Learn to Program with Small Basic

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5 TextWindow.Pause() 6 7 TextWindow.WriteLine("A hungry man is an angry man.") 8 TextWindow.Pause() 9 10 TextWindow.WriteLine("Love your enemies. They hate that.") Listing 6-3: Demonstrating the Pause() method After showing the first wise saying (line 4), the program calls Pause() to give the user time to read it (line 5). This call displays “Press any key to continue . . .” and waits for the user to press a key. When the user presses a key, the program displays the next bit of wisdom (line 7) and pauses again (line 8). The program continues to do this until the last statement is executed. Add more wise sayings to this program, and then share it with someone! What if you want to display a statement other than “Press any key to continue . . . ,” such as “Press any key to see the next line of wisdom . . .”? Well, Small Basic provides you with the PauseWithoutMessage() method for this purpose. You can write a custom prompt using Write() or WriteLine() as usual, and then call PauseWithoutMessage() to wait for the user. Try it out. Replace the calls to Pause() in lines 5 and 8 of Listing 6-3 with these statements: TextWindow.WriteLine("Press any key to see the next line of wisdom...") TextWindow.PauseWithoutMessage() Your program runs the same way as before but uses a more descriptive prompt. Working with User Input Let’s put your new knowledge to use by writing a couple of programs that read input from a user, process the input, and display the output back to the user. Converting Fahrenheit to Celsius Next, you’ll create a program that converts a temperature from degrees Fahrenheit to degrees Celsius. The program prompts the user for the temperature in Fahrenheit and then converts it to Celsius using this formula: C = ( 5÷ 9) ×( F − 32) Run the program in Listing 6-4 several times to see how it works. To use the degree symbol, press and hold the alt key, type 248 on your numeric keypad, and then release the alt key. 1 ' Fahrenheit2Celsius.sb 2 TextWindow.Write("Enter a temperature in °F: ") 3 F = TextWindow.ReadNumber() Getting User Input 77
4 C = (5 / 9) * (F - 32) 5 C = Math.Round(C) ' Rounds to nearest integer 6 TextWindow.WriteLine(F + " °F = " + C + " °C") Listing 6-4: Converting Fahrenheit to Celsius First, the program prompts the user to enter a temperature. When they press enter, their input is assigned to the variable F. Your program then converts the value stored in F to Celsius and stores the result in variable C (which is all done in line 4). Next, the program uses Math.Round() on line 5 to take the current value of C, round it to the nearest integer, and store the rounded value in C, which replaces the old value of C. You’ll learn more about the Round() method in Chapter 7, but we use it here to make the program’s output easier to read. Finally, your program displays the output (line 6). TRY IT OUT 6-1 Try to guess what the following program does. Run it to check your answer: TextWindow.Write("How old are you? ") age = TextWindow.ReadNumber() TextWindow.WriteLine("In ten years, you'll be " + (age + 10)) TextWindow.WriteLine("Wow! You'll be so old!") Averaging Numbers Let’s write a program that finds the average of four numbers provided by the user. There are a couple of ways to do this; the first is to use five variables, as shown in Listing 6-5. 1 ' Avg1.sb 2 TextWindow.Write("Enter 4 numbers. ") 3 TextWindow.WriteLine("Press after each one:") 4 n1 = TextWindow.ReadNumber() 5 n2 = TextWindow.ReadNumber() 6 n3 = TextWindow.ReadNumber() 7 n4 = TextWindow.ReadNumber() 8 avg = (n1 + n2 + n3 + n4) / 4 9 TextWindow.WriteLine("Average = " + avg) Listing 6-5: Finding the average of four numbers Look at the output when we enter 10, 20, 15, and 25: Enter 4 numbers. Press after each one: 10 20 78 Chapter 6
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Learn to Program with Small Basic A
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Learn to Program with Small Basic A
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Brief Contents Foreword by Vijaye R
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Exploring Other Features. .........
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7 Empowering Programs with math 83
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12 building Graphical User Interfac
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Storing Records. ..................
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Foreword Computer programming is ma
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Acknowledgments This book represent
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Introduction Have you ever wondered
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• In Chapter 11: Event-Driven Pro
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1 Introducing Small Basic Bill Gate
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BASIC language that would help kids
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Toolbar Help Area Editor Surface Fi
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Then click the New button to open a
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Helping Hands: IntelliSense and Syn
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Programming Challenges If you get s
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The Parts of a Program Let’s expl
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The method’s name and a brief des
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5 + 7 12 Here’s the output of thi
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For example, to make the TextWindow
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TRY IT OUT 2-3 Now you have a chanc
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Programming Errors Just because a p
Page 51 and 52: 26 Chapter 2 4. Write a program tha
Page 53 and 54: In the system you use at school, po
Page 55 and 56: Drawing Shapes You can draw lots of
Page 57 and 58: Figure 3-6 shows what the output lo
Page 59 and 60: 22 GraphicsWindow.BrushColor = "Lig
Page 61 and 62: DrawText() takes three arguments. T
Page 63 and 64: GraphicsWindow provides two methods
Page 65 and 66: 6. Write a program that draws this
Page 68 and 69: 4 Using Variables Have you ever wan
Page 70 and 71: Try changing the value in karenBear
Page 72 and 73: These two ways of updating the scor
Page 74 and 75: Figure 4-2: How a variable is added
Page 76 and 77: TRY IT OUT 4-3 Write a program that
Page 78 and 79: Two Kinds of Data Programs use all
Page 80 and 81: 5 Drawing Shapes with Turtle Graphi
Page 82 and 83: Absolute Motion With absolute motio
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Page 86 and 87: GraphicsWindow.PenColor = "Red" Gra
Page 88 and 89: The For loop runs Turtle.Move(60) a
Page 90 and 91: y 5). For the hexagon (the polygon
Page 92 and 93: Creating Polygon Art Using Nested L
Page 94 and 95: Endless Graphics In Listing 5-10 yo
Page 96: Write a program to have the turtle
Page 99 and 100: Talking to the Computer Until now,
Page 101: Figure 6-2: The text window waiting
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Page 108 and 109: 7 Empowering Programs with Math If
Page 110 and 111: Here’s a sample run of our progra
Page 112 and 113: Round() -4 -3.5 -3 0 3 3.5 4 Round(
Page 114 and 115: This code snippet shows you some ex
Page 116 and 117: Let’s walk through this program l
Page 118 and 119: Trigonometric Methods Trigonometric
Page 120: Programming Challenges If you get s
Page 123 and 124: Small Basic uses a few different wa
Page 125 and 126: You can test all sorts of condition
Page 127 and 128: Small Basic first finds the value o
Page 129 and 130: Your mom’s instructions assume th
Page 131 and 132: But wait, your mom just realized th
Page 133 and 134: This code asks the user to enter a
Page 136 and 137: 9 Using Decisions to Make Games Som
Page 138 and 139: Condition 1 True Statement set 1 If
Page 140 and 141: This change to the program means th
Page 142 and 143: Door 1 Door 2 Door 3 Figure 9-6: Pe
Page 144 and 145: Listing 9-4 shows an example of usi
Page 146 and 147: Think of the Shapes object as a “
Page 148 and 149: Background image (Grid.png) Star.pn
Page 150 and 151: In Figure 9-8, you see that the gri
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This code asks the player to enter
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10 Solving Problems with Subroutine
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Gulliver later learned that 1 glum-
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TRY IT OUT 10-1 When Gulliver asked
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variables that belong to the main p
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4 TextWindow.WriteLine("Your turn.
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1 step away). If the arrow hits the
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Then you set the graphics window’
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24 Shapes.SetText(msgText, "") 25 T
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Step 8: Shoot Arrows with ShootArro
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Lines 3-7 animate the dragon’s fi
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11 Event-Driven Programming So far,
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GraphicsWindow Events Let’s start
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4 5 Sub OnKeyDown 6 GraphicsWindow.
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13 Else 14 GraphicsWindow.DrawText(
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Useful Tips Before moving on, we’
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21 GraphicsWindow.BrushColor = "Red
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4 XG = Math.GetRandomNumber(8) - 1
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Programming Challenges If you get s
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Today, most programs use a graphica
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located at (100, 100). By default,
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9 GraphicsWindow.MouseMove = OnMous
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Let’s look at the computations. Y
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You start by loading the two backgr
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(line 8). If the total resistance i
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TRY IT OUT 12-4 Write a program to
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13 Repeating For Loops Have you eve
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Each For loop starts with the keywo
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The program uses a variable named s
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TRY IT OUT 13-5 What does the follo
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Nested Loops The statements in the
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Figure 13-7: The output of Stamp.sb
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2. Although the pizza in the previo
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In this chapter, you’ll learn how
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Note Although it’s not required b
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asks the user for the correct answe
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to become a value other than 0 (thi
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Step 4: Announce the Winner The las
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15 Grouping Data in One-Dimensional
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One way to think of an array is as
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The string initializer lets you fil
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TextWindow.WriteLine("Enter 5 numbe
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how much money was rescued from eac
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To create this program, we’ll use
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The apples fall from the trees. Usi
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The subroutine uses a For loop to c
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9 If ((xdiff < 20) And (ydiff < 20)
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4. Open the file USMapQuiz_Incomple
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Associative Arrays In the previous
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The expression If("ernie" = "Ernie"
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Here’s the output from a sample r
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The ContainsIndex() method takes tw
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Figure 16-1 shows the user interfac
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1 Sub OnButtonClicked 2 GraphicsWin
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17 Expanding to Higher-Dimension Ar
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1 ' Random2DArray.sb 2 For r = 1 To
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Animated Squares Let’s write a pr
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12 TextWindow.Write("Enter student
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(line 8). Line 9 displays Scott's M
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You start by initializing the sum v
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4 For col = 1 To 4 ' For each colum
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note If you run into any problems,
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First, you set all the elements of
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11 If ((rowP < 1) Or (rowP > 10) Or
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Open the file Okla.sb from this cha
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(both uppercase and lowercase), dig
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Taking Strings Apart: Substrings Ju
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two arguments: the source string th
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Here’s an output example: Who's y
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More on Code Points The Unicode cod
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Line 7 gets the Nth character of th
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Igpay Atinlay Let’s teach the com
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17 TextWindow.WriteLine("Good Job!"
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9 pos = Math.GetRandomNumber(len) '
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When you continue with the second a
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TRY IT OUT 18-10 Use the techniques
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19 Receiving File Input and Output
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and their meanings. File extensions
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program’s folder (right-click the
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in the file would run together in o
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Let’s experiment with the first p
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line number. As with the WriteLine(
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WARNING If the destination path poi
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6 For N = 1 To count ' Displays the
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wizard asks the user to perform. Th
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Figure 19-8 shows a sample run of t
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Where to Go from Here So you’ve m
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Index Numbers and Symbols 3DArrayDe
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squares, 31-32 star, 65-66 triangle
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integrated development environment
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parts of, 14-16 publishing, 5-6 run
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NewGame() subroutine, 255-256 OnBut
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ages 10 and up “Welcome to the ma
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