day of a

date. For example,

December 16.

R, r

Formats the date

according to the

RFC1123Pattern

property.

s

Formats the date

and time as a

sortable index. For

example, 2012-12-

16T12:07:31.


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u

Formats the date

and time as a GMT

sortable index. For

example, 2012-12-

16 12:15:31Z.

U

Formats the date

and time with the

long date and long

time as GMT. For

example, Sunday,

December 16,

2012 6:07:31 PM.

Y, y

Formats the date

as the year and

month. For

example,

December, 2012.

For other formats like, user defined formats, please

consultMicrosoft Documentation.Properties and Methods of the DateAndTime Class

The following table lists some of the commonlyused properties of the DateAndTime Class:
http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.strings.format.aspxhttp://msdn.microsoft.com/en-us/library/microsoft.visualbasic.strings.format.aspxhttp://msdn.microsoft.com/en-us/library/microsoft.visualbasic.strings.format.aspx


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S.N Property Description

1 Date

Returns or sets a String value

representing the current date

according to your system.

2 Now

Returns a Date value containing

the current date and time


3 TimeOfDay

Returns or sets a Date value

containing the current time of day


4 Timer

Returns a Double value

representing the number ofseconds elapsed since midnight.

5 TimeString

Returns or sets a String value

representing the current time of

day according to your system.

6 Today Gets the current date.

The following table lists some of the commonlyused methods of the DateAndTime class:


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S.N Method Name & Description

1

Public Shared Function DateAdd ( Interval

As DateInterval, Number As Double,

DateValue As DateTime ) As DateTime

Returns a Date value containing a date and

time value to which a specified time interval

has been added.

2

Public Shared Function DateAdd ( Interval

As String, Number As Double, DateValue

As Object ) As DateTime

Returns a Date value containing a date and

time value to which a specified time interval

has been added.

3

Public Shared Function DateDiff ( Interval

As DateInterval, Date1 As DateTime, Date2

As DateTime, DayOfWeek As

FirstDayOfWeek, WeekOfYear As

FirstWeekOfYear ) As Long

Returns a Long value specifying the number of

time intervals between two Date values.


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4

Public Shared Function DatePart ( Interval

As DateInterval, DateValue As DateTime,

FirstDayOfWeekValue As FirstDayOfWeek,FirstWeekOfYearValue As FirstWeekOfYear

) As Integer

Returns an Integer value containing the

specified component of a given Date value.

5

Public Shared Function Day ( DateValue As


Returns an Integer value from 1 through 31

representing the day of the month.

6

Public Shared Function Hour ( TimeValue

As DateTime ) As Integer


representing the hour of the day.

7

Public Shared Function Minute ( TimeValue



representing the minute of the hour.

8 Public Shared Function Month ( DateValue



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representing the month of the year.

9

Public Shared Function MonthName (

Month As Integer, Abbreviate As Boolean )

As String

Returns a String value containing the name of

the specified month.

10

Public Shared Function Second (

TimeValue As DateTime ) As Integer


representing the second of the minute.

11

Public Overridable Function ToString As

StringReturns a string that represents the current

object.

12

Public Shared Function Weekday (

DateValue As DateTime, DayOfWeek As

FirstDayOfWeek ) As IntegerReturns an Integer value containing a number

representing the day of the week.


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13

Public Shared Function WeekdayName (

Weekday As Integer, Abbreviate As

Boolean, FirstDayOfWeekValue AsFirstDayOfWeek ) As String

Returns a String value containing the name of

the specified weekday.

14

Public Shared Function Year ( DateValue As



representing the year.

The above list is not exhaustive. For complete list ofproperties and methods of the DateAndTime class,please consultMicrosoft Documentation.The

following program demonstrates some of these andmethods:


Dim birthday AsDateDim bday AsIntegerDim month AsIntegerDim monthname AsString' Assign a date using standard

short format.birthday =#7/27/1998#
http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.dateandtime.aspxhttp://msdn.microsoft.com/en-us/library/microsoft.visualbasic.dateandtime.aspxhttp://msdn.microsoft.com/en-us/library/microsoft.visualbasic.dateandtime.aspx


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bday =Microsoft.VisualBasic.DateAndTime.Day(birthday)

month =Microsoft.VisualBasic.DateAndTime.Month(birthday)

monthname =Microsoft.VisualBasic.DateAndTime.MonthName(month)

Console.WriteLine(birthday)Console.WriteLine(bday)Console.WriteLine(month)Console.WriteLine(monthname)Console.ReadKey()

EndSubEndModule

An array stores a fixed-size sequential collection ofelements of the same type. An array is used to storea collection of data, but it is often more useful tothink of an array as a collection of variables of thesame type.

All arrays consist of contiguous memory locations.

The lowest address corresponds to the first elementand the highest address to the last element.


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Creating Arrays in VB.Net

To declare an array in VB.Net, you use the Dimstatement. For example,

Dim intData(30) ' an array of 31elements

Dim strData(20)AsString ' an arrayof 21 stringsDim twoDarray(10,20)AsInteger 'atwo dimensional array of integersDim ranges(10,100)'a two dimensionalarray

You can also initialize the array elements whiledeclaring the array. For example,

Dim intData()AsInteger={12,16,20,24,28,32}Dim names()AsString={"Karthik","Sandhya", _

"Shivangi","Ashwitha","Somnath"}Dim miscData()AsObject={"HelloWorld",12d,16ui,"A"c}


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The elements in an array can be stored andaccessed by using the index of the array. Thefollowing program demonstrates this:

Module arrayAplSub Main()

Dim n(10)AsInteger ' n is anarray of 11 integers '

Dim i, j AsInteger' initialize elements of array n

'For i =0To10

n(i)= i +100' set elementat location i to i + 100

Next i' output each array element's

value '

For j =0To10

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

Next jConsole.ReadKey()

EndSubEndModule



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Element(0) = 100Element(1) = 101Element(2) = 102

Element(3) = 103Element(4) = 104Element(5) = 105Element(6) = 106Element(7) = 107Element(8) = 108Element(9) = 109Element(10) = 110

Dynamic Arrays

Dynamic arrays are arrays that can be dimensionedand re-dimensioned as par the need of the program.You can declare a dynamic array usingthe ReDim statement.

Syntax for ReDim statement:

ReDim [Preserve] arrayname(subscripts)

Where,

The Preserve keyword helps to preserve the data in

an existing array, when you resize it. arrayname is the name of the array to re-dimension subscripts specifies the new dimension.Module arrayApl

Sub Main()


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Dim marks()AsIntegerReDim marks(2)marks(0)=85

marks(1)=75marks(2)=90ReDimPreserve marks(10)marks(3)=80marks(4)=76marks(5)=92marks(6)=99marks(7)=79marks(8)=75For i =0To10

Console.WriteLine(i & vbTab& marks(i))

Next i

Console.ReadKey()EndSubEndModule


0 851 752 903 804 76


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5 926 997 79

8 759 010 0

Multi-Dimensional Arrays

VB.Net allows multidimensional arrays. Multi-dimensional arrays are also called rectangular array.

You can declare a 2 dimensional array of strings as:

Dim twoDStringArray(10,20)AsString

or, a three dimensional array of Integer variables:

Dim threeDIntArray(10,10,10)As

Integer

The following program demonstrates creating andusing a two dimensional array:

Module arrayAplSub Main()

' an array with 5 rows and 2columns

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

Dim i, j AsInteger


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' output each array element'svalue '

For i =0To4

For j =0To1

Console.WriteLine("a[{0},{1}] = {2}",i, j, a(i, j))

Next jNext iConsole.ReadKey()

EndSubEndModule


a[0,0]: 0

a[0,1]: 0a[1,0]: 1a[1,1]: 2a[2,0]: 2a[2,1]: 4a[3,0]: 3a[3,1]: 6a[4,0]: 4a[4,1]: 8

Jagged Array


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A Jagged array is an array of arrays. The follwoingcode shows declaring a jagged arraynamed scoresof Integers:

Dim scores AsInteger()()=NewInteger(5)(){}

The following example illustrates using a jaggedarray:

Module arrayApl

Sub Main()'a jagged array of 5 array of

integersDim a AsInteger()()=New

Integer(4)(){}a(0)=NewInteger(){0,0}a(1)=NewInteger(){1,2}

a(2)=NewInteger(){2,4}a(3)=NewInteger(){3,6}a(4)=NewInteger(){4,8}Dim i, j AsInteger' output each array element's

valueFor i =0To4

For j =0To1

Console.WriteLine("a[{0},{1}] = {2}",i, j, a(i)(j))


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Next jNext iConsole.ReadKey()

EndSubEndModule


a[0][0]: 0

a[0][1]: 0a[1][0]: 1a[1][1]: 2a[2][0]: 2a[2][1]: 4a[3][0]: 3a[3][1]: 6

a[4][0]: 4a[4][1]: 8

The Array Class

The Array class is the base class for all the arrays inVB.Net. It is defined in the System namespace. TheArray class provides various properties and methods

to work with arrays.

Properties of the Array Class

The following table provides some of the mostcommonly used properties of the Array class:


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S.N Property Name & Description

1

IsFixedSize

Gets a value indicating whether the Array hasa fixed size.

2IsReadOnlyGets a value indicating whether the Array isread-only.

3

Length

Gets a 32-bit integer that represents the totalnumber of elements in all the dimensions ofthe Array.

4

LongLengthGets a 64-bit integer that represents the totalnumber of elements in all the dimensions ofthe Array.

5RankGets the rank (number of dimensions) of theArray.

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

1Public Shared Sub Clear ( array As Array,index As Integer, length As Integer )


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

2

Public Shared Sub Copy ( sourceArray AsArray, destinationArray As Array, length AsInteger )Copies a range of elements from an Arraystarting at the first element and pastes theminto another Array starting at the first element.

The length is specified as a 32-bit integer.

3

Public Sub CopyTo ( array As Array, indexAs 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 specifiedas a 32-bit integer.

4

Public Function GetLength ( dimension AsInteger ) As IntegerGets a 32-bit integer that represents thenumber of elements in the specified dimensionof the Array.

5

Public Function GetLongLength (dimension As Integer ) As LongGets a 64-bit integer that represents thenumber of elements in the specified dimension


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of the Array.

6

Public Function GetLowerBound (

dimension As Integer ) As IntegerGets the lower bound of the specifieddimension in the Array.

7Public Function GetType As TypeGets the Type of the current instance.(Inherited from Object.)

8Public Function GetUpperBound (dimension As Integer ) As IntegerGets the upper bound of the specifieddimension in the Array.

9

Public Function GetValue ( index As Integer) As ObjectGets the value at the specified position in theone-dimensional Array. The index is specifiedas a 32-bit integer.

10

Public Shared Function IndexOf ( array AsArray, value As Object ) As IntegerSearches for the specified object and returnsthe index of the first occurrence within the

entire one-dimensional Array.

11Public Shared Sub Reverse ( array As Array)Reverses the sequence of the elements in the


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entire one-dimensional Array.

12

Public Sub SetValue ( value As Object,

index As Integer )Sets a value to the element at the specifiedposition in the one-dimensional Array. Theindex 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 IComparableimplementation of each element of the Array.

14

Public Overridable Function ToString AsStringeturns a string that represents the currentobject. (Inherited from Object.)

For complete list of Array class properties andmethods, please consult Microsoft documentation.

Example

The following program demonstrates use of some ofthe methods of the Array class:

Module arrayAplSub Main()Dim list AsInteger()={34,72,

13,44,25,30,10}Dim temp AsInteger()= list


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Dim i AsIntegerConsole.Write("Original Array:

")

ForEach i In listConsole.Write("{0} ", i)

Next iConsole.WriteLine()' reverse the arrayArray.Reverse(temp)Console.Write("Reversed Array:

")ForEach i In temp

Console.Write("{0} ", i)Next iConsole.WriteLine()'sort the array

Array.Sort(list)Console.Write("Sorted Array: ")ForEach i In list

Console.Write("{0} ", i)Next iConsole.WriteLine()Console.ReadKey()

EndSubEndModule



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Original Array: 34 72 13 44 25 30 10Reversed Array: 10 30 25 44 13 72 34Sorted Array: 10 13 25 30 34 44 72

Various Collection Classes and Their Usage

The following are the various commonly usedclasses of the System.Collection namespace. Clickthe following links to check their detail.

Class Description and Useage

ArrayList

It represents ordered collection of anobject that can be indexed individually.It is basically an alternative to an array.However unlike array you can add andremove items from a list at a specifiedposition using an index and the arrayresizes itself automatically. It also allowsdynamic memory allocation, add, searchand sort items in the list.

Hashtable

It uses a key to access the elements inthe collection.A hash table is used when you need toaccess elements by using key, and you

can identify a useful key value. Eachitem in the hash table hasa key/value pair. The key is used toaccess the items in the collection.
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SortedList

It uses a key as well as an index toaccess the items in a list.

A sorted list is a combination of an arrayand a hash table. It contains a list ofitems that can be accessed using a keyor an index. If you access items using anindex, it is an ArrayList, and if youaccess items using a key, it is aHashtable. The collection of items is

always sorted by the key value.

Stack

It represents a last-in, firstout 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 theitem and when you remove it, it is

calledpopping the item.

Queue

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 anitem in the list, it is called enqueue andwhen you remove an item, it iscalleddeque.
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BitArray

It represents an array of the binaryrepresentation using the values 1 and0.

It is used when you need to store thebits 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.

A procedure is a group of statements that togetherperform a task, when called. After the procedure isexecuted, the control returns to the statement callingthe procedure. VB.Net has two types of procedures:

Functions

Sub procedures or Subs

Functions return a value, where Subs do not return avalue.

Defining a FunctionThe Function statement is used to declare the name,parameter and the body of a function. The syntax forthe Function statement is:
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[Modifiers] Function FunctionName[(ParameterList)]As ReturnType

[Statements]

EndFunction

Where,

Tutorial content goes here.....

Modif iers: specifiy the access level of the function;possible values are: Public, Private, Protected,

Friend, Protected Friend and information regardingoverloading, overriding, sharing, and shadowing.

Funct ionName: indicates the name of the function ParameterList : specifies the list of the parameters ReturnType: specifies the data type of the variable

the function returns

ExampleFollowing code snippet shows afunction FindMax that takes two integer values andreturns the larger of the two.

Function FindMax(ByVal num1 AsInteger,ByVal num2 AsInteger)AsInteger

' local variable declaration */Dim result AsIntegerIf(num1 > num2)Then

result = num1Else


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result = num2EndIfFindMax = result

EndFunction

Function Returning a Value

In VB.Net a function can return a value to the callingcode in two ways:

By using the return statement

By assigning the value to the function nameThe following example demonstrates usingthe FindMax function:

Module myfunctionsFunction FindMax(ByVal num1 As

Integer,ByVal num2 AsInteger)AsInteger

' local variable declaration */Dim result AsIntegerIf(num1 > num2)Then

result = num1Else

result = num2EndIfFindMax = result

EndFunctionSub Main()


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Dim a AsInteger=100Dim b AsInteger=200Dim res AsInteger

res = FindMax(a, b)Console.WriteLine("Max value is

: {0}", res)Console.ReadLine()

EndSubEndModule


Max value is : 200

Recursive Function

A function can call itself. This is known as recursion.

Following is an example that calculates factorial fora given number using a recursive function:

Module myfunctionsFunction factorial(ByVal num As

Integer)AsInteger' local variable declaration */

Dim result AsIntegerIf(num =1)Then

Return1Else


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result = factorial(num -1)* num

Return result

EndIfEndFunctionSub Main()

'calling the factorial methodConsole.WriteLine("Factorial of

6 is : {0}", factorial(6))Console.WriteLine("Factorial of

7 is : {0}", factorial(7))Console.WriteLine("Factorial of

8 is : {0}", factorial(8))Console.ReadLine()

EndSubEndModule


Factorial of 6 is: 720Factorial of 7 is: 5040Factorial of 8 is: 40320

Param ArraysAt times, while declaring a function or sub procedureyou are not sure of the number of arguments passedas a parameter. VB.Net param arrays (or parameterarrays) come into help at these times.


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The following example demonstrates this:

Module myparamfunc

Function AddElements(ParamArray arrAsInteger())AsIntegerDim sum AsInteger=0Dim i AsInteger=0ForEach i In arr

sum += iNext i

Return sumEndFunctionSub Main()

Dim sum AsIntegersum = AddElements(512,720,250,

567,889)Console.WriteLine("The sum is:

{0}", sum)Console.ReadLine()

EndSubEndModule


The sum is: 2938

Passing Arrays as Function Arguments


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You can pass an array as a function argument inVB.Net. The following example demonstrates this:

Module arrayParameterFunction getAverage(ByVal arr AsInteger(),ByVal size AsInteger)AsDouble

'local variablesDim i AsIntegerDim avg AsDouble

Dim sum AsInteger=0For i =0To size -1

sum += arr(i)Next iavg = sum / sizeReturn avg

EndFunction

Sub Main()' an int array with 5 elements

'Dim balance AsInteger()=

{1000,2,3,17,50}Dim avg AsDouble'pass pointer to the array as

an argumentavg = getAverage(balance,5)' output the returned value '


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Console.WriteLine("Averagevalue is: {0} ", avg)

Console.ReadLine()

EndSubEndModule


Average value is: 214.4

Defining Sub ProceduresThe Sub statement is used to declare the name,parameter and the body of a sub procedure. Thesyntax for the Sub statement is:

[Modifiers] Sub SubName[(ParameterList)]

[Statements]EndSub

Where,

Modif iers: specifiy the access level of theprocedure; possible values are: Public, Private,Protected, Friend, Protected Friend and information

regarding overloading, overriding, sharing, andshadowing.

SubName: indicates the name of the Sub ParameterList : specifies the list of the parameters


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Example

The following example demonstrates a Subprocedure CalculatePaythat takes two

parameters hoursand wages and displays the totalpay of an employee:

Module mysubSub CalculatePay(ByVal hours As

Double,ByVal wage AsDecimal)'local variable declaration

Dim pay AsDoublepay = hours * wageConsole.WriteLine("Total Pay:

{0:C}", pay)EndSubSub Main()

'calling the CalculatePay Sub

ProcedureCalculatePay(25,10)CalculatePay(40,20)CalculatePay(30,27.5)Console.ReadLine()

EndSubEndModule


Total Pay: $250.00


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Total Pay: $800.00Total Pay: $825.00

Passing Parameters by Value

This is the default mechanism for passingparameters to a method. In this mechanism, when amethod is called, a new storage location is createdfor each value parameter. The values of the actualparameters are copied into them. So, the changesmade to the parameter inside the method have no

effect on the argument.

In VB.Net, you declare the reference parametersusing the ByVal keyword. The following exampledemonstrates the concept:

Module paramByvalSub swap(ByVal x AsInteger,ByVal

y AsInteger)Dim temp AsIntegertemp = x ' save the value of xx = y ' put y into xy = temp 'put temp into y

EndSub

Sub Main()' local variable definitionDim a AsInteger=100Dim b AsInteger=200


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Console.WriteLine("Before swap,value of a : {0}", a)

Console.WriteLine("Before swap,

value of b : {0}", b)' calling a function to swap the

values 'swap(a, b)Console.WriteLine("After swap,

value of a : {0}", a)Console.WriteLine("After swap,

value of b : {0}", b)Console.ReadLine()

EndSubEndModule


Before swap, value of a :100Before swap, value of b :200After swap, value of a :100After swap, value of b :200

It shows that there is no change in the values though

they had been changed inside the function.

Passing Parameters by Reference

A reference parameter is a reference to a memorylocation of a variable. When you pass parameters by


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reference, unlike value parameters, a new storagelocation is not created for these parameters. Thereference parameters represent the same memory

location as the actual parameters that are suppliedto the method.

In VB.Net, you declare the reference parametersusing the ByRef keyword. The following exampledemonstrates this:

Module paramByref

Sub swap(ByRef x AsInteger,ByRefy AsInteger)

Dim temp AsIntegertemp = x ' save the value of xx = y ' put y into xy = temp 'put temp into y

EndSubSub Main()

' local variable definitionDim a AsInteger=100Dim b AsInteger=200Console.WriteLine("Before swap,

value of a : {0}", a)

Console.WriteLine("Before swap,value of b : {0}", b)' calling a function to swap the

values 'swap(a, b)


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Console.WriteLine("After swap,value of a : {0}", a)

Console.WriteLine("After swap,

value of b : {0}", b)Console.ReadLine()

EndSubEndModule


Before swap, value of a : 100Before swap, value of b : 200After swap, value of a : 200After swap, value of b : 100

Class Definition

A class definition starts with thekeyword Class followed by the class name; and theclass body, ended by the End Class statement.Following is the general form of a class definition:

[][ accessmodifier ][Shadows][MustInherit|NotInheritable][ Partial ] _

Class name [( Of typelist )][Inherits classname ][Implements interfacenames ][ statements ]

EndClass


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Where,

attr ibutel ist is a list of attributes that apply to theclass. Optional.

accessmodif ier defines the access levels of theclass, it has values as - Public, Protected, Friend,Protected Friend and Private. Optional.

Shadows indicate that the variable re-declares andhides an identically named element, or set ofoverloaded elements, in a base class. Optional.

MustInheri t specifies that the class can be usedonly as a base class and that you cannot create anobject directly from it, i.e, an abstract class. Optional.

NotInheri tablespecifies that the class cannot beused as a base class.

Partial indicates a partial definition of the class Inheri tsspecifies the base class it is inheriting from Implementsspecifies the interfaces the class is

inheriting from

The following example demonstrates a Box class,with three data members, length, breadth andheight:

Module myboxClass BoxPublic length AsDouble '

Length of a box


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Public breadth AsDouble 'Breadth of a box

Public height AsDouble '

Height of a boxEndClassSub Main()

Dim Box1 As Box =New Box()' Declare Box1 of type Box


Dim volume AsDouble=0.0 'Store the volume of a box here

' box 1 specificationBox1.height =5.0Box1.length =6.0Box1.breadth =7.0

' box 2 specificationBox2.height =10.0Box2.length =12.0Box2.breadth =13.0'volume of box 1volume = Box1.height *

Box1.length * Box1.breadth

Console.WriteLine("Volume ofBox1 : {0}", volume)

'volume of box 2volume = Box2.height *

Box2.length * Box2.breadth


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Console.WriteLine("Volume ofBox2 : {0}", volume)

Console.ReadKey()

EndSubEndModule


Volume of Box1 : 210

Volume of Box2 : 1560Member Functions and Encapsulation

A member function of a class is a function that hasits definition or its prototype within the classdefinition like any other variable. It operates on anyobject 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 (fromdesign perspective) and they are kept private toimplement encapsulation. These variables can onlybe accessed using the public member functions.

Let us put above concepts to set and get the value

of different class members in a class:

Module myboxClass Box


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Public length AsDouble 'Length of a box

Public breadth AsDouble '

Breadth of a boxPublic height AsDouble '

Height of a boxPublicSub setLength(ByVal len

AsDouble)length = len

EndSubPublicSub setBreadth(ByVal bre

AsDouble)breadth = bre

EndSubPublicSub setHeight(ByVal hei

AsDouble)

height = heiEndSubPublicFunction getVolume()As

DoubleReturn length * breadth *

heightEndFunction

EndClassSub Main()



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Dim volume AsDouble=0.0 '

Store the volume of a box here

' box 1 specificationBox1.setLength(6.0)Box1.setBreadth(7.0)Box1.setHeight(5.0)

'box 2 specificationBox2.setLength(12.0)Box2.setBreadth(13.0)Box2.setHeight(10.0)

' volume of box 1

volume = Box1.getVolume()Console.WriteLine("Volume ofBox1 : {0}", volume)

'volume of box 2volume = Box2.getVolume()Console.WriteLine("Volume of

Box2 : {0}", volume)Console.ReadKey()

EndSubEndModule


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Volume of Box1 : 210Volume of Box2 : 1560

Constructors and Destructors

A class constructor is a special member Sub of aclass that is executed whenever we create newobjects of that class. A constructor has thename New and it does not have any return type.

Following program explain the concept ofconstructor:

Class LinePrivate length AsDouble '

Length of a line

PublicSubNew() 'constructorConsole.WriteLine("Object is

being created")EndSubPublicSub setLength(ByVal len As

Double)length = len

EndSub

PublicFunction getLength()AsDouble

Return length


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EndFunctionSharedSub Main()

Dim line As Line =New Line()

'set line lengthline.setLength(6.0)Console.WriteLine("Length of

line : {0}", line.getLength())Console.ReadKey()

EndSubEndClass


Object is being createdLength of line : 6

A default constructor does not have any parameter

but if you need a constructor can have parameters.Such constructors are called parameterizedconstructors. This technique helps you to assigninitial value to an object at the time of its creation asshown in the following example:

Class Line

Private length AsDouble 'Length of a line

PublicSubNew(ByVal len AsDouble)'parameterised constructor


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

length = len

EndSubPublicSub setLength(ByVal len As

Double)length = len

EndSub

PublicFunction getLength()AsDouble

Return lengthEndFunctionSharedSub Main()

Dim line As Line =NewLine(10.0)

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

'set line lengthline.setLength(6.0)Console.WriteLine("Length of

line set by setLength : {0}",

line.getLength())Console.ReadKey()

EndSubEndClass


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Object is being created, length = 10Length of line set by constructor : 10Length of line set by setLength : 6

A destructor is a special member Sub of a classthat is executed whenever an object of its class goesout of scope.A destructor has the name Finalize and it can

neither

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