Learn to Program with Small Basic

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Endless Graphics In Listing 5-10 you created patterns by rotating a single polygon. You can also create patterns using two or more polygons of different sizes. To keep the code simple, let’s draw two polygons of different sizes and rotate them. Run the program shown in Listing 5-11 to see what patterns you can make. 1 ' PolygonArt.sb 2 Turtle.Speed = 10 3 numSides = 6 ' Set to 3 (triangle), 4 (square)... 4 repeatCount = 8 ' How many times to rotate 5 sideLen1 = 30 ' Side length of polygon 1 6 sideLen2 = 40 ' Side length of polygon 2 7 8 For I = 1 To repeatCount 9 For J = 1 To numSides ' Draws the first polygon 10 Turtle.Move(sideLen1) 11 Turtle.Turn(360 / numSides) 12 EndFor 13 14 For J = 1 To numSides ' Draws the second polygon 15 Turtle.Move(sideLen2) 16 Turtle.Turn(360 / numSides) 17 EndFor 18 19 ' Turns the turtle to prepare for the next round 20 Turtle.Turn(360 / repeatCount) 21 EndFor Listing 5-11: Rotating two similar polygons Figure 5-18 shows the output of this program. This program rotates two hexagons (the first has a side length of 30, and the second has a side length of 40) eight times. The outer loop in line 8 repeats up to the number in repeatCount. Each time the program loops, the code performs three actions: 1. Draw the first polygon using the side length in sideLen1 (lines 9–12). 2. Draw the second polygon using the side length in sideLen2 (lines 14–17). Figure 5-18: The output of PolygonArt.sb 3. Turn the turtle to get ready for the next round of the loop (line 20). Now try using the repeatCount values in Figure 5-19 to create lots of different patterns. Try setting sideLen1 = 40 and sideLen2 = 60! Drawing Shapes with Turtle Graphics 69
Using triangle with repeatCount = 12 Using square with repeatCount = 10 Using pentagon with repeatCount = 10 Using hexagon with repeatCount = 6 Using hexagon with repeatCount = 8 Using octagon with repeatCount = 8 Figure 5-19: Some of the patterns you can create by experimenting with PolygonArt.sb Experiment with this program to see what other shapes you can discover! TRY IT OUT 5-5 Change Listing 5-11 to draw three polygons (instead of two) of different sizes, and then rotate them. Save your discoveries for your next art gallery. (Or, if you don’t want to become a millionaire, go to http://tiny.cc/turtlepatterns/ and share them with the world!) Programming Challenges If you get stuck, check out http://nostarch.com/smallbasic/ for the solutions and for more resources and review questions for teachers and students. 1. This code draws a circle: For K = 1 To 36 Turtle.Move(6) Turtle.Turn(10) EndFor 70 Chapter 5
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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
Page 43 and 44: 5 + 7 12 Here’s the output of thi
Page 45 and 46: For example, to make the TextWindow
Page 47 and 48: TRY IT OUT 2-3 Now you have a chanc
Page 49 and 50: 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
Page 84 and 85: North 0 (360) 315 (-45) 45 (-315) W
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 96: Write a program to have the turtle
Page 99 and 100: Talking to the Computer Until now,
Page 101 and 102: Figure 6-2: The text window waiting
Page 103 and 104: 4 C = (5 / 9) * (F - 32) 5 C = Math
Page 105 and 106: 9 noun = TextWindow.Read() 10 11 Te
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
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Listing 9-4 shows an example of usi
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Think of the Shapes object as a “
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Background image (Grid.png) Star.pn
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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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Learn to Program with Small Basic

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