THE WAY TO GO - 示水的程序客栈

[Pages:629]THE WAY TO GO

A Thorough Introduction to the Go Programming Language

IVO BALBAERT

THE WAY TO GO

Also by Ivo Balbaert:

"Handboek Programmeren met Ruby en Rails.", 2009, Van Duuren Media, ISBN: 978-90-5940-365-9

THE WAY TO GO

A Thorough Introduction to the Go Programming Language

IVO BALBAERT

iUniverse, Inc.

Bloomington

The Way to Go A Thorough Introduction to the Go Programming Language

Copyright ? 2012 by Ivo Balbaert.

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ISBN: 978-1-4697-6916-5 (sc) ISBN: 978-1-4697-6917-2 (ebk)

Printed in the United States of America

iUniverse rev. date: 03/05/2012

CONTENTS

Preface................................................................................................................................ xix PART 1--WHY LEARN GO--GETTING STARTED Chapter 1--Origins, Context and Popularity of Go ..............................................................1

1.1 Origins and evolution ...............................................................................................1 1.2 Main characteristics, context and reasons for developing a new language...................4

1.2.1 Languages that influenced Go ........................................................................4 1.2.2 Why a new language? .....................................................................................5 1.2.3 Targets of the language ...................................................................................5 1.2.4 Guiding design principles ..............................................................................7 1.2.5 Characteristics of the language .......................................................................7 1.2.6 Uses of the language.......................................................................................8 1.2.7 Missing features? ............................................................................................9 1.2.8 Programming in Go .....................................................................................10 1.2.9 Summary .....................................................................................................10 Chapter 2--Installation and Runtime Environment ...........................................................11 2.1 Platforms and architectures ....................................................................................11 (1) The gc Go-compilers: .................................................................................11 (2) The gccgo-compiler: ...................................................................................13 (3) File extensions and packages: ......................................................................14 2.2 Go Environment variables .......................................................................................14 2.3 Installing Go on a Linux system ..............................................................................16 2.4 Installing Go on an OS X system ............................................................................21 2.5 Installing Go on a Windows system.........................................................................21 2.6 What is installed on your machine? ........................................................................26 2.7 The Go runtime ......................................................................................................27 2.8 A Go interpreter .....................................................................................................27

Chapter 3--Editors, IDE's and Other tools.........................................................................28 3.1 Basic requirements for a decent Go development environment................................28 3.2 Editors and Integrated Development Environments ................................................29 3.2.1. Golang LiteIDE .........................................................................................32 3.2.2. GoClipse.....................................................................................................33 3.3 Debuggers ...............................................................................................................34 3.4 Building and running go-programs with command- and Makefiles .........................35 3.5 Formatting code: go fmt or gofmt ...........................................................................39 3.6 Documenting code: go doc or godoc .......................................................................40 3.7 Other tools..............................................................................................................41 3.8 Go's performance ....................................................................................................41 3.9 Interaction with other languages..............................................................................43 3.9.1. Interacting with C ......................................................................................43 3.9.2. Interacting with C++...................................................................................45

PART 2--CORE CONSTRUCTS AND TECHNIQUES OF THE LANGUAGE Chapter 4--Basic constructs and elementary data types ......................................................49

4.1. Filenames--Keywords--Identifiers.........................................................................49 4.2. Basic structure and components of a Go-program ..................................................50

4.2.1 Packages, import and visibility .....................................................................51 4.2.3 Comments ...................................................................................................56 4.2.4 Types............................................................................................................57 4.2.5 General structure of a Go-program ..............................................................58 4.2.6 Conversions .................................................................................................60 4.2.7 About naming things in Go .........................................................................60 4.3. Constants ...............................................................................................................60 4.4. Variables.................................................................................................................63 4.4.1 Introduction ................................................................................................63 4.4.2 Value types and reference types ....................................................................66 4.4.3 Printing........................................................................................................68 4.4.4 Short form with the := assignment operator .................................................69 4.4.5 Init-functions...............................................................................................70 4.5. Elementary types and operators ..............................................................................73 4.5.1. Boolean type bool .......................................................................................73 4.5.2. Numerical types ..........................................................................................75 4.5.2.1 ints and floats............................................................................................75 4.5.2.2 Complex numbers ....................................................................................79 4.5.2.3 Bit operators .............................................................................................79 4.5.2.4 Logical operators.......................................................................................81

4.5.2.5 Arithmetic operators ................................................................................82 4.5.2.6 Random numbers .....................................................................................82 4.5.3. Operators and precedence ...........................................................................84 4.5.4. Aliasing types ..............................................................................................84 4.5.5. Character type ............................................................................................85 4.6. Strings ....................................................................................................................86 4.7. The strings and strconv package .............................................................................88 4.7.1--Prefixes and suffixes:..................................................................................88 4.7.2--Testing whether a string contains a substring:............................................89 4.7.3--Indicating at which position (index) a substring or character occurs

in a string: ..................................................................................................89 4.7.4--Replacing a substring: ...............................................................................90 4.7.5--Counting occurrences of a substring:.........................................................90 4.7.6--Repeating a string:.....................................................................................90 4.7.7--Changing the case of a string:....................................................................91 4.7.8--Trimming a string: ....................................................................................92 4.7.9--Splitting a string:.......................................................................................92 4.7.10--Joining over a slice: .................................................................................92 4.7.11--Reading from a string:.............................................................................93 4.8. Times and dates......................................................................................................95 4.9. Pointers ..................................................................................................................96 Chapter 5--Control structures..........................................................................................101 5.1--The if else construct ...........................................................................................101 5.2--Testing for errors on functions with multiple return values.................................106 5.3--The switch keyword ...........................................................................................110 5.4--The for construct ...............................................................................................114 5.4.1 Counter-controlled iteration ......................................................................114 Character on position 2 is: ..........................................................................................116 5.4.2 Condition-controlled iteration ..................................................................117 5.4.3 Infinite loops ............................................................................................118 5.4.4 The for range construct ..............................................................................119 5.5--Break / continue.................................................................................................121 5.6--Use of labels with break and continue--goto......................................................123 Chapter 6--Functions.......................................................................................................126 6.1 Introduction..........................................................................................................126 6.2 Parameters and return values .................................................................................129 6.2.1 Call by value / Call by reference .................................................................129 6.2.2 Named return variables ..............................................................................131

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