1. CHAPTER SIX

2. Objectives Add a MenuStrip object Use the InputBox function
Display data using the ListBox object
Understand the use of counters and accumulators
Understand the use of compound operators
Chapter 6: Loop Structures

3. Objectives Repeat a process using a For…Next loop
Repeat a process using a Do loop
Avoid infinite loops
Prime a loop
Validate data
Chapter 6: Loop Structures

4. Objectives Create a nested loop Select the best type of loop
Debug using DataTips at breakpoints
Publish a finished application using ClickOnce technology
Chapter 6: Loop Structures

5. Introduction
A fundamental process in a computer program is to repeat a series of instructions either while a condition is true (or not true) or until a condition is true (or not true)
The process of repeating a set of instructions while a condition is true or until a condition is true is called looping
Another term for looping is iteration
Chapter 6: Loop Structures

6. User Interface Design
A menu bar is a strip across the top of a window that contains one or more menu names
A menu is a group of commands, or items, presented in a list
Chapter 6: Loop Structures

7. User Interface Design
With a Windows Form object open in the Visual Studio window, scroll in the Toolbox to display the Menus & Toolbars category. If the category is not open, tap or click the expand icon (the right-pointing triangle) next to the Menus & Toolbars category name. Drag the MenuStrip .NET component to the Windows Form object
Release the mouse button
With the MenuStrip object selected, scroll in the Properties window until the (Name) property is visible. Change the MenuStrip object name to mnuFitness
Tap or click the Type Here box on the menu bar. Type &File to identify the File menu, and then press the ENTER key
Chapter 6: Loop Structures

8. User Interface Design
Tap or click File in the MenuStrip object to select it, scroll in the Properties window to the (Name) property, and then change the name to mnuFile
To add a menu item to the File menu, tap or click the Type Here box below the File menu name. Type &Clear and then press ENTER to create a new menu item named Clear with C as the hot key
On the File menu, tap or click Clear to select it, scroll in the Properties window until the (Name) property is visible, and then change the name to mnuClear
Chapter 6: Loop Structures

9. User Interface Design
Chapter 6: Loop Structures

10. Event Handlers for Menu Items
In Design view, double-tap or double-click the Exit menu item to open the code window
Using IntelliSense, enter the Close procedure call to close the window and terminate the application
Chapter 6: Loop Structures

11. Inserting Standard Items for a Menu
Visual Basic 2012 contains an Action Tag that allows you to create a full standard menu bar commonly provided in Windows programs
Action tags provide a way for you to specify a set of actions, called smart actions, for an object as you design a form
With a new Windows Form object open, drag the MenuStrip .NET component onto the Windows Form object. Tap or click the Action Tag on the MenuStrip object
Tap or click Insert Standard Items on the MenuStrip Tasks menu
Tap or click File on the menu bar to view the individual menu items, their associated icons, and their shortcut keys
Chapter 6: Loop Structures

12. Inserting Standard Items for a Menu
Chapter 6: Loop Structures

13. InputBox Function
The InputBox function displays a dialog box that consists of a message asking for input, an input area, a title, an OK button, and a Cancel button
When the user enters the text and taps or clicks the OK button, the InputBox function returns this text as a string
If the user taps or clicks the Cancel button, the function returns a null string ("")
Chapter 6: Loop Structures

14. InputBox Function
Chapter 6: Loop Structures

15. Creating the InputBox Object for Fitness Challenge Application
Chapter 6: Loop Structures

16. Displaying Data Using the ListBox Object
Drag the ListBox object from the Toolbox to where you want to place the ListBox object on the Windows Form object. When the pointer is in the correct location, release the left mouse button
With the ListBox object selected, scroll in the Properties window to the (Name) property. Name the ListBox object lstWeightLoss
Chapter 6: Loop Structures

17. Displaying Data Using the ListBox Object
Chapter 6: Loop Structures

18. Adding ListBox Items During Design
Assume the lstStores ListBox object already has been placed and named on the Windows Form object. Select the ListBox object on the Windows Form object and then tap or click the Items property in the Properties window
Tap or click the ellipsis button in the right column of the Items property
Tap or click in the String Collection Editor window. Type the following items to represent popular retail stores, pressing ENTER at the end of each line:
Abercrombie & Fitch
Aeropostale
American Eagle
Express
Hollister
Tap or click the OK button
Chapter 6: Loop Structures

19. Adding ListBox Items During Design
Chapter 6: Loop Structures

20. SelectedItem Property
Chapter 6: Loop Structures

21. Accumulators, Counters, and Compound Operators
A variable that contains an accumulated value such as the total of all the weight loss values is called an accumulator
A variable that always is incremented by a constant value is called a counter
Chapter 6: Loop Structures

22. Accumulators, Counters, and Compound Operators
A compound operator allows you to add, subtract, multiply, divide, use modulus or exponents, or concatenate strings, storing the result in the same variable
Chapter 6: Loop Structures

23. Accumulators, Counters, and Compound Operators
Chapter 6: Loop Structures

24. Accumulators, Counters, and Compound Operators
Chapter 6: Loop Structures

25. Using Loops to Perform Repetitive Tasks
In the Fitness Challenge application, the user enters weight loss values in an InputBox for up to eight team members
The repetitive process of entering eight weight loss values can be coded within a loop to simplify the task with fewer lines of code
Each repetition of the loop is called an iteration
Chapter 6: Loop Structures

26. Repeating a Process Using the For…Next Loop
You can use a For...Next loop when a section of code should be executed an exact number of times
Chapter 6: Loop Structures

27. Repeating a Process Using the For…Next Loop
Chapter 6: Loop Structures

28. Step Value in a For…Next Loop
A Step value is the value in a For...Next loop that is added to or subtracted from the beginning value on each iteration of the loop
Default step value is 1
Can be positive or negative, contain decimals, or include variables and mathematical expressions
Chapter 6: Loop Structures

29. Entering the For…Next Loop Code
Chapter 6: Loop Structures

30. Repeating a Process Using a Do Loop
In a Do loop, the body of the loop is executed while or until a condition is true or false
The Do While loop executes as long as the condition is true
The Do Until loop executes until the condition becomes true
A top-controlled loop is tested before the loop is entered
Body might not be executed
Bottom-controlled loops test the condition at the bottom of the loop
Body executes at least once
Chapter 6: Loop Structures

31. Top-Controlled Do While Loops
A top-controlled Do While loop begins with the keywords Do While. Next, the condition is specified
The body of the loop contains the instructions that are executed as long as the condition is true
A loop that does not end is called an infinite loop
Chapter 6: Loop Structures

32. Top-Controlled Do While Loops
Chapter 6: Loop Structures

33. Entering a Do Loop Using IntelliSense
In the code window, enter the intScore variable declaration and then press the ENTER key. Type Do While and a space to display the IntelliSense list. Type ints to highlight intScore in the list
Type < 5 and then press the ENTER key.
Type ints to highlight the intScore variable. Complete the statement by typing += 1 and then pressing the ENTER key. Press the DELETE key to delete the blank line
Chapter 6: Loop Structures

34. Entering a Do Loop Using IntelliSense
Chapter 6: Loop Structures

35. Bottom-Controlled Do While Loop
A bottom-controlled loop works the same way as the top-controlled Do While loop
The body of the loop is executed before the condition is checked the first time, guaranteeing at least one iteration of a loop will be completed
Chapter 6: Loop Structures

36. Bottom-Controlled Do While Loop
Chapter 6: Loop Structures

37. Do Until Loops
Chapter 6: Loop Structures

38. User Input Loops
Do loops often are written to end the loop when the user enters a certain value or performs a certain action such as tapping or clicking the Cancel button in an input box
Chapter 6: Loop Structures

39. Avoiding Infinite Loops
An infinite loop is a loop that never ends
Chapter 6: Loop Structures

40. Priming the Loop
Starting a loop with a preset value in the variable(s) tested in the condition is called priming the loop
Chapter 6: Loop Structures

41. Validating Data
Chapter 6: Loop Structures

42. Creating a Nested Loop
Any loop can be placed within another loop under the following conditions:
Interior loops must be completely contained inside the outer loop
Must have a different control variable
Chapter 6: Loop Structures

43. Selecting the Best Loop
Use a Do loop if the number of repetitions is unknown and is based on a condition changing; a For...Next loop is best if the exact number of repetitions is fixed
If a loop condition must be tested before the body of the loop is executed, use a top-controlled Do While or Do Until loop. If the instructions within a loop must be executed one time regardless of the status of a condition, use a bottom-controlled Do While or Do Until loop
Use the keyword While if you want to continue execution of the loop while the condition is true. Use the keyword Until if you want to continue execution until the condition is true
Chapter 6: Loop Structures

44. Using a DataTip with Breakpoints
Resolving defects in code is called debugging
A good way to collect information is to pause the execution of the code where a possible error could occur
Breakpoints are stop points placed in the code to tell the Visual Studio 2012 debugger where and when to pause the execution of the application
While in break mode, you can examine the values in all variables that are within the scope of execution through the use of DataTips
Chapter 6: Loop Structures

45. Using a DataTip with Breakpoints
With the application open in the code window, press and hold or right-click line 46, which contains the code where you want to set a breakpoint, and then point to Breakpoint on the shortcut menu
Tap or click Insert Breakpoint on the submenu
To run and test the program with the breakpoint, tap or click the Start Debugging button on the Standard toolbar
Tap or click the Enter Weight Loss button. Type 3.4 as the weight loss amount of the first team member
Tap or click the OK button in the input box
Chapter 6: Loop Structures

46. Using a DataTip with Breakpoints
Point to the variable decWeightLoss on line 46
You can view the value in any other variable within execution scope by pointing to that variable. To illustrate, point to the variable decTotalWeightLoss on line 46
Continue the program by tapping or clicking the Continue button on the Standard toolbar. Notice that the Continue button is the same as the Start Debugging button
Point to the decTotalWeightLoss variable
Chapter 6: Loop Structures

47. Using a DataTip with Breakpoints
Chapter 6: Loop Structures

48. Using a DataTip with Breakpoints
To remove a breakpoint, press and hold or right-click the statement containing the breakpoint, and then point to Breakpoint on the shortcut menu
Tap or click Delete Breakpoint on the Breakpoint submenu
Chapter 6: Loop Structures

49. Publishing an Application with ClickOnce Deployment
After an application is completely debugged and working properly, you can deploy the project
Deploying a project means placing an executable version of the program on your hard disk, on a Web server, or on a network server
When programming using Visual Basic 2012, you can create a deployed program by using ClickOnce Deployment
The deployed version of the program you create can be installed and executed on any computer that has the .NET framework installed
Chapter 6: Loop Structures

50. Publishing an Application with ClickOnce Deployment
With the application open, tap or click BUILD on the menu bar
Tap or click Publish Fitness Challenge on the BUILD menu
Change the default location from publish\ to a file location. To publish to a USB drive, type the drive letter. In this example, enter E: for a USB drive
Tap or click the Next button. If necessary, tap or click the From a CD-ROM or DVD-ROM radio button
Tap or click the Next button. If necessary, tap or click the “The application will not check for updates” radio button
Chapter 6: Loop Structures

51. Publishing an Application with ClickOnce Deployment
Tap or click the Next button
Tap or click the Finish button
To view the finished result, minimize the Visual Studio window and then open the Search charm. Type Computer in the Search box. Double-tap or double-click the USB drive icon to view the published installation folder
To install the application, double-tap or double-click the setup file
After installation, the program runs. To run the installed application again, open the Search charm, type Fitness, and then click the Fitness Challenge icon
Chapter 6: Loop Structures

52. Publishing an Application with ClickOnce Deployment
Chapter 6: Loop Structures

53. Program Design
Chapter 6: Loop Structures

54. Program Design
Chapter 6: Loop Structures

55. Event Planning Document
Chapter 6: Loop Structures

56. Summary Add a MenuStrip object Use the InputBox function
Display data using the ListBox object
Understand the use of counters and accumulators
Understand the use of compound operators
Chapter 6: Loop Structures

57. Summary Repeat a process using a For…Next loop
Repeat a process using a Do loop
Avoid infinite loops
Prime a loop
Validate data
Chapter 6: Loop Structures

58. Summary Create a nested loop Select the best type of loop
Debug using DataTips at breakpoints
Publish a finished application using ClickOnce technology
Chapter 6: Loop Structures

59. CHAPTER SIX COMPLETE