Learn to Program with Small Basic

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2 Getting Started Now we’ll walk through some code step-by-step, so you can learn about the important pieces. As you read, enter the examples, and we’ll explain how to run them and modify them. But don’t stop there: experiment to give your programs a personal touch. We’ve included exercises at the end of each section to help you become a programming master (like a Jedi, but without the dangerous lightsabers). Try out the exercises to hone your skills.
The Parts of a Program Let’s explore the different parts of a program by looking at a simple example. Listing 2-1 shows a program similar to the Greetings.sb program you wrote in Chapter 1. Enter this program into the Small Basic Editor, and then click the Run button on the Toolbar (or press F5 on your keyboard) to run it. 1 ' Welcome.sb 2 TextWindow.WriteLine("Welcome to Small Basic.") Listing 2-1: Writing a welcome message These two lines are the source code of your Welcome.sb program. When you run this code, you’ll see an output window that looks like Figure 2-1. (Note that the window’s title shows where we saved the file, so yours could be different.) Figure 2-1: The output window for Welcome.sb Note Your console window will look slightly different from this one, since the window has a black background by default. For the rest of the book, we’ll show the output as text, except when it’s necessary to see the window. Small Basic automatically adds the text Press any key to continue... to the window to give you a chance to view the output (there isn’t an any key on your keyboard, so don’t look for it). Otherwise, the screen would flash your output and disappear. Comments and Statements The line that starts with a single quote (') is called a comment. You can add comments to explain what your program does, and Small Basic just ignores them. The comment on line 1 is the name of the file that contains your source code. Note You should get into the habit of commenting your code, because you’ll often head to the forums or to friends for help, and they’ll need to understand what your code is trying to do. The Small Basic Editor shows all comments in green so you can easily tell them apart from lines of actual code, which are called statements. Comments make programs easier to read, and you can add them anywhere! But be 14 Chapter 2
Page 1 and 2: Learn to Program with Small Basic A
Page 4 and 5: Learn to Program with Small Basic A
Page 6: Brief Contents Foreword by Vijaye R
Page 9 and 10: Exploring Other Features. .........
Page 11 and 12: 7 Empowering Programs with math 83
Page 13 and 14: 12 building Graphical User Interfac
Page 15 and 16: Storing Records. ..................
Page 18 and 19: Foreword Computer programming is ma
Page 20 and 21: Acknowledgments This book represent
Page 22 and 23: Introduction Have you ever wondered
Page 24 and 25: • In Chapter 11: Event-Driven Pro
Page 26 and 27: 1 Introducing Small Basic Bill Gate
Page 28 and 29: BASIC language that would help kids
Page 30 and 31: Toolbar Help Area Editor Surface Fi
Page 32 and 33: Then click the New button to open a
Page 34 and 35: Helping Hands: IntelliSense and Syn
Page 36: Programming Challenges If you get s
Page 41 and 42: 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
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The For loop runs Turtle.Move(60) a
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y 5). For the hexagon (the polygon
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Creating Polygon Art Using Nested L
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Endless Graphics In Listing 5-10 yo
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Write a program to have the turtle
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Talking to the Computer Until now,
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Figure 6-2: The text window waiting
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4 C = (5 / 9) * (F - 32) 5 C = Math
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9 noun = TextWindow.Read() 10 11 Te
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7 Empowering Programs with Math If
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Here’s a sample run of our progra
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Round() -4 -3.5 -3 0 3 3.5 4 Round(
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This code snippet shows you some ex
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Let’s walk through this program l
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Trigonometric Methods Trigonometric
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Programming Challenges If you get s
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Small Basic uses a few different wa
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You can test all sorts of condition
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Small Basic first finds the value o
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Your mom’s instructions assume th
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But wait, your mom just realized th
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This code asks the user to enter a
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9 Using Decisions to Make Games Som
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Condition 1 True Statement set 1 If
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This change to the program means th
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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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