Computer Programming with GNU Smalltalk - Free

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Chapter 3 92 Computer Programming with GNU Smalltalk double quotes, consecutively or we might use single quotes if appropriate for reader. 4. We can do that with our current knowledge by writing every single number manually like: 1 printNl. 2 printNl. 3 printNl. . . . 998 printNl. 999 printNl 1000 printNl. But of course, this is not practical and nobody can force us to do that. Later on this book, we will learn about loops and see how we can achieve this task easily in just one line of code. If we imagine about it, we will probably come to a point that: "We should be able to define a range and make the printNl command act on that range.", which is the exact solution we will see. 5. Everything the computer generously give us is an output. It can be an image, a sound, a movement etc. So, actually, beside our monitor image which is in the form of a terminal text in this case, our speakers or a printer may also be classified as output devices. Also, keyboard is not the only input device. Every device which give us the opportunity to send information to the computer is an input device. For example, a mouse, a scanner, a web cam, a touch screen may all be specified as input devices. Programming languages usually give us to change standard input and output devices so that the computer and the user interacts with each other using different ways and GNU Smalltalk is not an exception. 1. An object is a unit which represents a thing in the program. It has some definitions how to respond to certain messages it receives from outside (usually from us or from other objects) which are called methods. We communicate with objects via messages we send to invoke the methods inside them. Classes are the templates of the objects we want to create. We first define a class, then produce objects from it. 2. Giving a name to an object is called assignment and we call this names variables in programming jargon. This is because although a name refers to only one object, the object it refers to can be changed any time. We need them to hold a data for later use in a program. The data might expected to be changing in different parts of a program so giving it a name would be easier for us instead of dealing with its
value, directly. Answers of Review Questions 93 3. Messages are classified as unary, binary and keyword messages. We can count reverse and asUppercase as examples of unary messages; count + and * as binary messages; count at:put: and removeKey: as keyword messages. 4. We can deal with natural numbers like 3, 10, 25; real numbers like 3.5, 8.2, 0.4e5 or fractions like 4/7, 8/13, 25/138. 5. 6. 7. "answer_3_5.st" | theNumber | Transcript show: 'Please enter a number to get its cube: '. theNumber := stdin nextLine. Transcript show: 'The cube of ', theNumber, ' is ', (theNumber asInteger squared * theNumber asInteger) printString, '.'; cr. Please enter a number to get its cube: 3 The cube of 3 is 27. "answer_3_6.st" | theNumbers arithmeticAverage | Transcript show: 'Please enter two numbers separated by space to get their arithmetic average: '. theNumbers := stdin nextLine tokenize: ' '. arithmeticAverage := ((theNumbers at: 1) asInteger + (theNumbers at: 2) asInteger) / 2. Transcript show: 'The arithmetic average of ', (theNumbers at: 1), ' and ', (theNumbers at: 2), ' is ', arithmeticAverage printString, '.'; cr. Please enter two numbers separated by space to get their arithmetic average: 10 20 The arithmetic average of 10 and 20 is 15. "answer_3_7.st" | definitions theWord |
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Computer Programming using GNU Smal
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To the ant I accidentally crushed y
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II We will often use this kind of b
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Contents Preface I Who is This Book
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Postface 107 About the Author......
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Chapter 1: Introduction to Programm
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Away f rom Hardware Easy -to-Mainta
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Introduction to Programming World 5
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like image viewer or PDF reader to
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Chapter 2: Introduction to GNU Smal
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Introduction to GNU Smalltalk 15 me
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Introduction to GNU Smalltalk 17 4.
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Objects, Messages and Classes: Part
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Unary, Binary and Keyword Messages
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Common Classes and Their Usage: Par
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setNumerator:setDenominator: Object
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Carl tellUsYourLastName Here Carl r
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aSet Set ('Soap' 'Toothbrush' ) Obj
Page 53 and 54: new We create a dictionary with new
Page 55 and 56: Objects, Messages and Classes: Part
Page 57 and 58: Chapter 4: Controlling the Flow of
Page 59 and 60: anObject ifTrue: [block-expression-
Page 61 and 62: Controlling the Flow of Execution 4
Page 63 and 64: ] This is the 1. line. This is the
Page 65 and 66: Controlling the Flow of Execution 5
Page 71 and 72: The general syntax for creating cla
Page 75 and 76: ourObjectName := SubclassName new O
Page 77 and 78: ] ] 'Woof!' printNl. Animal subclas
Page 79 and 80: Animal setAnimalNumber: 1. dog setN
Page 81 and 82: printString, ' years old.'; cr. ] ]
Page 83 and 84: me := Human new. me setName: 'Canol
Page 85 and 86: getAge [ ^age ] Objects, Messages a
Page 91 and 92: Chapter 6: What to Do Next How Can
Page 93 and 94: What to Do Next 81
Page 95 and 96: Installing Programming Environment
Page 97 and 98: ./configure make make install Insta
Page 99 and 100: Appendix B: ASCII Table Number (Dec
Page 101 and 102: Appendix C: Answers of Review Quest
Page 103: Chapter 2 Answers of Review Questio
Page 107 and 108: Answers of Review Questions 95 exam
Page 109 and 110: ]. Transcript cr. Answers of Review
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Page 113 and 114: setHonesty: rateOfHonesty [ "Honest
Page 115 and 116: Answers of Review Questions 103 of
Page 117 and 118: Alphabetical Index accessor 66 Argu
Page 119: Postface Postface 107 Now, we are a
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Computer Programming with GNU Smalltalk - Free

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