Learn to Program with Small Basic

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3 lwrCase = Text.ConvertToLowerCase(var1) ' lwrCase = "ewok" 4 TextWindow.WriteLine(lwrCase) ' Displays: ewok 5 TextWindow.WriteLine(var1) ' Displays: Ewok 6 uprCase = Text.ConvertToUpperCase(var1) ' uprCase = "EWOK" 7 TextWindow.WriteLine(uprCase) ' Displays: EWOK 8 TextWindow.WriteLine(var1) ' Displays: Ewok Listing 18-1: Changing the case of a string The call to ConvertToLowerCase() on line 3 returns the lowercase string "ewok", which is displayed on line 4. The statement on line 5 shows that the original string isn’t affected by the lowercase conversion; calling ConvertToLowerCase() returns a brand-new string whose characters are lowercase. The ConvertToUpperCase() method on line 6 returns the uppercase version of "EWOK", which is displayed on line 7. And line 8 also shows that the original string isn’t affected by the conversion. You can use these methods to make case-insensitive string comparisons. For example, let’s say your program asks a user about their favorite Shrek character. If the user likes Donkey, they win 200 points; otherwise, they win 100 points. The user can enter donkey, DONKEY, Donkey, DOnkey, or any other combination of cases in response to the question. Rather than checking for all the possible combinations, you can convert the user’s response to uppercase (or lowercase) and compare the result with that new string "DONKEY" (or "donkey" if you’re using lowercase). Run the program in Listing 18-2. 1 ' StringMatch.sb 2 While ("True") 3 TextWindow.Write("Who's your favorite Shrek character? ") 4 name = Text.ConvertToUpperCase(TextWindow.Read()) 5 If (name = "DONKEY") Then 6 TextWindow.WriteLine("You won 200 ogre points!") 7 Else 8 TextWindow.WriteLine("You won 100 ogre points!") 9 EndIf 10 EndWhile Listing 18-2: Case-insensitive string matching The Read() method on line 4 reads the text entered by the user. The user’s text is then converted to uppercase, and the result is stored in the name variable. Note how we used the Read() method directly as an argument to ConvertToUpperCase(); this is equivalent to the following two statements: name = TextWindow.Read() name = Text.ConvertToUpperCase(name) The If statement on line 5 compares the uppercase version of the user’s input with the literal string "DONKEY" and awards the user accordingly. Advanced Text Magic 269
Here’s an output example: Who's your favorite Shrek character? dOnkey You won 200 ogre points! TRY IT OUT 18-3 Write a program that prompts the user with a yes/no question, such as “Can you paint with all the colors of the wind?” Create a program that accepts y, yes, n, or no using any casing as valid answers. If the answer is invalid, ask the user to re-enter their answer. Character Coding with Unicode All computer data (including text) is stored as binary sequences of 0s and 1s. The letter A for example is 01000001. The mapping between a character and its binary representation is called encoding. Unicode is a universal encoding scheme that lets you encode more than a million characters from many languages. Each character is assigned a unique number (called a code point). For example, the code point for the character A is 65, and the code point for the dollar sign ($) is 36. The GetCharacterCode() method returns a character’s code point. But the GetCharacter() method does the opposite; when you give it a character’s code point, it returns the corresponding character. Run the program in Listing 18-3. 1 ' CharCode.sb 2 str = "ABab12" 3 For N = 1 To Text.GetLength(str) 4 ch = Text.GetSubText(str, N, 1) ' Gets the Nth character 5 code = Text.GetCharacterCode(ch) ' Gets its code point 6 TextWindow.WriteLine(ch + ": " + code) ' Displays ch and its code point 7 EndFor Listing 18-3: Demonstrating the GetCharacterCode() method Line 2 defines a string that contains six characters. Line 3 starts a For loop that accesses each of these characters; GetLength() sets the upper limit of the loop. Each iteration of the loop reads one character from the string and saves it in a variable named ch (line 4). Then the loop gets the Unicode code point for that character and saves it in the code variable (line 5). Line 6 displays the character and its code point. When you run this program, you’ll see the following output: A: 65 B: 66 270 Chapter 18
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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
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26 Chapter 2 4. Write a program tha
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In the system you use at school, po
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Drawing Shapes You can draw lots of
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Figure 3-6 shows what the output lo
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22 GraphicsWindow.BrushColor = "Lig
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DrawText() takes three arguments. T
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GraphicsWindow provides two methods
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6. Write a program that draws this
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4 Using Variables Have you ever wan
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Try changing the value in karenBear
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These two ways of updating the scor
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Figure 4-2: How a variable is added
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TRY IT OUT 4-3 Write a program that
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Two Kinds of Data Programs use all
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5 Drawing Shapes with Turtle Graphi
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Absolute Motion With absolute motio
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North 0 (360) 315 (-45) 45 (-315) W
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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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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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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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Page 246 and 247: The subroutine uses a For loop to c
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Page 259 and 260: The ContainsIndex() method takes tw
Page 261 and 262: Figure 16-1 shows the user interfac
Page 263 and 264: 1 Sub OnButtonClicked 2 GraphicsWin
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Page 268 and 269: 1 ' Random2DArray.sb 2 For r = 1 To
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Page 274 and 275: (line 8). Line 9 displays Scott's M
Page 276 and 277: You start by initializing the sum v
Page 278 and 279: 4 For col = 1 To 4 ' For each colum
Page 280 and 281: note If you run into any problems,
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Page 286: Open the file Okla.sb from this cha
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Page 303 and 304: 17 TextWindow.WriteLine("Good Job!"
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Page 307 and 308: When you continue with the second a
Page 309 and 310: TRY IT OUT 18-10 Use the techniques
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Page 330 and 331: Figure 19-8 shows a sample run of t
Page 332 and 333: Where to Go from Here So you’ve m
Page 334 and 335: Index Numbers and Symbols 3DArrayDe
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Page 338 and 339: integrated development environment
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ages 10 and up “Welcome to the ma
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