STUDENT SOLUTIONS MANUAL

Transcription

1 Student Solutions Manual (Page 1 of 211) STUDENT SOLUTIONS MANUAL to accompany An Introduction to Programming Using Visual Basic 2010, 8th Edition by David I. Schneider

2 Student Solutions Manual (Page 2 of 211) Copyright 2011 by Pearson Higher Education. All rights reserved.

3 Student Solutions Manual (Page 3 of 211) CONTENTS Chapter Comments Chapter 2 Visual Basic Controls and Events Exercises 2.2 Visual Basic Controls 11 Exercises 2.3 Visual Basic Events 15 Chapter 3 Variables, Input, and Output Exercises 3.1 Numbers 18 Exercises 3.2 Strings 21 Exercises 3.3 Input and Output 26 Chapter 4 Decisions Exercises 4.1 Relational and Logical Operators 30 Exercises 4.2 If Blocks 31 Exercises 4.3 Select Case Blocks 38 Exercises 4.4 Input via User Selection 42 Chapter 5 General Procedures Exercises 5.1 Function Procedures 47 Exercises 5.2 Sub Procedures, Part I 50 Exercises 5.3 Sub Procedures, Part II 55 Chapter 6 Repetition Exercises 6.1 Do Loops 57 Exercises 6.2 For Next Loops 62 Exercises 6.3 List Boxes and Loops 68 Chapter 7 Arrays Exercises 7.1 Creating and Accessing Arrays 77 Exercises 7.2 Using LINQ with Arrays 85 Exercises 7.3 Arrays of Structures 89 Exercises 7.4 Two-Dimensional Arrays 99 Chapter 8 Text Files Exercises 8.1 Managing Text Files 106 Exercises 8.2 StreamReaders, StreamWriters, Structured Exception Handling 111 Exercises 8.3 XML 115 Chapter 9 Additional Controls and Objects Exercises 9.1 List Boxes and Combo Boxes 120 Exercises 9.2 Eight Additional Controls and Objects 125 Exercises 9.3 Multiple-Form Programs 132 Exercises 9.4 Graphics 142

4 Student Solutions Manual (Page 4 of 211) Chapter 10 Databases Exercises 10.1 An Introduction to Databases 151 Exercises 10.2 Editing and Designing Databases 164 Chapter 11 Object-Oriented Programming Exercises 11.1 Classes and Objects 165 Exercises 11.2 Working with Objects 172 Exercises 11.3 Inheritance 186 Chapter 12 Web Applications Exercises 12.1 Programming for the Web, Part Exercises 12.2 Programming for the Web, Part Exercises 12.3 Using Databases in Web Programs 204

5 Student Solutions Manual (Page 5 of 211) Chapter 1 Chapter Comments 1. Your instructor might skip this chapter. If so, I recommend that you take a quick look at two items from the chapter. Look at the last question and answer on page 3 to see how the appearance of a program varies with the version of Windows being used. Also, look at the discussion of "Displaying File Extensions" on pages 5 and 6. I recommend that you configure Windows to show all file extensions. Chapter 2 1. On page 44 you are asked to run a program that was downloaded from the Pearson website for the book. All of the programs appearing in Examples and Case Studies can be downloaded from that website. There is never any need for you to manually type in the code for a program in this textbook. The website also contains all the text files, databases, and pictures needed for the exercises. All of these files are contained in the folders Ch02, Ch03, Ch04, and so on. Each chapter file contains a subfolder named Text_Files_for_Exercises which contains the text files needed for that chapter s exercises. The folder Ch09 has a subfolder named Pictures that contains picture files. The folders Ch10 and "Ch12" have a subfolder named Databases containing all the databases needed for the exercises. Each program is contained in a folder with a name in the form chapter section example number. For instance, the program in Chapter 3, Section 1, Example 2 is contained in the folder Many of the programs make use of a text file in the subfolder Debug of the program s bin subfolder. 2. At the top of page 44, we explain our use of ellipses (...) as place holders for the phrase "ByVal sender As System.Object, ByVal e As System.EventArgs". A program will not run when the phrase is replaced with an ellipsis. However, a program will run if the phrase is simply deleted. Therefore, if you use Ctrl+C to copy code from this Student Solutions Manual and paste it into your own program, the code will execute after you delete the ellipses. 3. Every program you write requires use of the Properties window. By default, the Properties window is docked to the right side of the IDE. You might find the Properties window easier to use if you undock it while setting properties. If you double-click on the Properties window s title bar, the window will become undocked and larger. After you have finished using the Properties window, right-click on its title bar and click on Dock. Note: This process also can be used to undock (and redock) the Toolbar and the Solution Explorer window.

6 Student Solutions Manual (Page 6 of 211) Chapter 3 1. Figure 3.1 on page 70 shows the settings for Options Explicit, Strict, and Infer set to On. Most instructors will recommend that the first two Options be set to On. Option Infer, on the other hand, is controversial. (The default setting is On.) If you want to learn more about the effect of Option Infer, take a quick look at the discussion of local type inference on page On page 77, we discuss line continuation. In earlier versions of Visual Basic, the underscore character was needed to continue a statement onto another line. Beginning with VB2010, the underscore character can be omitted when a line that obviously has a continuation (such as, when the line ends with a comma or an arithmetic operator) and therefore will seldom be needed in the programs you write. Underscore characters frequent appear in the answer section of the book and in the Student Solutions Manual following the word "Handles". This was necessary due to the fact that we must limit the length of lines in a printed page. 3. A discussion of sending output to the printer is presented at the end of Section 3.3. This material is optional. If your instructor decides to skip this topic, you might want to take a quick look (just a few minutes) to see what's involved in printing the output of a program. This material is not needed in the textbook. I included it at the request of some instructors. Chapter 4 1. Section 4.1 is unusual in that you will not be asked to write any programs in the exercise set. However, the concepts presented in this section will be fundamental to the rest of the textbook. 2. In Chapter 3 we used list boxes to display data. In Section 4.4, we show how list boxes are used to allow the user to make selections. Another control used to make a selection from a list, a combo box, will be discussed in Chapter The first two sentences after Figure 4.12 on page 149 should read as follows: When you click on an unselected item in a list box, the SelectedIndexChanged event is raised. When you click on a check box or on an unchecked radio button, the CheckedChanged event is raised.

7 Student Solutions Manual (Page 7 of 211) Chapter 5 1. Except for the three case studies, Function procedures appear in many more programs than Sub procedures. The use of Sub procedures is part of good programming practice, but it is not essential. Any computer program can be written without Sub procedures. However, there are a number of programs in this textbook that would be very difficult to write without Function procedures. 2. The above comment is not intended to diminish the importance of Sub procedures. They are a fundamental component of good program design. However, if you find Sub procedures somewhat confusing at first, don't worry. You will still be able to work the exercises. You will eventually become comfortable with Sub procedures after seeing them used in subsequent chapters. Chapter 6 1. There are two types of loops presented in this chapter Do loops and For...Next loops. A third type of loop, called a For Each loop, will be presented in Section Loops have traditionally been used to process lists of data. For instance, loops can be used with a list of numbers to compute the sum of the numbers, the average of the numbers, the largest number in the list and the smallest number in the lists. The algorithms for calculating sums and averages is obvious. In Example 4 of Section 6.3, the maximum value of the numbers in a list box are calculated with the following algorithm: (a) Declare a variable named max. (b) Assign a value to the variable that is guaranteed to be less than or equal to the maximum value in the list. One possibility is to set the value of max equal to the first number in the list. Another possibility requires some knowledge of the number in the list. For instance, if the number are all grades on an exam, the initial value of max can be set to 0. (c) Use a loop to examine the numbers one at a time. Whenever a number is greater than the current value of max, change the value of max to be that number. After the loop has executed, the value of max will be the largest number in the list. Example 4 uses an analogous algorithm to find the smallest number in the list box. These two algorithms appear several times in the textbook in both examples and exercises. 3. Section 6.3 presents techniques for processing lists of data with loops. In Section 7.2, a method for processing lists without using loops will be presented.

8 Student Solutions Manual (Page 8 of 211) Chapter 7 1. A very important idea to take away from Section 7.1 is that there are four ways to fill an array. Let's illustrate the ways by filling an array with the names of the first three presidents. (a) Dim pres() As String = {"Washington", "Jefferson", "Adams} (b) Dim pres() As String = IO.File.ReadAllLines("Pres.txt"), where the text file Pres.txt is located in the program's bin\debug folder of the program and contains three lines (each containing the name of a president). (c) Dim strvar As String = "Washington,Jefferson,Adams" Dim pres() As String = strvar.split(","c) (d) Dim pres(2) As String pres(0) = "Washington" pres(1) = "Jefferson" pres(2) = "Adams" In the first three ways, the array is declared and sized automatically at the same time it is filled. The second and third ways will be the most used in this book. 2. Section 7.3 is perhaps the most challenging section in the book. However, the techniques presented in this section are very powerful and are heavily used later in the book with text files and databases. The techniques also are presented in Section 8.1 in a slightly different form. Some instructors will skip Section 7.3 and rely solely on Section Some important text files used in this chapter are as follows: a. Baseball.txt: contains statistics for all of the players in the major league who had at least 350 at bats in b. Justices.txt: contains all people who served on the U.S. Supreme Court prior to May c. SBWinners.txt: contains all Super Bowl winners up to and including Chapter 8 1. The two sections in this chapter are independent of each other. 2. The preliminaries section at the beginning of Section 8.1 can be omitted if you covered Section 8.3. The techniques presented in the preliminaries will take a fair amount of effort to master. However, the payoff will be substantial. 3. Section 8.1 shows some modern techniques for combining lists of data. In earlier versions of Visual Basic, these tasks could only be carried out with complicated algorithms involving loops.

9 Student Solutions Manual (Page 9 of 211) 4. Some important data files used in this chapter are as follows: a. Baseball.xml: contains statistics for all of the players in the major league who had at least 350 at bats in b. Justices.txt: contains all people who served on the U.S. Supreme Court prior to the summer of Justice Stevens retired in the summer of If you want to update the file after his replacement is named, change the last entry in his record to 2010 and add a record for the person replacing him. c. Senate111.txt: contains the composition of the U.S. Senate as of May 1, d. USPres.txt: contains the names of all U.S. Chapter 9 1. Most of Chapter 9 is not needed in the remainder of the book. However, the chapter shows how to use several tools that are familiar to you from major programs you have used. 2. Programs written by professional programmers often use more than one form. Section 9.3 shows how this is done. However, since this is an introductory book, all programs outside of Section 9.3 use only one form. Chapter The steps for binding a database to a program may look complicated at first. However, after you get used to it you will find it easy and quick to carry out. Also, when you work several exercises using the same database, you can just bind the database once and write a different event procedure for each exercise. 2. Some important databases used in this chapter are as follows: a. Baseball.accdb: contains statistics for all of the players in the major league who had at least 350 at bats in b. Justices.accdb: contains all people who served on the U.S. Supreme Court prior to the summer of c. UN.accdb: contains the composition of the United Nations as of May 1, d. Exchrate.accdb: contains currency exchange rates in December Chapter This chapter is independent of the rest of the book.

10 Student Solutions Manual (Page 10 of 211) Chapter The programs in the chapter are not created with Visual Basic. Most people will use Visual Web Developer that is contained on the DVD packaged with this book. However, if you have a complete version of Visual Studio, you do not have to install Visual Web Developer. The Visual Studio File menu contains the items New Web Site and Open Web Site that you can use to create and access Web programs. 2. Be sure to read the solution to the practice problem in Section It shows you how to save a lot of time when writing the programs for the exercise set.

11 Student Solutions Manual (Page 11 of 211) CHAPTER 2 EXERCISES After a button is clicked it has a blue border. 3. Click on the form to make it the selected object. Click on the Properties window or Press F4 to activate the Properties window. Select the Text property. Type "CHECKING ACCOUNT". 5. Double-click the TextBox icon in the Toolbox. Activate the Properties window. Select the BackColor property. Click on the down-arrow to the right of the Settings box. Click on the Custom tab, and then click on the desired yellow in the palette. Click on the form to see the empty yellow text box. 7. Double-click on the Label icon in the Toolbox. Activate the Properties window, and select the AutoSize property. Set the AutoSize property to False. Select the Text property and type the requested sentence. Select the TextAlign property. Click on the down-arrow button to the right of the Settings box, and click on one of the center rectangles. Resize the label so that the sentence occupies three lines. 9. Double-click on the TextBox icon in the Toolbox. Activate the Properties window. Set the Name property to txtlanguage. Select the Text property and type "Visual Basic 2010". Select the Font property and click on the ellipsis to the right of the Settings box. Scroll up the Font list box, and click on Courier New in the Font box. Click OK. Widen the text box to accommodate its text. 11. Double-click on the Button icon in the Toolbox. Activate the Properties window, and select the BackColor property. Click on the down-arrow button to the right of the Settings box. Click on the Custom tab, and then click on the white square in upper-left corner of the palette. Select the Text property and type "PUSH". Select the Font property, and click on the ellipsis. Click on Italic (with XP or Vista) or Oblique (with Windows 7) in the "Font style" list. Click on 24 in the Size box and click OK. Resize the button.

12 Student Solutions Manual (Page 12 of 211) 13. Double-click on the Button icon in the Toolbox. Activate the Properties window. Select the Text property and type "PUS&H". Click on the form to see the resulting button. 15. Double-click on the Label icon in the Toolbox. Activate the Properties window. Select the Name property and type "lblaka". Select the Text property and type "ALIAS". Select the AutoSize property and set it to False. Select the Font property and click on the ellipsis. Click on Italic (with XP or Vista) or Oblique (with Windows 7) in the "Font style" list. Click OK. Select the TextAlign property, click on the down-arrow box to the right of the Settings box, and click on one of the center rectangles. 17. Double-click on the Label icon in the Toolbox. Activate the Properties window, and select the TextAlign property. Click on the down-arrow box to the right of the Settings box, and click on one of the rectangles on the right. Select the AutoSize property and set it to False. Select the Text property, type "VISUAL BASIC", and press Enter. If the words " VISUAL BASIC " are on one line, resize the label until the words occupy two lines. 19. Double-click on the Label icon in the Toolbox. Activate the Properties window, and select the Font property. Click on the ellipsis to the right of the Settings box. Click on Wingdings in the Font box. Click on the largest size available (72) in the Size box. Click OK. Select the Text property and change the setting to a less than sign (<). Click on the label. (Note: If you didn't know that the less than symbol corresponded to a diskette in the Wingdings font, you could double-click on the diskette character in the Character Map, click the Copy button, select the Text property, and press Ctrl+V. The less than character will appear in the Text settings box.) 21. Double-click on the ListBox icon in the Toolbox. Activate the Properties window, and select the BackColor property. Click on the down-arrow button to the right of the Settings box. Click on the Custom tab and click on the desired yellow square in the palette. Click on the form to see the yellow list box.

13 Student Solutions Manual (Page 13 of 211) 23. In the Solution Explorer window, right click on Form1.vb and select Rename from the context menu. Type frmyellow.vb. Right-click on the form in the Form Designer, and select Properties from the context menu. Click on BackColor property in the Properties window. Click on the down-arrow button in the right part of the Settings box, click on the Custom tab, and click on a yellow square. 25. Begin a new project. Change the text in the form's title bar to "Dynamic Duo". Place two buttons on the form. Position and resize the buttons as shown. Enter Batman as the text of the first button, and enter Robin as the text of the second button. Increase the font size for both buttons to Begin a new project. Change the text in the form's title bar to "Fill the Blank". Place a label, a text box, and another label on the form at appropriate locations. Change the Text setting of the first label to "I m the king of the" and the Text setting of the second label to "A Quote by Leonardo DiCaprio". 29. Begin a new project. Change the text in the form's title bar to "Uncle's Advice". Place five labels and three buttons on the form. Change the Text setting of each label as indicated. Change the settings of the buttons' Text properties to "1", "2", and "3". Resize and position the labels and buttons Each arrow key moves the text box in the indicated direction. 37. Pressing the right and left arrow keys widens and narrows the text boxes, buttons, and list boxes in the group of selected controls. The up and down arrow keys shorten and lengthen the buttons and list boxes in the group. The arrow keys have no effect on the labels, and only the left and right arrow keys affect the text boxes.

14 Student Solutions Manual (Page 14 of 211) 39. Drag a label and a list box onto the form. Click on the label. Hold down the Ctrl key and click on the list box. (You have now selected a group of two controls.) In the Properties window, click on the plus sign (in XP) or the right-pointing triangle (Vista or Windows 7) to the left of the Font property. Click on the Size property, change the setting to 12, and press the Enter key. (Alternative: Replace the last three lines with the following steps.) In the Properties window, select the Font property. Click on the ellipsis button to the right of the Settings box. Click on 12 in the Size list and click OK. 41. The label is positioned just to the left of the text box, and the middles of the two controls are aligned. 43. Center refers to the midpoint horizontally, whereas middle refers to the midpoint vertically. 45. First blue snap line: tops of the two controls are aligned Purple snap line: middles of the two controls are aligned Second blue snap line: bottoms of the two controls are aligned 47. The setting is cycling through the different available colors.

15 Student Solutions Manual (Page 15 of 211) EXERCISES The word "Hello" 3. The word "Hello" on an orange-colored background 5. The text box vanishes. 7. The word "Hello" in green letters 9. The word "Hello" on a gold background. 11. Form1.Text should be Me.Text. 13. Red should be replaced with Color.Red. 15. Font.Size is a read-only property. The statement txtoutput.text = txtbox.font.size is valid since it is reading the value of txtbox.font.size. However, txtbox.font.size = 20 is not valid since it is setting the value of txtbox.font.size. 17. lbltwo.text = "E.T. phone home." 19. txtbox.forecolor = Color.Red txtbox.text = "The stuff that dreams are made of." 21. txtbox.enabled = False 23. lbltwo.visible = False 25. btnoutcome.enabled = True 27. txtboxtwo.focus() 29. The Enter event occurs when a control gets the focus. 31. Private Sub Label1_Click(...) Handles Label1.Click lstoutput.items.add("click") Private Sub Label1_DoubleClick(...) Handles Label1.DoubleClick lstoutput.items.add("double Click") Whenever the DoubleClick event is raised, the Click event is also raised. 33. Private Sub btnleft_click(...) Handles btnleft.click txtbox.text = "Left Justify" txtbox.textalign = HorizontalAlignment.Left Private Sub btncenter_click(...) Handles btncenter.click txtbox.text = "Center" txtbox.textalign = HorizontalAlignment.Center Private Sub btnright_click(...) Handles btnright.click txtbox.text = "Right Justify" txtbox.textalign = HorizontalAlignment.Right

16 Student Solutions Manual (Page 16 of 211) 35. Private Sub btnred_click(...) Handles btnred.click txtbox.backcolor = Color.Red Private Sub btnblue_click(...) Handles btnblue.click txtbox.backcolor = Color.Blue Private Sub btnwhite_click(...) Handles btnwhite.click txtbox.forecolor = Color.White Private Sub btnyellow_click(...) Handles btnyellow.click txtbox.forecolor = Color.Yellow 37. Private Sub txtlife_enter(...) Handles txtlife.enter txtquote.text = "I like life, it's something to do." Private Sub txtfuture_enter(...) Handles txtfuture.enter txtquote.text = "The future isn't what it used to be." Private Sub txttruth_enter(...) Handles txttruth.enter txtquote.text = "Tell the truth and run." 39. Private Sub btnone_click(...) Handles btnone.click btnone.visible = False btntwo.visible = True btnthree.visible = True btnfour.visible = True Private Sub btntwo_click(...) Handles btntwo.click btnone.visible = True btntwo.visible = False btnthree.visible = True btnfour.visible = True Private Sub btnthree_click(...) Handles btnthree.click btnone.visible = True btntwo.visible = True btnthree.visible = False btnfour.visible = True Private Sub btnfour_click(...) Handles btnfour.click btnone.visible = True btntwo.visible = True btnthree.visible = True btnfour.visible = False

17 Student Solutions Manual (Page 17 of 211) 41. Private Sub btnvanish_click(...) Handles btnvanish.click lblface.visible = False Private Sub btnreappear_click(...) Handles btnreappear.click lblface.visible = True 43. Private Sub btnany_click(...) Handles btnone.click, btntwo.click txtoutput.text = "You just clicked on a button."

18 Student Solutions Manual (Page 18 of 211) CHAPTER 3 EXERCISES Not valid 13. Valid 15. Not valid Private Sub btncompute_click(...) Handles btncompute.click lstoutput.items.add((7 * 8) + 5) 25. Private Sub btncompute_click(...) Handles btncompute.click lstoutput.items.add(0.055 * 20) 27. Private Sub btncompute_click(...) Handles btncompute.click lstoutput.items.add(17 * ( )) 29. x y Private Sub btnevaluate_click(...) Handles btnevaluate.click Dim x, y As Double 0 0 x = y = 3 * x 2 6 x = y lstresults.items.clear() 11 6 lstresults.items.add(x + 4) 11 6 y = y The third line should read c = a + b 41. The first assignment statement should not contain a comma. The second assignment statement should not contain a dollar sign W is not a valid variable name. 45. Dim quantity As Integer =

19 Student Solutions Manual (Page 19 of 211) 59. Private Sub btncompute_click(...) Handles btncompute.click Dim revenue, costs, profit As Double revenue = costs = profit = revenue - costs lstoutput.items.add(profit) 61. Private Sub btncompute_click(...) Handles btncompute.click Dim price, discountpercent, markdown As Double price = discountpercent = 30 markdown = (discountpercent / 100) * price price = price - markdown lstoutput.items.add(math.round(price, 2)) 63. Private Sub btncompute_click(...) Handles btncompute.click Dim balance As Double balance = 100 balance += 0.05 * balance balance += 0.05 * balance balance += 0.05 * balance lstoutput.items.add(math.round(balance, 2)) 65. Private Sub btncompute_click(...) Handles btncompute.click Dim balance As Double balance = 100 balance = balance * (1.05 ^ 10) lstoutput.items.add(math.round(balance, 2)) 67. Private Sub btncompute_click(...) Handles btncompute.click Dim acres, yieldperacre, corn As Double acres = 30 yieldperacre = 18 corn = yieldperacre * acres lstoutput.items.add(corn)

20 Student Solutions Manual (Page 20 of 211) 69. Private Sub btncompute_click(...) Handles btncompute.click Dim distance, elapsedtime, averagespeed As Double distance = 233 elapsedtime = 7-2 averagespeed = distance / elapsedtime lstoutput.items.add(averagespeed) 71. Private Sub btncompute_click(...) Handles btncompute.click Dim waterperpersonperday, people, days, waterused As Double waterperpersonperday = 1600 people = days = 365 waterused = waterperpersonperday * people * days lstoutput.items.add(waterused)