(cid:36)(cid:80)(cid:78)(cid:81)(cid:83)(cid:70)(cid:73)(cid:70)(cid:79)(cid:84)(cid:74)(cid:87)(cid:70)(cid:2)(cid:51)(cid:86)(cid:67)(cid:90) (cid:49)(cid:83)(cid:80)(cid:72)(cid:83)(cid:66)(cid:78)(cid:78)(cid:74)(cid:79)(cid:72) (cid:40)(cid:80)(cid:2)(cid:71)(cid:83)(cid:80)(cid:78)(cid:2)(cid:67)(cid:70)(cid:72)(cid:74)(cid:79)(cid:79)(cid:70)(cid:83)(cid:2)(cid:85)(cid:80)(cid:2)(cid:68)(cid:80)(cid:79)(cid:96)(cid:69)(cid:70)(cid:79)(cid:85)(cid:2)(cid:81)(cid:83)(cid:80)(cid:72)(cid:83)(cid:66)(cid:78)(cid:78)(cid:70)(cid:83) Jordan Hudgens BIRMINGHAM - MUMBAI Comprehensive Ruby Programming Copyright © 2017 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: June 2017 Production reference: 1280617 (cid:49)(cid:86)(cid:67)(cid:77)(cid:74)(cid:84)(cid:73)(cid:70)(cid:69)(cid:2)(cid:67)(cid:90)(cid:2)(cid:49)(cid:66)(cid:68)(cid:76)(cid:85)(cid:2)(cid:49)(cid:86)(cid:67)(cid:77)(cid:74)(cid:84)(cid:73)(cid:74)(cid:79)(cid:72)(cid:2)(cid:45)(cid:85)(cid:69)(cid:16) (cid:45)(cid:74)(cid:87)(cid:70)(cid:83)(cid:90)(cid:2)(cid:49)(cid:77)(cid:66)(cid:68)(cid:70) (cid:21)(cid:23)(cid:2)(cid:45)(cid:74)(cid:87)(cid:70)(cid:83)(cid:90)(cid:2)(cid:52)(cid:85)(cid:83)(cid:70)(cid:70)(cid:85) (cid:35)(cid:74)(cid:83)(cid:78)(cid:74)(cid:79)(cid:72)(cid:73)(cid:66)(cid:78) (cid:35)(cid:21)(cid:2)(cid:20)(cid:49)(cid:35)(cid:14)(cid:2)(cid:54)(cid:44)(cid:16) ISBN 978-1-78728-064-9 Credits Author Copy Editor Jordan Hudgens Tom Jacob Project Coordinator Proofreader Suzanne Coutinho Safis Editing Acquisition Editor Indexer Ben Renow-Clarke Aishwarya Gangawane Content Development Editor Graphics Radhika Atitkar Kirk D'Penha Technical Editor Production Coordinator Bhagyashree Rai Arvindkumar Gupta About the Author Jordan Hudgens is the CTO and founder of DevCamp, where he leads instruction and curriculum development for all the DevCamp and Bottega code schools around the US. As a developer over the past decade, Jordan has traveled the world building applications and training individuals on a wide variety of topics, including Ruby development, big data analysis, and software engineering. Jordan focuses on project-driven education as opposed to theory-based development. This style of teaching is conducive to learning how to build real-world products that adhere to industry best practices. Additionally, Jordan has published multiple books on programming and computer science along with developing training curriculum for Learn.co, DevCamp, and AppDev on the topics, namely Ruby on Rails, Java, AngularJS, NoSQL, API development, and algorithms. www.PacktPub.com For support files and downloads related to your book, please visit (cid:88)(cid:88)(cid:88)(cid:16)(cid:49)(cid:66)(cid:68)(cid:76)(cid:85)(cid:49)(cid:86)(cid:67)(cid:16)(cid:68)(cid:80)(cid:78). Did you know that Packt offers eBook versions of every book published, with PDF and ePub files available? 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Table of Contents Preface 1 Chapter 1: Introduction to the Ruby Programming Language 8 What is Ruby? 9 Popular sites that use Ruby 9 Installing Ruby on a computer 9 Ruby language dashboard 10 Installing different Ruby versions with RVM 16 Summary 18 Chapter 2: Ruby Variables 19 Using variables in Ruby 19 Variable code implementation 20 Printing to the Ruby console 22 Using puts 22 Using p 22 Getting input from the Ruby console using gets and chomp 25 Code implementation 26 Variable scope and variable types 28 Local variables 29 Global variables 30 Instance variables 31 Constants 32 Class variables 32 Summary 33 Chapter 3: Ruby Strings 34 Using strings in Ruby 34 Missing quotation marks 35 Printing strings 36 Storing strings in variables 37 String interpolation guide for Ruby 37 What is string interpolation? 37 String manipulation guide 40 What is string manipulation? 40 String manipulation code examples 41 Method chaining 41 A practical implementation 42 Give it a bang! 42 String substitution guide 43 Adding a bang 45 Becoming a block head 46 Split, strip, and join guides for strings 47 Using the strip method 47 Using the split method 48 Using the join method 51 Summary 52 Chapter 4: Working with Numbers in Ruby 53 Integer arithmetic guide 53 Arithmetic order of operations 54 Difference between integers and floats 55 Summary 56 Chapter 5: Ruby Methods 57 Creating methods in Ruby 57 What does a Ruby method return? 60 What are the differences between class and instance methods in Ruby? 62 Ruby proc tutorial 67 Proc code example 67 What is a block? 70 The Ruby lambda tutorial 71 Stabby lambdas 72 What is the difference between procs and lambdas in Ruby? 72 Argument count 72 Return behavior 74 Guide to method arguments in Ruby 76 What are method arguments? 77 Method argument syntax 79 Method argument code examples 79 Named arguments 80 Default argument values 83 Using splat and optional arguments in Ruby methods 85 Traditional splat arguments 85 Keyword-based splat arguments 86 Optional arguments 88 Summary 90 [ ii ] Chapter 6: Ruby Iterators and Loops 91 The while loop guide 91 The while loop code example 91 The each iterator method tutorial 94 The each loop code example 94 The for...in loops tutorial 97 Looping over a hash 98 Nested iterator code example 98 Using the select method 102 Using the map method – part 1 106 The map method code example 107 Using the map method – part 2 110 Summing values in an array using the inject method 112 Summary 114 Chapter 7: Ruby Collections 115 Using arrays 115 Deleting items from arrays 117 Using push and pop for arrays 119 The Ruby hash tutorial 121 The hash code example 122 Deleting elements from a hash 125 Iterating over a hash for a key or value 126 Top hash methods in Ruby 128 Adding elements to a hash 129 Swapping keys and values 129 Merging hashes 130 Converting a hash into an array 131 Listing all keys 132 Listing all values 132 Summary 132 Chapter 8: Ruby Conditionals 134 The conditionals guide 134 Real-world use of conditionals 134 Code example of conditionals 135 Syntax for the unless conditional 135 Running Ruby files 135 The unless conditional code example 136 Nested if...else conditionals 139 [ iii ]