Sams Teach Yourself C in 24 Hours (3 page)

Workshop ............................................................................................................171

Quiz ................................................................................................................171

Exercises ........................................................................................................172

Part III Pointers and Arrays

173

Hour 11 Understanding Pointers

175

What Is a Pointer?................................................................................................176

Address (Left Value) Versus Content (Right Value) ............................................176

The Address-of Operator (&) ..........................................................................177

Declaring Pointers................................................................................................179

The Dereference Operator (*) ........................................................................182

Null Pointers ..................................................................................................183

Updating Variables via Pointers ..........................................................................183

Pointing to the Same Memory Location..............................................................184

Summary ..............................................................................................................186

Q&A ....................................................................................................................187

Workshop ............................................................................................................188

Quiz ................................................................................................................188

Exercises ........................................................................................................188

Hour 12 Understanding Arrays

189

What Is an Array? ................................................................................................190

Declaring Arrays ............................................................................................190

Indexing Arrays ..............................................................................................190

Initializing Arrays ..........................................................................................191

The Size of an Array............................................................................................192

Arrays and Pointers..............................................................................................194

Displaying Arrays of Characters ....................................................................196

The Null Character (‘\0’)..............................................................................198

Multidimensional Arrays ....................................................................................199

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Sams Teach Yourself C in 24 Hours

Unsized Arrays ....................................................................................................201

Summary ..............................................................................................................203

Q&A ....................................................................................................................203

Workshop ............................................................................................................204

Quiz ................................................................................................................204

Exercises ........................................................................................................205

Hour 13 Manipulating Strings

207

Declaring Strings ................................................................................................208

What Is a String? ............................................................................................208

Initializing Strings ..........................................................................................208

String Constants versus Character Constants ................................................209

How Long Is a String? ........................................................................................212

The strlen() Function ..................................................................................212

Copying Strings with strcpy()......................................................................213

Reading and Writing Strings ..............................................................................215

The gets() and puts() Functions..................................................................215

Using %s with the printf() Function ............................................................217

The scanf() Function ....................................................................................217

Summary ..............................................................................................................219

Q&A ....................................................................................................................220

Workshop ............................................................................................................221

Quiz ................................................................................................................221

Exercises ........................................................................................................221

Hour 14 Understanding Scope and Storage Classes

223

Hiding Data..........................................................................................................224

Block Scope....................................................................................................224

Nested Block Scope........................................................................................225

Function Scope ..............................................................................................226

Program Scope................................................................................................227

The Storage Class Specifiers ..............................................................................229

The auto Specifier ..........................................................................................229

The static Specifier ......................................................................................230

File Scope and the Hierarchy of Scopes ........................................................232

The register Specifier ..................................................................................233

The extern Specifier ......................................................................................233

The Storage Class Modifiers ..............................................................................234

The const Modifier ........................................................................................234

The volatile Modifier ..................................................................................235

Summary ..............................................................................................................236

Q&A ....................................................................................................................237

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Contents

xi

Workshop ............................................................................................................238

Quiz ................................................................................................................238

Exercises ........................................................................................................239

Part IV Functions and Dynamic Memory Allocation

241

Hour 15 Working with Functions

243

Declaring Functions ............................................................................................244

Declaration Versus Definition ........................................................................244

Specifying Return Types ................................................................................244

Using Prototypes ............................................................................................245

Making Function Calls ..................................................................................245

Prototyping Functions..........................................................................................247

Functions with No Arguments........................................................................248

Using time(), localtime(), and asctime()..................................................249

Functions with a Fixed Number of Arguments ..............................................251

Prototyping a Variable Number of Arguments ..............................................251

Processing Variable Arguments ......................................................................252

Learning Structured Programming ......................................................................255

Summary ..............................................................................................................255

Q&A ....................................................................................................................256

Workshop ............................................................................................................257

Quiz ................................................................................................................257

Exercises ........................................................................................................257

Hour 16 Applying Pointers

259

Pointer Arithmetic................................................................................................259

The Scalar Size of Pointers ............................................................................260

Pointer Subtraction ........................................................................................263

Pointers and Arrays..............................................................................................264

Accessing Arrays via Pointers........................................................................264

Pointers and Functions ........................................................................................266

Passing Arrays to Functions ..........................................................................266

Passing Pointers to Functions ........................................................................268

Passing Multidimensional Arrays as Arguments............................................270

Arrays of Pointers ................................................................................................272

Pointing to Functions ..........................................................................................274

Summary ..............................................................................................................276

Q&A ....................................................................................................................276

Workshop ............................................................................................................277

Quiz ................................................................................................................277

Exercises ........................................................................................................278

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Sams Teach Yourself C in 24 Hours

Hour 17 Allocating Memory

279

Allocating Memory at Runtime ..........................................................................280

The malloc() Function ........................................................................................280

Releasing Allocated Memory with free() ..........................................................283

The calloc() Function ........................................................................................286

The realloc() Function ......................................................................................288

Summary ..............................................................................................................291

Q&A ....................................................................................................................292

Workshop ............................................................................................................293

Quiz ................................................................................................................293

Exercises ........................................................................................................294

Hour 18 Using Special Data Types and Functions

295

The enum Data Type ............................................................................................296

Declaring the enum Data Type ........................................................................296

Assigning Values to enum Names ..................................................................296

Making typedef Definitions................................................................................300