Working with Comparison Operators

Jesselle Capa

Charles Justine Bool

Comparison Operators

Operators that compare data values to produce true or false results.

ASCII Contains a list of characters with

corresponding unique numeric representation

Comparison OperatorsOperator Usage Description

> lblSales.Caption > Goal

The greater than operator return True Only if the value on the right.

< Pay < 2000.0 The less than operator return True if the value on the left of < is less than the value on the right.

= Age = Limit The equal to operator return True if the value on the both sides of = are equal.

>= FirstName >= “Mike”

The greater than or equal to operator return True if the value on the left of >= is greater than or equal to the value on the right.

<= Num <= lblAmt.Caption

The less than or equal to operator return True if the value on the left of <= is less than or equal to the value on the right.

<> txtAns.text<> “Yes”

The not equal to operator return True if the value on the left of <> is unequal to the value on the right.

Relationship ResultsRelation Result

2 > 1 True

3 < 3 False

5 > 10 True

“Apple” <= “Orange” True

“Macdonald “ < “Mc Donald” True

0 >=0 True

0 <=0 True

1 <>2 True

2 >=3 False

Working with If Statement

The If statement provides logic for the application, w/c analyzes data and makes decisions based on the analysis.

The If statement uses comparison operators to test data values and performs one of two possible actions based on the results of the comparison’s test.

Without the If statement, the application code will sequentially execute . Meaning , one statement is executed after another.

The If statement is usually written in the following format:

If comparisonTest Then

One or more statements

End If

If Statement and ComparisonKeep in mind that the body of the If statement

executes based on the results of the comparison test. The statement executes if the results is true. Otherwise , the rest of the application executes as usual and the If statement will be skipped.

Data that are entered into a text box control is treated as a Variant data type . When arithmetic is performed with a Variant with data type that holds a numeric value . Visual Basic will convert such data to a number for the calculation purposes.

The If statement's Else Branching

The If statement with Else is usually written in the following format:

If comparisontest Then

one or more statements

Else

one or more statements

End If

Compound Comparison with the Logical Operators

Operator Usage Description

And If (A > B) And (C < D)

Returns True if both sides of the And are true.

Or If (A > B) Or (C < D) Returns True if either side of the Or is true.

Not If Not (strAns = “Yes”)

Returns the opposite true or false result.

Example :

Private Sub cmdGetStudentGrade_Click()

‘Code for Generating Student's Grade‘Declare VariablesDim percent As Integer, studentmark As String

‘Clear text Box txtGrade.Text = "" ‘Get Students Mark from inputbox percent = InputBox("Enter Students Percent")

'Begin if statement If percent >= 50 And percent < 60 Then studentmark = "C" Else percent >= 60 And percent < 70 Then studentmark = "B" Else percent >= 70 Then studentmark = "A" Else studentmark = "FAIL" End If 'Display Output txtGrade.Text = studentmarkEnd Sub

Nesting If-Else Statements

If (intAge = 5) ThenlblTitle.Caption = “Kindergarten”

ElseIf (intAge = 6) Then

lblTitle.Caption = “1st Grade”Else

If (intAge = 7) ThenlblTitle.Caption = “2nd

Grade”

If (intAge = 8) ThenlblTitle.Caption = “3rd Grade”

Else If (intAge = 9) Then

lblTitle.Caption = “4th Grade” Else

If (intAge = 10) Then lblTitle.Caption = “5th Grade” Else

If (intAge = 11) Then lblTitle.Caption = “6th Grade”

Else

lblTitle.Caption = "Advanced" End If End If

End If End If End If End IfEnd If

Using Select Case StatementThe Select Case Statement handles multiple –

choice conditions better than If-Else . When several choices are possible , programmers usually use Select Case as a substitute for long , nested If-Else , but you may find out that it is easier to code and to maintain . However , you must avoid using the Select Case if you will have a simple If or If-Else for the code , unless you need to compare against more than two values . Otherwise , stick with the simple If and If-Else statements

Select Case intAge Case 5 : lblTitle.Caption = "Kindergarten" Case 6 : lblTitle.Caption = "1st Grade" Case 7 : lblTitle.Caption = "2nd Grade" Case 8 : lblTitle.Caption = "3rd Grade" Case 9 : lblTitle.Caption = "4th Grade" Case 10 : lblTitle.Caption = "5th Grade Case 11 : lblTitle.Caption = "6th Grade Case Else : lblTitle.Caption = "Advanced"End Select

3 Select Case Optional Formats:

Select Case ExpressionsCase Is Relation :

One or more Statements Case Is Relation :

One or more Statements[Case Is Relation :

One or more Statements][Case Is Relation :

One or more Statements]End Else

Select Case Expressions

Case ValueOne or more Visual Basic StatementsCase ValueOne or more Visual Basic Statements[Case ValueOne or more Visual Basic Statements][Case ValueOne or more Visual Basic Statements]

End Else

Select Case Expressions

Case expr1 To expr2 :One or more Visual Basic Statements

Case expr1 To expr2 :One or more Visual Basic Statements

[Case expr1 To expr2 :One or more Visual Basic Statements]

[Case Else :One or more Visual Basic Statements]

End Else

THE

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