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 Application – another name for a program.  Interface – is what appears on the screen when the application is running.  Program Code – is instructions.

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Presentation on theme: " Application – another name for a program.  Interface – is what appears on the screen when the application is running.  Program Code – is instructions."— Presentation transcript:

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2  Application – another name for a program.  Interface – is what appears on the screen when the application is running.  Program Code – is instructions that tells an application’s objects how to behave.  Object Oriented Programming - Uses classes, which are program code and data, to create objects.  Objects- can have visual representation such as a dialog box, button, Label etc.  Event-driven program – when a program runs due to an object being selected by the user.

3  IDE – Integrated Development Environment. ◦ Used to create a Visual Basic application  The Visual Basic IDE consists of: ◦ Menu Bar ◦ Tool Bar ◦ Tool Box ◦ Project Window ◦ Project Explorer Window ◦ Properties Window ◦ Form Layout Window

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5  Menu Bar  Tool Bar  Project Window  Project Explorer Window  Properties Window  Form Layout Window

6  Form – is a container object for other objects

7  Objects are added during design time  The time during which the applications interface is being created.  Label object is used to display information.  Command Button object is something a user can click on.  Objects are added by clicking and moving your mouse over to the screen and dragging it across the form.

8  Properties – defines its appearance, behavior, position, and other attributes.  Each type of objects have many different types of properties.

9  Name – identifies an object all names should start with the prefix “lbl”.  Caption – changes the text displayed in the label  Font – used to change font style, and size.  Alignment – Changes the alignment of text in a label’s caption (left & right justify and center)

10  Name – identifies the object. Prefix “cmd”. Cannot be change at runtime.  Caption – Changes the text displayed in the command button. Example: cmdCancelorDone.Caption = “Done”. Form Properties  Name – identifies an object. Prefix “frm”. Cannot change during runtime.  Caption – changes the text displayed in the title bar. Example: frmUserApp.Caption = “My Application”

11  When naming an object, it should start with the appropriate prefix and then be descriptive of the object’s purpose.

12  Selecting an object is done by simply clicking on it.  Resizing by using the drag handle  Marquee Selection – Selecting the pointer control and create a dash box around several objects at one time.

13  File menu and select the “Save Project” command or clicking on disk icon shortcut key.  First saved – both form and project must be given descriptive names. ◦ Save the form using the same name as its Name Property and then save the project using a descriptive name of the application.

14  F5 – start command  Run Menu and select run  Run icon on the toolbar Run Time  Refers to the time during which application is being executed.  A VB program can be run at any time of its development.

15  Run Menu – select “End” command.  Click the End icon on the Tool Bar.

16  Also refer to as Program  Contains set of instructions that tells the computer how to perform specific task.  Each line of code is referred to as a statement. Event Procedures  Is a block of code that executes in response to an event.  Event (User Event) – is a way in which the user can interact with an object, such as clicking a button.  Specific actions will be taken when the user clicks on the button.

17  Container for program code.  Code Editor – is the area displaying the form module View Code buttonView Object button

18  Display by double-clicking on the form.  Display by clicking on the View Code Button in the Project Explorer.  Clicking the button beside the view code button returns you back to the form.

19  Removes a form from memory and ends the application.  Unload statement requires a form name to be unloaded.  If the form to be unloaded is the current form, then you could use Me ◦ Example:  Unload Me or Unload Form1

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21  Select object name from Object list and then a corresponding event is selected from the Event name.

22  Indicates that the procedure cannot be accessed outside of the form module.  Sub declares the procedures  End Sub – ends the Sub statement.  Body is between Sub and End Sub statements.

23  The interface and program code of an application are printed by selecting the print command from the file menu  CTRL + P Removing a Project from the IDE  File menu – Select the Remove Project command.

24  Assignment – is used to change the value of an object property at run time.  Assignment Statement changes property values using the equal sign (=).  Each Object property can only be assigned a valid property values.

25  Is displayed when typing an object’s name and a dot operator notation mark.

26  Name – Cannot be change during run time by an assignment statement  Caption – Text in double Quote lblMessage.Caption = “Adios”  Font – has several Subproperties Size – 0 – 2048  Example: lblMessage.Font.Size = 10 Bold & Italic are True or False  Example: lblMessage.Font.Bold = True Name – enclosed in double quote  lblMessage.Font.Name = “Arial”  Alignment – 0 – left, 1 – right, 2 – center

27  Event procedures can also be written for form events.  The Form_Load event procedure is executed when the form is loaded into memory.(Application is started or run)  Examples Private Sub Form_Load() lblSample.Caption = “This text is centered.” lblSample.Alignment = 2 End Sub

28  Changing object property values in the Form_Load event procedure is alternative to setting property values in the Properties window.  Initializing the form – Setting object properties through the Form_Load event.

29  Comments – are used to explain and clarify program code for a human reader.  No effect on how the application runs.  Single quotation mark (‘) begins a comment  Mark code that is ambiguous or misleading.  Example: lblSample.Alignment = 0 ‘left justify  All programs should state the following: ◦ ‘ Author: Your Name ◦ ‘ Date: Current Date ◦ ‘ Chapter and Exercises

30  File menu – Open Project  CTRL + O  Open Project Button on the Tool Bar

31  Makes programs more interesting  Makes it easier to interact with.

32  Located in the Tool Box  Used to create Images

33  Name – Use the img prefix when naming and image.  Picture – is used to display a dialog box for selecting the graphic to display in the image area.  Stretch – True or False – True if it has been resized. False otherwise.  Visible – True or False – To display at run time Visible = True. To hide Visible = False.

34  Displays as a box, when added to a form.

35  Go to Property box and select Picture. Click on box on ellipsis.  Stretch should be set to true so image will fit in the image box. Click event  Is when the user clicks on an image object to perform an action.

36  Built-in arithmetic operators ◦ “^” - exponential ◦ “*” - multiplication ◦ “/” – division ◦ “\” – Integer division ◦ “Mod” - Modulus ◦ “+” - addition ◦ “-” - subtraction

37  Arithmetic operators are used to form expressions.  Expression can be anywhere a numeric value is allowed ◦ Example: lblAnswer.Caption = 3.14 * 10^2 ◦ Expressions are NOT enclosed in quotes.

38  Exponentiation  Multiplication and Division Left to Right  Addition and Subtraction Left to Right  You can change order of precedence by using parentheses.

39  Always use parentheses when any ambiguity or maybe questions about the expression.

40  Visual Basic also has a compiler that translate the program code into separate executable file.  Executable file can be run on any Computer that uses Windows 95 or later.  Visual Basic acts as an interpreter that reads each line of program code as it is entered.  Visual Basic will highlight any errors immediately.  Interpreter executes the code line-by-line and displays the output in the IDE.

41  ALT + Q  File menu – Exit

42  Create the program interface first  Name all objects before writing and code.  Use Object list in Code Editor window to select the object event procedure.


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