Basic data types

 

 

Example :

Module Module1

   Sub Main()

          Dim iCount AsInteger  'declaring an integer variable

          Dim cLetter AsChar  'declaring a character variable

          Dim strName AsString  'declaring a string variable

           iCount = 10

           cLetter = "L"

           strName = "Easy Steps"

           System.Console.WriteLine(iCount) 'printing into the console

           System.Console.WriteLine(cLetter)

           System.Console.WriteLine(strName)

   EndSub

EndModule

User defined data types

Class

A class is a way to bind the data and its associated functions together. It allows the data and functions to be hidden if necessary, from external use. When defining a class we are creating a new abstract data type that can be treated like any other built in type.

Syntax :

    [Public | Protected | Friend | Protected Friend | Private] Class classname

         [Variable, Property, Method and Event Declarations]

     End Class        

Example :

Module Module1

    PublicClass Person 'declaring the class

            Dim iAge As Integer

            Dim strName As String

            PublicSub SetDetails(ByVal age AsInteger, ByVal nameAs String)

                iAge = age

                strName = name

            EndSub

            PublicSub GetDetails()

                System.Console.WriteLine(iAge)

                System.Console.WriteLine(strName)

            EndSub

     EndClass

    Sub Main()

        Dim FirstPerson AsNew Person 'creating a class variable (object)

        FirstPerson.SetDetails(27, "Erick") 'calling a member function

        FirstPerson.GetDetails()

    EndSub

EndModule

Structure

A structure associates one or more members with each other and with the structure itself. When you declare a structure, it becomes a composite data type and you can declare variables of that type.

Syntax :

[Public | Protected | Friend | Protected Friend | Private] Structure structname
     {Dim | Public | Friend | Private} member1 As datatype1
     ...
     {Dim | Public | Friend | Private} memberN As datatypeN
End Structure

Example :

Module Module1

    PublicStructure Person 'declaring the structure

        Dim iAge AsInteger

        Dim strName As String

        PublicSub SetDetails(ByVal age AsInteger, ByVal name AsString)

            iAge = age

            strName = name

        EndSub

        PublicSub GetDetails()

            System.Console.WriteLine(iAge)

            System.Console.WriteLine(strName)

        EndSub

    EndStructure

    Sub Main()

        Dim FirstPerson As New Person 'creating a structure variable

        FirstPerson.SetDetails(27, "Erick") 'calling a memberfunction

        FirstPerson.GetDetails()

    EndSub

End Module

Program execution control Statements

If...Then...Else Statements

An If...Then...Else statement is the basic conditional statement. If the expression in the If statement is True, the statements enclosed by the If block are executed. If the expression is False, each of the ElseIf expressions is evaluated.

Syntax :

If Expression [ Then ] StatementTerminator   

    [ Block ] 

[ ElseIfStatement+ ]    

    [ Block ]

[ ElseStatement ] 

     [ Block ]

End If StatementTerminator

Example :

    Module Module1

        Sub Main()

            DimiNumber AsInteger

            iNumber = System.Console.ReadLine()

            IfiNumber < 5 Then

                System.Console.WriteLine("Number is Less than Five")

            Else

                System.Console.WriteLine("Number is Greater than Five")

            EndIf

        EndSub

    EndModule

Select Case

A Select Case statement executes statements based on the value of an expression.

Syntax :

Select [ Case ] Expression StatementTerminator    

    [ CaseStatement+ ]    

            ....

    [ CaseElseStatement ]    

End Select StatementTerminator

Example :

Module Module1

        Sub Main()

            Dim x As Integer = 10

            SelectCase x

                Case 5

                    Console.WriteLine("x = 5")

                Case 10

                    Console.WriteLine("x = 10")

                Case 20

                    Console.WriteLine("x = 20 – 10")

                Case 30

                    Console.WriteLine("x = 30")

            EndSelect

        EndSub

EndModule

While Do While

A While or Do loop statement loops based on a Boolean expression. A While loop statement loops as long as the Boolean expression evaluates to True;

Syntax :

1) While Expression StatementTerminator  

                 [ Block ]   

          End While StatementTerminator

2) Do [ WhileOrUntil Expression ] StatementTerminator    [ Block ] 

                   Loop [ WhileOrUntil Expression ] StatementTerminator

Example :

Module Module1

        Sub Main()

            Dim x As Integer

            x = 3

            DoWhile x > 0

                Console.WriteLine("Do While x > 0")

                x -= 1

            Loop

            x = 3

            While x < 5

                Console.WriteLine("While x < 5")

                x += 1

            EndWhile

            Do

                Console.WriteLine("While x = 2")

                x -= 1

            LoopWhile x > 2

        EndSub

End Module

For Loop

For/Next loops enable you to evaluate a sequence of statements multiple times.

Syntax :

For [Expression]

        [Block]

Next

Example :

Module Module1

    Sub Main()

        Dim x As Integer

        For x = 1 To 10

            System.Console.WriteLine("VB Dot Net in Easy Steps")

        Next x

    EndSub

End Module

For Each Loop

A For Each...Next statement loops based on the elements in an expression. A For Each statement specifies a loop control variable and an enumerator expression.

Syntax :

    For Each LoopControlVariable In Expression StatementTerminator   

         [ Block ]  

   Next [Expression ] StatementTerminator

Example :

Module Module1

    SubMain()

        Dim x(9) As Integer

        Dim i As Integer="2"> = 0

        For i = 0 To 9

            x(i) = i + 1

        Next

        ForEach y AsInteger In x

            System.Console.WriteLine(y)

        Next

    EndSub

End Module