book

21st Century C, 2nd Edition

by Ben Klemens

October 2014

Intermediate to advanced

408 pages

10h 19m

English

O'Reilly Media, Inc.

Book available

Read now

Unlock full access

C Is Punk RockQ & A (Or, the Parameters of the Book)Standards: So Many to Choose FromThe POSIX StandardSome LogisticsThe Second EditionConventions Used in This BookUsing Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
Use a Package ManagerCompiling C with WindowsPOSIX for WindowsCompiling C with POSIXCompiling C Without POSIXWhich Way to the Library?A Few of My Favorite FlagsPathsRuntime LinkingUsing MakefilesSetting VariablesThe RulesUsing Libraries from SourceUsing Libraries from Source (Even if Your Sysadmin Doesn’t Want You To)Compiling C Programs via Here DocumentInclude Header Files from the Command LineThe Unified HeaderHere DocumentsCompiling from stdin
Using a DebuggerA Debugging Detective StoryGDB VariablesPrint Your StructuresUsing Valgrind to Check for ErrorsUnit TestingUsing a Program as a LibraryCoverageError CheckingWhat is the User’s Involvement in the Error?The Context in Which the User is WorkingHow Should the Error Indication Be Returned?Interweaving DocumentationDoxygenLiterate Code with CWEB
The ShellReplacing Shell Commands with Their OutputsUse the Shell’s for Loops to Operate on a Set of FilesTest for FilesfcMakefiles vs. Shell ScriptsPackaging Your Code with AutotoolsAn Autotools DemoDescribing the Makefile with Makefile.amThe configure Script
Changes via diffGit’s ObjectsThe StashTrees and Their BranchesMergingThe RebaseRemote Repositories
Dynamic LoadingThe Limits of Dynamic LoadingThe ProcessWriting to Be Read by NonnativesThe Wrapper FunctionSmuggling Data Structures Across the BorderLinkingPython HostCompiling and LinkingThe Conditional Subdirectory for AutomakeDistutils Backed with Autotools
Automatic, Static, and Manual MemoryPersistent State VariablesPointers Without mallocStructures Get Copied, Arrays Get Aliasedmalloc and Memory-TwiddlingThe Fault Is in Our StarsAll the Pointer Arithmetic You Need to KnowTypedef as a teaching tool
Don’t Bother Explicitly Returning from mainLet Declarations FlowSet Array Size at RuntimeCast LessEnums and StringsLabels, gotos, switches, and breaksgoto ConsideredswitchDeprecate FloatComparing Unsigned IntegersSafely Parse Strings to Numbers

Cultivate Robust and Flourishing MacrosThe PreprocessorTest MacrosHeader GuardsLinkage with static and externExternally Linked Variables in Header FilesThe const KeywordNoun-Adjective FormTensionDepthThe char const ** Issue
Making String Handling Less Painful with asprintfSecurityConstant StringsExtending Strings with asprintfA Pæan to strtokUnicodeThe Encoding for C CodeUnicode LibrariesThe Sample Code
Compound LiteralsInitialization via Compound LiteralsVariadic MacrosSafely Terminated ListsMultiple ListsForeachVectorize a FunctionDesignated InitializersInitialize Arrays and Structs with ZerosTypedefs Save the DayA Style NoteReturn Multiple Items from a FunctionReporting ErrorsFlexible Function InputsDeclare Your Function as printf-StyleOptional and Named ArgumentsPolishing a Dull FunctionThe Void Pointer and the Structures It Points ToFunctions with Generic InputsGeneric Structures
Extending Structures and DictionariesImplementing a DictionaryC, with fewer seamsFunctions in Your StructsVtablesScopePrivate Struct ElementsOverload_GenericCount ReferencesExample: A Substring ObjectExample: An Agent-Based Model of Group FormationConclusion
The EnvironmentThe IngredientsOpenMPCompiling OpenMP, pthreads, and C atomsInterferenceMap-reduceMultiple TasksThread LocalLocalizing Nonstatic VariablesShared ResourcesAtomsPthreadsC atomsAtomic structs
GLibPOSIXParsing Regular ExpressionsUsing mmap for Gigantic Data SetsThe GNU Scientific LibrarySQLiteThe Querieslibxml and cURL
The StructureC requires a compilation step, which consists of running a single commandThere’s a standard library, and it’s part of your operating systemThere’s a preprocessorThere are two types of commentThere is no print keywordVariable DeclarationsVariables have to be declaredEven functions have to be declared or definedBasic types can be aggregated into arrays and structsNew structure types can be definedYou can find out how much space a type takesThere is no special string typeExpressionsThe scoping rules for C are very simpleThe main function is specialMost of what a C program actually does is evaluate expressionsFunctions are evaluated using copies of the inputsExpressions are delimited by semicolonsThere are many shortcuts for incrementing or scaling a variableC has an expansive definition of truthDividing two integers always produces an integerC has a trinary conditional operatorBranching and looping expressions are not very different from any other languageThe for loop is just a compact version of the while loopPointersYou can directly request a block of memoryArrays are just blocks of memory; any block of memory can be used like an arrayA pointer to a scalar is really just a one-item arrayThere is a special notation for elements of pointed-to structsPointers let you modify function inputsEverything is somewhere, so everything can be pointed to

Content preview from 21st Century C, 2nd Edition

Preface

Is it really punk rock

Like the party line?

Wilco, “Too Far Apart”

C Is Punk Rock

C has only a handful of keywords and is a bit rough around the edges, and it rocks. You can do anything with it. Like the C, G, and D chords on a guitar, you can learn the basic mechanics quickly, and then spend the rest of your life getting better. The people who don’t get it fear its power and think it too edgy to be safe. By all rankings, it is consistently the most popular language that doesn’t have a corporation or foundation spending money to promote it.¹

Also, the language is about 40 years old, which makes it middle-aged. It was written by a few guys basically working against management—the perfect punk rock origins—but that was in the 1970s, and there’s been a lot of time for the language to go mainstream.

What did people do when punk rock went mainstream? In the decades since its advent in the 1970s, punk certainly has come in from the fringes: The Clash, The Offspring, Green Day, and The Strokes sold millions of albums worldwide (to name just a few), and I have heard lite instrumental versions of songs from the punk spinoff known as grunge at my local supermarket. The former lead singer of Sleater-Kinney now has a popular sketch comedy show that frequently lampoons punk rockers.² One reaction to the continuing evolution would be to take the hard line and say that the original wave was punk and everything else is just easy punk pop for the masses. The traditionalists can still ...