Visual C++ Object-Oriented Programming

Transcription

1 Visual C++ Object-Oriented Programming A Mark Andrews SAMS PUBLISHING A Division of Prentice Hall Computer Publishing 201 West 103rd Street, Indianapolis, Indiana, USA

2 Contents Introduction xxvii Part I Visual C++ 1 Microsoft Visual C++ 3 About Visual C++ 4 Other Visual C++ Features 5 The Visual Workbench Editor 7 The Standard and Professional Editions 10 Installing Visual C++ 12 What You Need to Install Visual C++ 12 One-Step and Multi-Step Installation 13 The Visual Workbench 13 Using Visual C++ 15 Writing a Visual C++ Program 16 About QuickWin 17 Visual C++ Projects 18 Building a Sample QuickWin Program 19 Summary 23 2 A Better С Plus 25 A Brief History of C++ 26 Learning C++ 27 C++ Comments 31 A Better Way 32 Mixing C-Style and C++-Style Comments 33 Keywords 34 C++ Keywords: The Complete List 34 Keywords Not Implemented in Visual C++ 38 Keywords Unique to Visual C++ 40 Identifiers 43 Data Types 44 Classes 45 char Types 45 Integer Types 46 Floating-Point Types 46 Aggregate Types 47 Structures 52

3 Visual C++ Object-Oriented Programming Unions 56 Pointer Types 60 Reference Types 60 Type void 61 The typedef Declaration 64 Summary 65 3 Type Qualifiers 67 The const Qualifier 68 Uses of the const Qualifier 68 const Objects in С and C++ 69 Advantages of Using const Objects 70 Enhancements to const Objects 70 New Features of const Objects 71 Initializing a const with a Function 72 Functions That Return const Objects 72 Passing a const Array to a Function 73 How the const Modifier Works 73 Altering the Linkage of a const Object 74 Using a const in a Pointer Declaration 75 Using Constants with Pointers 76 When Is a const Not a const? 76 Pointing to the Address of a const 77 Where to Put a const 77 A const Pointer to a const Object 78 The volatile Qualifier 78 How volatile Works 79 Declaring an Object to Be Both const and volatile 80 Summary 80 4 Variables 83 Declaring Variables in C++ 84 Initialization and Assignment 86 Initializing Constants and References 86 Initializing a Reference 86 Initializing a const 87 Initializing External Data 87 Function-Style Initializations 88 References 91 Defining a Reference 92 Capabilities of References 94 Initializing References 95

4 Contents References as Aliases 96 Passing References as Parameters to Functions 99 Passing an Argument by Value 99 Passing an Argument by Address 101 Passing an Argument by Reference 102 How Not to Use References 103 Accessing Elements of a Referenced Structure 104 Writing a Function That Returns a Reference 105 Using References with const Objects 107 Summary Properties of Variables 109 Storage Class 110 The External Storage Class 110 The Static Storage Class Ill Scope 114 Local Scope 114 Function Scope 116 File Scope 116 Prototype Scope 117 Resolving Conflicts in Names of Identifiers 117 How Scope Precedence Works 118 The Point of Declaration 119 The Scope Resolution Operator 119 Duration 120 Linkage 121 Internal Linkage 121 External Linkage 121 No Linkage 122 Summary Functions 125 The main() Function 126 Defining a Function 128 C++-Style Function Definitions 130 Function Prototypes 131 An Example of Function Prototyping 131 Rules for Function Prototyping 132 Overloading Functions 133 Using Function Overloading 134 Name Mangling 135 Inline Functions 136

5 Visual C++ Object-Oriented Programming Default Function Arguments 137 Variable Argument Lists 139 Variable Argument Lists in С 139 Variable Argument Lists in C Writing Variable Argument Lists 140 The STDARG.H Functions 142 Passing Arguments to Functions 145 Safeguarding Data Passed to a Function 146 Declaring an Argument to Be a Constant 146 Calling a Function to Initialize a const 147 Summary Compiling Visual C++Programs 151 Building a Visual C++ Program 152 Compiling a Visual C++ Program 154 Speeding Up Compilation 154 Using Precompiled Files 154 Using the Fast Compile Option 155 Using a Disk-Caching Program 155 Use a RAM Disk Program 155 Identifiers 156 Compiling Programs in P-Code 156 С and C++ Compilers 157 Compiling Programs with the Visual Workbench 158 The New Project Dialog Box 159 QuickWin Programs and Other Applications 161 The Project Options Dialog Box 161 Configuring Your System for Command-Line Compilation 165 The Visual C++ Preprocessor 167 Header Files 170 Using Header Files 170 Contents of Header Files 171 Nesting Header Files 172 Bracketed and Quoted #include Directives 172 How the Preprocessor Finds Header Files 172 Precompiled Headers and Precompiled Files 174 The#define Directive 176 Creating Constants with #define 176 What the #define Directive Doesn't Do 177 Creating Macros with #define 178

6 Contents Conditional Compilation Directives 181 Writing Comments with Compilation Directives 182 The #if Directive 182 The #else and #elif Directives 183 Combining the #ifdef and #else Directives 184 Other Preprocessor Directives 185 Special Features of the Visual C++ Preprocessor 186 Charizing 186 Stringizing 187 Token Concatenation 188 Trigraph Replacement 190 Predefined Macros 191 Summary Linking Visual C++Programs 195 Creating a Project 196 The Linker Button 197 Using the Linker Options Dialog Box 197 Getting Help with Command-Line Options 199 Linking a C++ Program 199 Libraries Provided with Visual C Mixing C++ with Other Languages 202 Name Mangling 203 Alternate Linkage Specifications 203 The extern Keyword 204 Effects of Linkage Specifications 205 Function Modifiers 206 The С Calling Convention 207 The Pascal/FORTRAN Calling Convention 208 The Register Calling Convention 210 The asm Modifier Managing Memory 213 About This Chapter 214 Segmented Memory 215 How Segmented Memory Works 216 Memory Segments and Paragraph Boundaries 217 The 80X86 Chip's Segment Registers 217 Near Calls and Far Calls 218 How Segments Overlap 219 SegmentOffset Addressing 219 Memory Modes 219

7 -j. Visual C++ Object-Oriented Programming Real Mode 220 Protected Mode 220 Standard Mode and Enhanced Mode 221 Standard Mode 222 Enhanced Mode 222 Memory Models 223 How Memory Models Work 223 Memory Models and Pointers 224 Overlays and the MOVE Utility 225 Deciding on a Memory Model 226 Advantages of Using Memory Models 227 The Six Memory Models 227 The Tiny Memory Model 227 The Small Memory Model 228 The Medium Memory Model 229 The Compact Memory Model 229 The Large Memory Model 229 The Huge Memory Model 229 Using Pointers in Visual C near Pointers 230 far Pointers 231 huge Pointers 232 Pointers to void 232 Pointers to Undeclared Data Types 233 The new and delete Operators 233 How the new Operator Works 234 Initializing Memory with a Value 235 Using the new Operator 236 Allocating Memory for an Array 237 Allocating Memory Interactively 238 Allocating Memory for an Array of Unknown Size 239 Deallocating Memory Assigned to Arrays 239 Allocating Memory by Calling a Function 240 Using the delete Operator 242 The _set_new_handler() Function 243 How new Allocates Memory 245 The Near, Far, and Based Memory Spaces 245 Overloading the new and delete Operators 246 The operator new() and operator delete() Functions 246 The size_ttype 248

8 Adding Parameters to the new Operator 248 Using new to Change Memory Pools 250 Overloading _set_new_handler() 250 Saving and Restoring a New Handler 251 Returning _set_new_handler() to Its Default Behavior 252 Alternate _set_new_handler() Functions 252 Memory Management Under Windows 252 How Windows Systems Work 253 Windows and Segment Registers 253 Descriptors 254 Summary 256 Object-Oriented Programming Object-Oriented Programming 259 About Object-Oriented Programming 260 Misconceptions 261 The OOP Controversy 261 How It Works 262 How It All Began 263 From COBOL to Simula 263 The Debut of C Benefits of C Code Reuse 265 Zen and the Art of C++ Programming 267 A Wall Street Simulation 268 A Factory Simulation 269 Problems in Project Planning 272 The C++ Lexicon 273 Features of C Data Encapsulation and Data Abstraction 278 Inheritance 278 Multiple Inheritance 279 Polymorphism 281 Elements of a C++ Program 284 Classes and Objects 284 Member Variables 285 Member Functions 285 Summary 286

9 Visual C++ Object-Oriented Programming 11 Classes 287 Enhancing the struct 288 The C++-Style struct 289 Storing a Function in a struct 289 Limiting Access to Data in a struct 290 From struct to class 291 Instantiating an Object 292 Object Instantiation Illustrated 293 Accessing Members of a Class 293 Member Functions 293 The Scope Resolution Operator 295 Access Specifiers 295 Classes and Objects 297 Class Diagrams 304 Data Abstraction in the Zalthar Program 306 Abstract Classes 307 Subclassing 309 Virtual Functions 310 Another Example Program 315 Class Libraries 318 Summary Objects 321 From struct to Object 322 Shortcomings of C-Style Structures 325 Defining an Object's Contents 326 Using Objects 326 How Objects Are Created 326 Two Ways to Initialize Objects 327 Constructors 327 Destructors 334 Member Variables 335 Pointers to Member Variables 335 Arrays of Member Variables 338 Constant Member Variables 341 Static Member Variables 342 Static Member Functions 352 Allocating Memory for Objects 353 Allocating Memory Dynamically 354 Frame Allocation 355 Heap Allocation 356

10 Accessing Members of Objects 358 Using the (::) Operator in a Function Header 361 Access Specifiers 366 Encapsulation 366 Using Access Specifiers 368 Interpreting Access Specifiers 369 The public Access Specifier 370 The private Access Specifier 370 The protected Access Specifier 372 Publicly and Privately Derived Objects 372 Public Derivation 373 Private Derivation 373 Creating Multiple Objects of a Class 374 Creating Arrays of Objects 374 Creating Arrays of Pointers to Objects 379 Techniques for Designing Classes 381 Nested Classes 381 Composed Classes 383 Local Classes 385 friend Classes 386 Incomplete Class Declarations 386 Empty Classes 387 Scope and Linkage of Objects 388 Objects with External Linkage 388 Objects with Static Duration 388 The this Pointer 389 Summary 392 Member Functions 393 Capabilities of Member Functions 394 Kinds of Member Functions 394 Accessing Member Functions 396 Declaring and Defining Member Functions 397 Specifying Return Values of Member Functions 398 The const and volatile Keywords 400 Member Functions with const this Pointers 401 Member Functions with volatile this Pointers 403 Static and Non-Static Member Functions 405 Inline Member Functions 406 How Inline Member Functions Work 408 Accessing an Inline Member Function 408 Inline Member Functions and the Stack 409

11 Visual C++ Object-Oriented Programming Overloading Member Functions 410 Overriding Member Functions 411 Virtual Functions 411 Virtual Functions and Polymorphism 412 Pure Virtual Functions 412 Friends 413 The friend Keyword 414 friend Classes and friend Functions 416 Bridging friend Classes 418 Alternatives to Using Bridge Functions 420 Static Member Functions 422 The static Keyword 430 Initializing a Static Member Variable 430 Using Static Member Functions 431 Pointers to Member Functions 432 Using Pointers to Ordinary Functions 433 Using Pointers to Member Functions 434 Arrays of Pointers to Member Functions 436 Pointers to Static Member Functions 438 Summary Constructors and Destructors 441 Creating Constructors 442 Two Kinds of Constructors 444 Creating Objects Without Constructors 444 Destructors 445 Using Destructors Safely 445 How Destructors Are Invoked 446 Using Destructors 446 Order of Destruction 447 Destructors in the Zalthar Program 448 How Constructors Work 449 Kinds of Constructors 450 Invoking a Constructor 452 Other Ways to Invoke Constructors 453 Ground Rules for Using Constructors 454 Benefits of Using Constructors 455 Constructors Can Help Manage Memory 456 Constructors Can Initialize and Check Values 456 Conversion Constructors and Copy Constructors 458 Initializing Variables with Constructors 459

12 Contents j«yj Щ V Default Constructors 462 Calling a Default Constructor 463 When Default Constructors Are Invoked 464 Constructor Overloading 464 Using Constructors 466 Classes with Multiple Constructors 471 Order of Construction 473 Construction by the Numbers 474 Invoking Constructors in the Warrior Program 474 Constructing a const Object 475 Summary Function Overloading 479 How Function Overloading Works 480 Ground Rules for Function Overloading 481 Argument Matching 484 How Argument Matching Works 487 Argument Matching, Step by Step 488 Function Overloading and Scope 492 Overloading Constructors 493 Overloading Functions in Derived Classes 494 The Scope Resolution Operator 496 Overloading Virtual Functions 496 Overloading Static Member Functions,498 Conversion Functions 499 Summary Operator Overloading 503 How Operator Overloading Works 504 An Illustration of Operator Overloading 504 Using Operator Overloading in Math Operations 505 Writing Operator-Overloading Functions 506 The Scope of Operator-Overloading Functions 506 The Format of an Operator-Overloading Function 507 Overloading Binary and Unary Operators 508 Operators That Can Be Overloaded 509 Operator Overloading: Tips and Techniques 510 Operators that Can't Be Overloaded 511 How C++ Implements Operator Overloading 513 Rules of Operator Overloading 514 xix

13 Visual C++ Object-Oriented Programming Member Functions That Overload Operators 515 Overloading the ++ and Operators 516 Overloading the Binary + and - Operators 520 Overloading the += Operator 523 Overloading the = Operator 526 Overloading Relational Operators 547 Overloading the [] Operator 550 Overloading the () Operator 554 Overloading the & Operator 557 Overloading the -> Operator 558 Overloading Data Types 564 Overloading new and delete 565 Rules for Overloading new and delete 569 Nonmember Overloading Functions 570 Writing a Nonmember Operator-Overloading Function 571 An Operator-Overloading friend Function 573 Another Operator-Overloading friend Function 576 Summary Conversion Functions 581 How Conversion Functions Work 582 Casting 583 The Trouble with Casting 583 Function-Style Casts 584 Uses for Function-Style Casts 585 Rules for Using Function-Style Casts 585 Converting User-Defined Data Types 586 Conversion Constructor Functions 587 Defining a Class for a Conversion Function 589 Defining a Conversion Constructor 590 Converting a Variable to a Multi-Element Class 591 A More Advanced Conversion Constructor 593 Converting a Variable to a Multi-Element Class 595 Functions in the TIME.H Library 595 Conversion Constructors Step by Step 597 Member Conversion Functions 598 Writing a Member Conversion Function 600 How Member Conversion Functions Work 600 Using Member Conversion Functions 602 Illustrating Member Conversion Functions 604 Data Types Used in 1705.CPP 606 Summary 606

14 Contents 18 Copying Objects 607 Copy Constructors and operator= Functions 608 Writing an operator= Function 609 Invoking a Copy Constructor 609 Destruction Problems Illustrated 610 Writing a Copy Constructor 614 How the operator= Function Works 617 Copying Strings 621 The strcpyo Function 621 How the Program Works 626 Allocating Memory for Strings 627 Memory-Allocation Alternatives 627 Adding a String Class to the Zalthar Program 628 How the New Zalthar Program Works 634 String Classes 635 How the String Class Works 636 Using the String Class 636 Initializing a String Object with a Copy Constructor 636 Assignment Operator Overloading 637 Using Overloaded Assignment Operators 637 Summary Inheritance and Polymorphism 639 Derived Classes 640 Reasons for Using Derived Classes 640 Benefits of Using Derived Classes 641 The New Zalthar Hierarchy 649 Inheritance Rules for Constructors and Destructors 650 Accessing Objects Through Pointers 653 Virtual Functions 654 Calling Virtual Functions 654 Pure Virtual Functions 655 Overriding Virtual Functions 659 The Scope Resolution Operator 661 How Virtual Functions Work 661 Virtual Functions: Pros and Cons 664 Multiple Inheritance 664 Multiple Inheritance Illustrated 665 Multiple Inheritance in the Animal Kingdom 666 Virtual Base Classes 668 Function-Name Ambiguities in the Inheritance Chain 670 Summary 673

15 Visual C++ Object-Oriented Programming 20 Streams 675 How the iostream Classes Work 677 The iostream Library 679 Stream-Related Header Files 679 The Microsoft iostream Class Library 680 The iostream Hierarchy 680 The ios Class and Its Subclasses 681 Using Streams 688 Mixing Data Types in Streams 689 Formatting Output 690 Setting Output Width 696 The setw Manipulator 698 Setting the Padding Character 699 Alternatives to ein» and cout «700 Alternatives to the ein» Operator 700 Alternatives to cout «704 Overloading «and» 706 Overloading the «Operator 706 Overloading the» Operator 707 File I/O 708 Opening, Using, and Closing a Stream File 709 File Streams 709 The ofstream and ifstream Classes 710 The fstream Class 711 Summary 716 Part III The MFC Library 21 The Microsoft Foundation Classes 721 General Purpose Classes 723 The CObject Class 725 Benefits of Using the CObject Class 725 Serialization 727 The DYNCREATE Macros 734 The DYNAMIC Macros 735 Diagnostic Aids 737 Exception Handling 741 Other MFC Classes 743 File Classes 743 Collection Classes 745 The CString Class 747 Time-Related Classes 748

16 Contents The Example Program 748 Architecture of the Example Program 750 Compiling the Example Program 752 Running the Example Program 753 Summary The Visual Workbench 779 Visual Workbench Components 780 Message-Driven Programs 781 C++ Program Architecture 782 The WinMainQ Function 783 Documents and Views 783 The Visual Workbench Tools 787 AppWizard 787 App Studio 795 How the Character-Creation Dialog Box Works 803 Using Class Wizard 805 The Class Wizard Window 805 How ClassWizard Works 806 Command Binding 808 Creating Dialog Boxes 809 The Example Program 813 Summary Windows and Views 865 How Documents and Views Work 867 Features of the CDocument Class 869 Features of the CView Class 869 Using Documents 870 How Windows Work in Visual C Windows Classes 871 The CWnd Class 871 The Big 5 Windows Classes 873 Dialog Boxes 884 The CDialog Class 884 How Dialog Boxes Work 885 Retrieving Data the Old Way 890 Summary Visual C++ Graphics 893 The CDC Class 894 CDC Subclasses 895 t

17 Visual C++ Object-Oriented Programming The CGdiObject Class 896 Using the CDC and CGdiObject Classes 896 What's in a Name 897 Creating Graphics in Visual C Visual C++ Graphics, Step by Step 899 TheOnPaintQ and OnDraw() Functions 900 TheOnDrawQ Function, Step by Step 902 Drawing Text with CDC and GDI Objects 903 Creating and Deleting Graphics Objects 904 One-Step Creation of a Graphics Object 904 Two-Step Creation of a Graphics Object 904 Using Bitmaps in Visual C Creating a Bitmap Object 906 Drawing Irregular Shapes 909 Drawing the Zalthar Players 911 Animation 914 Zalthar: The Final Episode 916 Summary 969 Appendix A ASCII Chart 971 Appendix В The 80X86 Chip Family 975 The 8086 and 8088 Processors 976 The 8086, the 8088, and Real Mode 976 How Segment:Offset Addressing Works 977 Segment Registers and Offset Registers 977 SegmentOffset Addressing: A More Complex Example 980 Ambiguities in SegmentOffset Addressing 981 The Microprocessor 983 Protected Mode and SegmentOffset Addressing 983 The 386 Processor Protected Mode 985 Virtual-8086 Mode 986 The 486 Processor 986 Using Pointers in C++ Programs 986 Bibliography 989 Index 993