vb operator

8/8/2019 Vb Operator

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OPERATORSOPERATORS


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CATEGORIES OF

OPERATORS

Arithmetic Operators

Comparison Operators

Logical Operators

Concatenation Operators


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ARITHMETIC OPERATORS

Operator Mathematical Function Example

+ Addition 4 + 2

- Subtraction 4 - 3

* Multiplication 4 * 3=12

/ Division 12/4=3

Mod Modulus (returns the remainder) 15 Mod 4=3

\ Integer Division (discard decimal 19\4=4

places)

^ Exponential 2^4=16


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COMPARISION OPERATORS

Operator Meaning

= Equal to

> More than

< Less than

>= More than and equal


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LOGICAL OPERATORS

Operator Meaning

And Both condition must be true

Or One condition must be true

Not Negates Truth


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CONCATENATION OPERATOR

These operators are used to join two expressions.They are used as:

Answer= concatenation operator

Where Answer is the result of concatenation

Concatenation can be & or +.


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NOTE

In case of & operator, if an expression is not a

string, it is converted to a string before

concatenation.

In case of + operator, if both the expressions

are Variant and contain numbers, then the result

will be the sum of two numbers.

If both the expressions are Variant and contain

string values, the result will be a concatenated

string.


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CONTROLCONTROL STRUCTURESSTRUCTURES

ControlControl StructuresStructures areare thosethose programmingprogramming structuresstructures

thatthat controlcontrol thethe functioningfunctioning ofof aa programprogram.. ThereThere areare 22

typestypes ofof controlcontrol structuresstructures::--

1.1. DecisionDecision StructureStructure

2.2. LoopLoop StructureStructure


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DECISION STRUCTURESDECISION STRUCTURES

TheseThese enableenable usus toto executeexecute aa certaincertain setset of of

statementsstatements basedbased onon somesome conditioncondition whichwhich

needsneeds toto bebe specifiedspecified atat designdesign timetime andand notnot atat

runrun timetime..

AtAt runrun--time,time, thethe conditioncondition isis evaluatedevaluated andanddependingdepending onon thethe resultresult ofof text,text, thethe blockblock ofof

codecode isis executedexecuted..


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IfIf--thenthen--ElseElse StatementStatement

AA conditioncondition isis testedtested.. IfIf conditioncondition isis true,true, thenthen thethe statementsstatements

afterafter thenthen areare executedexecuted.. OtherwiseOtherwise thethe statementsstatements afterafter ElseElse

areare executedexecuted..

SyntaxSyntax:: IfIfconditioncondition thenthen

statementstatementElseElse

statementstatement

EndEnd IfIf

ExampleExample:: IfIfusername=managerusername=manager thenthenMsgBoxMsgBox truetrue

ElseElse

MsgBoxMsgBox falsefalse

EndEnd IfIf


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Nested IfNested If

Syntax:Syntax:--

IfIf conditioncondition ThenThen

statementstatement

ElseElse

IfIf conditionsconditions ThenThen

statementstatement

End IfEnd If

End IfEnd If


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IfIf--thenthen--ElseIfElseIf--Else StatementElse Statement

Syntax:Syntax:

IfIfcondition1condition1 thenthen

statement1statement1

ElseIfElseIfcondition2condition2 thenthenstatement2statement2

ElseIfElseIfcondition3condition3 thenthen

statement3statement3

ElseElsestatementstatement

End IfEnd If


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IfIf condtionscondtions11 isis true,true, thethe programprogram willwill executeexecutestatementstatement11 andand stopstop examineexamine otherother conditionsconditions..

IfIf condtioncondtion11 isis false,false, thethe programprogram willwill examineexamine

condtioncondtion22 andand actact accordinglyaccordingly..

ItIt isis possiblepossible thatthat nonenone ofof thethe statedstated conditioncondition isistruetrue.. InIn thisthis case,case, youyou shouldshould provideprovide aa ElseElse

SectionSection..

TheThe ElseElse SectionSection mustmust bebe lastlast inin thethe listlist of ofconditionsconditions andand wouldwould actact if if nonenone of of thethe primaryprimary

conditionsconditions isis truetrue..

IfIf--thenthen--ElseIfElseIf--Else StatementElse Statement


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Example ofExample of IfIf--thenthen--ElseIfElseIf--ElseElse

StatementStatement

Private Sub Form_Load()

If BackColor = vbRed Then

BackColor = vbBlueElseIf BackColor = vbBlue Then

BackColor = vbGreen

Else

BackColor = vbBlackEnd If

End Sub


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WriteWrite a Program in Visual Basic to checka Program in Visual Basic to check

greaternumber.greaternumber.

Private Sub Command1_Click()

Dim i As Integer, j As Integer

i = Text1.Text

j = Text2.Text

Ifi > j Then

MsgBox "i is Greater"

ElseMsgBox "j is Greater"

End If

End Sub


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QuestionQuestion

Write a Program in Visual Basic to check

whether a number is Even or odd.


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ProgramProgram


Dim i As Integer

i =T

ext1.T

extIfi Mod 2 = 0 Then

MsgBox "even number"

Else

MsgBox "odd number"End If

End Sub


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Select Case StatementSelect Case Statement

Another way to control the program flow, that is, theSelect Case control structure.

However, the Select Case control structure is slightlydifferent from the If....ElseIfcontrol structure .

The difference is that the Select Case control structurebasically only make decision on one expression or dimension (for example the examination grade) whilethe If ...ElseIfstatement control structure may evaluate

only one expression. Select Case is preferred when there exist many

different conditions because using If...ThenElseIfstatements might become too messy.


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Select Case StatementSelect Case Statement

ForFor multiplemultiple conditionalconditional statements,statements, itit isis betterbetter toto useuse

SelectSelect CaseCase.. TheThe formatformat isis ::

Select CaseSelect Case expressionexpression

Case expression1Case expression1

Statement1Statement1

CaseCase expression2expression2

Statement2Statement2

CaseCase expression3expression3Statement3Statement3

CaseCase ElseElse

StatementStatement

End SelectEnd Select


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Example of Select Case StatementExample of Select Case Statement

Private Sub Form_Load()

Select Case BackColor

Case vbRed

BackColor = vbBlueCase vbBlue

BackColor = vbGreen

Case vbGreen

BackColor = vbBlack

Case Else

BackColor = vbRed

End Select

End Sub


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Example of Using Select Case StatementExample of Using Select Case Statement

' Examination Grades' Examination GradesDim grade As StringDim grade As String

Private Sub Compute_Click( )Private Sub Compute_Click( )

grade = txtgrade.Textgrade = txtgrade.Text

Select Case gradeSelect Case grade

Case "A"Case "A"

result.Caption="Distinction"result.Caption="Distinction"

Case "B"Case "B"

result.Caption=First Division"result.Caption=First Division"

Case "C"Case "C"result.Caption=Second Division"result.Caption=Second Division"

Case ElseCase Else

result.Caption="Fail"result.Caption="Fail"

End SelectEnd Select

End SubEnd Sub


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LoopingLooping

The other major type of control statement is the

loop. You use loops to perform repetitive tasks

in your program.

Do Loop

While. Wend loop

For....Next Loop


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Do LoopDo Loop

Do While Loop

The keyword While in the Do While statement tells theprogram that the loop will be repeated while the conditionexpression is True. When the condition in a Do While

loop becomes false, the program moves on to the nextstatement after the Loop statement.

Do Until Loop

The Do Until loop is basically the same as the Do Whileloop except that the statements inside a Do Until loopare run only as long as the condition is False. When thecondition becomes True, the loop terminates.


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Syntax ofDo While LoopSyntax ofDo While Loop

a) DoWhile condition

Block of one or more VB statementsLoop

b) DoBlock of one or more VB statements

LoopWhile condition

Note:

By placing theWhile condition in the Do statement, you tellthe program that you want to evaluate the condition beforeyou run any statements inside the loop. If the condition is

True, the repetitive statements between the Do statementand the Loop statement are run. Then the program returnsto the Do statement to evaluate the condition again. To runthe Do While loop at least once, you must use the secondform of the Do While loop. This form of the loop places thecondition in the Loop statement.


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ExampleExample of Using Doof Using Do--While LoopWhile Loop

Private Sub Command1_Click ()

Dim count as Integer

count=0DoWhile count < 10

count = count + 1

Print count

Loop

End Sub


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ExampleExample of Using Doof Using Do--While LoopWhile Loop

Private Sub Command1_Click ()

Dim count as Integer

count=0Do

count = count + 1

Print count

LoopWhile count < 10

End Sub


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Do Until LoopDo Until Loop

a) Do Until conditionBlock of VB statements

Loop

b) DoBlock of VB statements

Loop Until condition

Note:

Do Until loop has two forms: one with the condition in

the Do statement and one with the condition in theLoop statement. If you place the condition in the Dostatement, it is evaluated before the statements in theloop are executed. If you place the condition in theLoop statement, the loop is run at least once before

the condition is evaluated.


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ExampleExample of Using Doof Using Do--Until LoopUntil Loop

Private Sub command1_click()

Dim i As Integer

i = 1

Do Until i > 10

Print i

i = i + 1Loop

End Sub


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ExampleExample of Using Doof Using Do--Until LoopUntil Loop

Private Sub command1_click()

Dim i As Integer

i = 1

Do

Print i

i = i + 1

Loop Until i > 10

End Sub


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While.Wend loopWhile.Wend loop

General Format of ForNext Loop is:-

While Logical expression

One or more VB statements

Wend


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Example of Using While.Wend LoopExample of Using While.Wend Loop

Sum=0

Count=1

While Count


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For....Next LoopFor....Next Loop

General Format of ForNext Loop is:-

Forcounter=startNumber to endNumber (Step increment)

One or more VB statements

Next


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Example of usingExample of using For....Next LoopFor....Next Loop


Dim i As Integer

Fori = 1 To 10

Print i

Next i

End Sub


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Examples of usingExamples of using For....Next LoopFor....Next Loop

(a) For counter=1 to 10

Print counterNext

(b) Forcounter=1 to 1000 step 10

Next

(c) Forcounter=1000 to 5 step -5Print counter

Next


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Nested LoopNested Loop

Fori=1 to 10

Forj=1 to 10Print i, j

Next j

Next i


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USER DEFINEDDATATYPESUSER DEFINEDDATATYPES

It is declared in the General Declarations of a codeIt is declared in the General Declarations of a code

module by using the Type and End Type keywords.module by using the Type and End Type keywords.

E.g. [Private/Public] Type studentE.g. [Private/Public] Type student

RollNo AsRollNo As IntegerInteger

Address AsAddress As StringString

DateofJoin AsDateofJoin As DateDate

TotalFee AsTotalFee As DoubleDouble

Rupees AsRupees As CurrencyCurrency

End TypeEnd Type

This defines a userThis defines a user--defined data type Student that isdefined data type Student that is

used for storing the student details.used for storing the student details.


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Declaring Variables forDeclaring Variables for

UserUser--Defined Data TypeDefined Data Type

WeWe use Dim statement for this.use Dim statement for this.

E.g.E.g. DimDim stud1 Asstud1 As StudentStudent

DeclaresDeclares aa variablevariable studstud11 ofof studentstudent datadata typetype.. ThisThis

variablevariable cancan storestore allall thethe detailsdetails ofof aa studentstudent suchsuch asas thethe

name,name, addressaddress etcetc..


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Retrieving values fromRetrieving values from

UserUser--Defined Data TypeDefined Data Type

AssigningAssigning andand RetrievingRetrieving valuesvalues fromfrom useruser--defineddefined typestypes isis

donedone usingusing thethe ..(DOT)(DOT) operator operator.. ThisThis isis similar similar toto

accessingaccessing propertiesproperties ofof controlscontrols..

EE..gg.. PrivatePrivate SubSub Form_Load()Form_Load()

DimDim studstud11 AsAs StudentStudent

studstud11.. TotalFeeTotalFee ==15001500..5050

studstud11..Address=PvcAddress=PvcMsgBoxMsgBox studstud11..TotalFeeTotalFee && studstud11..AddressAddress

EndEnd SubSub


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GoTo StatementGoTo Statement

ThisThis statementstatement allowsallows thethe controlcontrol toto jumpjump

forwardsforwards oror backwardsbackwards inin thethe samesame procedureprocedure..

ThisThis cancan bebe aa numbernumber oror aa wordword followedfollowed byby aa

coloncolon ((::))..

TheThe GoToGoTo statementstatement isis followedfollowed byby aa labellabel

namename withoutwithout thethe coloncolon..


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Example of Goto StatementExample of Goto Statement

Example :Example : Private Sub Form_Load()Private Sub Form_Load()

Dim x As IntegerDim x As Integer

frmMain.showfrmMain.show

x=0x=0

startloop:startloop:x=x+1x=x+1

print xprint x

if x=10 thenif x=10 then GoToGoTo endloopendloop

GoToGoTo startloopstartloopendloop:endloop:

MsgBox DoneMsgBox Done

EndEnd

End SubEnd Sub

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