introduction to computing dr. nadeem a khan. lecture 7
Post on 20-Dec-2015
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AnnouncementAnnouncement
► New TAs New TAs
Harris MukarramHarris Mukarram
Mubashir Amjad Hunain Mubashir Amjad Hunain
► Visit the Website for their office Visit the Website for their office hourshours
Visual Basic EventsVisual Basic Events
► EventEvent : Action taken by the user e.g.: Action taken by the user e.g.
Clicking a ControlClicking a Control
Double Clicking a ControlDouble Clicking a Control
Getting FocusGetting Focus
Losing Focus Losing Focus
etc. etc.etc. etc.
Visual Basic Events Visual Basic Events (Contd.)(Contd.)► Naming of EventsNaming of Events
Clicking a Command Button 1Clicking a Command Button 1►Command1_ClickCommand1_Click
Double Clicking a Picture Box 2Double Clicking a Picture Box 2►Picture2_DblClickPicture2_DblClick
Text box 1 gets FocusText box 1 gets Focus►Text1_GotFocusText1_GotFocus
Text box 1 loses Focus Text box 1 loses Focus ►Text1_LostFocusText1_LostFocus
Visual Basic Events Visual Basic Events (Contd.)(Contd.)
►Names of eventsNames of events
=> => objectName_eventobjectName_event
►Events are pre-definedEvents are pre-defined
Event ProcedureEvent Procedure
►Event ProcedureEvent Procedure: : block of code to be block of code to be executed when an event occursexecuted when an event occurs
►General formGeneral formSub Sub objectName_event()objectName_event()
statementsstatements
End SubEnd Sub
Event Procedure Event Procedure (Contd.)(Contd.)
►E.g:E.g:Sub Command1_Click()Sub Command1_Click()
statementsstatements
End SubEnd Sub
Sub Text1_GotFocus()Sub Text1_GotFocus()
statementsstatements
End SubEnd Sub
VB StatementsVB Statements
►Statements to change the Statements to change the propertiesproperties of an object of an object
the general form:the general form:LetLet objectName.property = setting objectName.property = setting
Statements Statements (Contd.)(Contd.)
LetLet objectName.property = setting objectName.property = setting
E.g:E.g:
Let Text1.FontSize = 12Let Text1.FontSize = 12
Let Text1.FontBold = TRUELet Text1.FontBold = TRUE
Let Text1.Text = “ ”Let Text1.Text = “ ”
Event Procedure Event Procedure (Contd.)(Contd.)
► Event procedureEvent procedure – general form – general formSub Sub objectName_eventobjectName_event()()
statementsstatementsEnd SubEnd Sub
► ExampleExampleSub Command1_Click()Sub Command1_Click()
Let Text1.text = “”Let Text1.text = “”Let Text2.text=“Hello”Let Text2.text=“Hello”
End SubEnd Sub
Viewing CodeViewing Code
Margin Indicato
r Bar
Procedure View
Full Module View
Object Box
Procedures List Box
Split Bar
MethodsMethods
►Another category of Another category of statements based on methods statements based on methods
Methods Methods (Contd.)(Contd.)
►E.g:E.g:
Picture1.ClsPicture1.Cls
Clears Picture1 Picture BoxClears Picture1 Picture Box
Picture1.Print 3 Picture1.Print 3
Prints ‘3’Prints ‘3’ in the Picture1 Picture Boxin the Picture1 Picture Box
Methods Methods (Contd.)(Contd.)
►General form of these statementsGeneral form of these statements
=> => objectName.Method objectName.Method parametersparameters
(if any)(if any)
TheThe Print Method Print Method
► Picture1.Print Picture1.Print mm ??
► Picture1.Print Picture1.Print mm;; ??
► Picture1.Print Picture1.Print mm; ; nn; ; r r ??
m, n, rm, n, r are numbers e.g. 3, 5.2 are numbers e.g. 3, 5.2
NumbersNumbers
►Numeric Constants Numeric Constants 2, 5.6, 9, 10.0052, 5.6, 9, 10.005
►Arithmetic OperationsArithmetic Operations Addition (2+3)Addition (2+3) Subtraction (2-3)Subtraction (2-3) Multiplication (2*3)Multiplication (2*3) Division (2/3)Division (2/3) Exponentiation (2^3)Exponentiation (2^3)
Numbers Numbers (Contd.)(Contd.)
►Numeric Expressions Numeric Expressions e.g.e.g.
(2+3)/5(2+3)/5
(5+2) * (2- 10/2)(5+2) * (2- 10/2)
2.5*2-3^2+14/72.5*2-3^2+14/7
Numbers Numbers (Contd.)(Contd.)
► How will this be calculated?How will this be calculated?
2+10/52+10/5
5+2* 2- 1/105+2* 2- 1/10
4*6-3^2+5/104*6-3^2+5/10
3^2*53^2*5
Numbers Numbers (Contd.)(Contd.)
►Operator PrecedenceOperator Precedence
1. ^1. ^
2.- operator (indicating a negative 2.- operator (indicating a negative value)value)
3. * and / operator3. * and / operator
4. + and - operator4. + and - operator
Numbers Numbers (Contd.)(Contd.)
►Use parenthesis ( ) to keep intentions Use parenthesis ( ) to keep intentions clearclear
(2+2)*2(2+2)*2 ??
2+2*22+2*2 ??
(5+ (5*2))/(2+1) ?(5+ (5*2))/(2+1) ?
What will be printed?What will be printed?
► Picture1.Print 2*3+2Picture1.Print 2*3+2
► Picture1.Print “hello”Picture1.Print “hello”
► Picture1.Print “2*3+2”Picture1.Print “2*3+2”