- •Contents
- •Introduction
- •Who This Book Is For
- •What This Book Covers
- •How This Book Is Structured
- •What You Need to Use This Book
- •Conventions
- •Source Code
- •Errata
- •p2p.wrox.com
- •The Basics of C++
- •The Obligatory Hello, World
- •Namespaces
- •Variables
- •Operators
- •Types
- •Conditionals
- •Loops
- •Arrays
- •Functions
- •Those Are the Basics
- •Diving Deeper into C++
- •Pointers and Dynamic Memory
- •Strings in C++
- •References
- •Exceptions
- •The Many Uses of const
- •C++ as an Object-Oriented Language
- •Declaring a Class
- •Your First Useful C++ Program
- •An Employee Records System
- •The Employee Class
- •The Database Class
- •The User Interface
- •Evaluating the Program
- •What Is Programming Design?
- •The Importance of Programming Design
- •Two Rules for C++ Design
- •Abstraction
- •Reuse
- •Designing a Chess Program
- •Requirements
- •Design Steps
- •An Object-Oriented View of the World
- •Am I Thinking Procedurally?
- •The Object-Oriented Philosophy
- •Living in a World of Objects
- •Object Relationships
- •Abstraction
- •Reusing Code
- •A Note on Terminology
- •Deciding Whether or Not to Reuse Code
- •Strategies for Reusing Code
- •Bundling Third-Party Applications
- •Open-Source Libraries
- •The C++ Standard Library
- •Designing with Patterns and Techniques
- •Design Techniques
- •Design Patterns
- •The Reuse Philosophy
- •How to Design Reusable Code
- •Use Abstraction
- •Structure Your Code for Optimal Reuse
- •Design Usable Interfaces
- •Reconciling Generality and Ease of Use
- •The Need for Process
- •Software Life-Cycle Models
- •The Stagewise and Waterfall Models
- •The Spiral Method
- •The Rational Unified Process
- •Software-Engineering Methodologies
- •Extreme Programming (XP)
- •Software Triage
- •Be Open to New Ideas
- •Bring New Ideas to the Table
- •Thinking Ahead
- •Keeping It Clear
- •Elements of Good Style
- •Documenting Your Code
- •Reasons to Write Comments
- •Commenting Styles
- •Comments in This Book
- •Decomposition
- •Decomposition through Refactoring
- •Decomposition by Design
- •Decomposition in This Book
- •Naming
- •Choosing a Good Name
- •Naming Conventions
- •Using Language Features with Style
- •Use Constants
- •Take Advantage of const Variables
- •Use References Instead of Pointers
- •Use Custom Exceptions
- •Formatting
- •The Curly Brace Alignment Debate
- •Coming to Blows over Spaces and Parentheses
- •Spaces and Tabs
- •Stylistic Challenges
- •Introducing the Spreadsheet Example
- •Writing Classes
- •Class Definitions
- •Defining Methods
- •Using Objects
- •Object Life Cycles
- •Object Creation
- •Object Destruction
- •Assigning to Objects
- •Distinguishing Copying from Assignment
- •The Spreadsheet Class
- •Freeing Memory with Destructors
- •Handling Copying and Assignment
- •Different Kinds of Data Members
- •Static Data Members
- •Const Data Members
- •Reference Data Members
- •Const Reference Data Members
- •More about Methods
- •Static Methods
- •Const Methods
- •Method Overloading
- •Default Parameters
- •Inline Methods
- •Nested Classes
- •Friends
- •Operator Overloading
- •Implementing Addition
- •Overloading Arithmetic Operators
- •Overloading Comparison Operators
- •Building Types with Operator Overloading
- •Pointers to Methods and Members
- •Building Abstract Classes
- •Using Interface and Implementation Classes
- •Building Classes with Inheritance
- •Extending Classes
- •Overriding Methods
- •Inheritance for Reuse
- •The WeatherPrediction Class
- •Adding Functionality in a Subclass
- •Replacing Functionality in a Subclass
- •Respect Your Parents
- •Parent Constructors
- •Parent Destructors
- •Referring to Parent Data
- •Casting Up and Down
- •Inheritance for Polymorphism
- •Return of the Spreadsheet
- •Designing the Polymorphic Spreadsheet Cell
- •The Spreadsheet Cell Base Class
- •The Individual Subclasses
- •Leveraging Polymorphism
- •Future Considerations
- •Multiple Inheritance
- •Inheriting from Multiple Classes
- •Naming Collisions and Ambiguous Base Classes
- •Interesting and Obscure Inheritance Issues
- •Special Cases in Overriding Methods
- •Copy Constructors and the Equals Operator
- •The Truth about Virtual
- •Runtime Type Facilities
- •Non-Public Inheritance
- •Virtual Base Classes
- •Class Templates
- •Writing a Class Template
- •How the Compiler Processes Templates
- •Distributing Template Code between Files
- •Template Parameters
- •Method Templates
- •Template Class Specialization
- •Subclassing Template Classes
- •Inheritance versus Specialization
- •Function Templates
- •Function Template Specialization
- •Function Template Overloading
- •Friend Function Templates of Class Templates
- •Advanced Templates
- •More about Template Parameters
- •Template Class Partial Specialization
- •Emulating Function Partial Specialization with Overloading
- •Template Recursion
- •References
- •Reference Variables
- •Reference Data Members
- •Reference Parameters
- •Reference Return Values
- •Deciding between References and Pointers
- •Keyword Confusion
- •The const Keyword
- •The static Keyword
- •Order of Initialization of Nonlocal Variables
- •Types and Casts
- •typedefs
- •Casts
- •Scope Resolution
- •Header Files
- •C Utilities
- •Variable-Length Argument Lists
- •Preprocessor Macros
- •How to Picture Memory
- •Allocation and Deallocation
- •Arrays
- •Working with Pointers
- •Array-Pointer Duality
- •Arrays Are Pointers!
- •Not All Pointers Are Arrays!
- •Dynamic Strings
- •C-Style Strings
- •String Literals
- •The C++ string Class
- •Pointer Arithmetic
- •Custom Memory Management
- •Garbage Collection
- •Object Pools
- •Function Pointers
- •Underallocating Strings
- •Memory Leaks
- •Double-Deleting and Invalid Pointers
- •Accessing Out-of-Bounds Memory
- •Using Streams
- •What Is a Stream, Anyway?
- •Stream Sources and Destinations
- •Output with Streams
- •Input with Streams
- •Input and Output with Objects
- •String Streams
- •File Streams
- •Jumping around with seek() and tell()
- •Linking Streams Together
- •Bidirectional I/O
- •Internationalization
- •Wide Characters
- •Non-Western Character Sets
- •Locales and Facets
- •Errors and Exceptions
- •What Are Exceptions, Anyway?
- •Why Exceptions in C++ Are a Good Thing
- •Why Exceptions in C++ Are a Bad Thing
- •Our Recommendation
- •Exception Mechanics
- •Throwing and Catching Exceptions
- •Exception Types
- •Throwing and Catching Multiple Exceptions
- •Uncaught Exceptions
- •Throw Lists
- •Exceptions and Polymorphism
- •The Standard Exception Hierarchy
- •Catching Exceptions in a Class Hierarchy
- •Writing Your Own Exception Classes
- •Stack Unwinding and Cleanup
- •Catch, Cleanup, and Rethrow
- •Use Smart Pointers
- •Common Error-Handling Issues
- •Memory Allocation Errors
- •Errors in Constructors
- •Errors in Destructors
- •Putting It All Together
- •Why Overload Operators?
- •Limitations to Operator Overloading
- •Choices in Operator Overloading
- •Summary of Overloadable Operators
- •Overloading the Arithmetic Operators
- •Overloading Unary Minus and Unary Plus
- •Overloading Increment and Decrement
- •Overloading the Subscripting Operator
- •Providing Read-Only Access with operator[]
- •Non-Integral Array Indices
- •Overloading the Function Call Operator
- •Overloading the Dereferencing Operators
- •Implementing operator*
- •Implementing operator->
- •What in the World Is operator->* ?
- •Writing Conversion Operators
- •Ambiguity Problems with Conversion Operators
- •Conversions for Boolean Expressions
- •How new and delete Really Work
- •Overloading operator new and operator delete
- •Overloading operator new and operator delete with Extra Parameters
- •Two Approaches to Efficiency
- •Two Kinds of Programs
- •Is C++ an Inefficient Language?
- •Language-Level Efficiency
- •Handle Objects Efficiently
- •Use Inline Methods and Functions
- •Design-Level Efficiency
- •Cache as Much as Possible
- •Use Object Pools
- •Use Thread Pools
- •Profiling
- •Profiling Example with gprof
- •Cross-Platform Development
- •Architecture Issues
- •Implementation Issues
- •Platform-Specific Features
- •Cross-Language Development
- •Mixing C and C++
- •Shifting Paradigms
- •Linking with C Code
- •Mixing Java and C++ with JNI
- •Mixing C++ with Perl and Shell Scripts
- •Mixing C++ with Assembly Code
- •Quality Control
- •Whose Responsibility Is Testing?
- •The Life Cycle of a Bug
- •Bug-Tracking Tools
- •Unit Testing
- •Approaches to Unit Testing
- •The Unit Testing Process
- •Unit Testing in Action
- •Higher-Level Testing
- •Integration Tests
- •System Tests
- •Regression Tests
- •Tips for Successful Testing
- •The Fundamental Law of Debugging
- •Bug Taxonomies
- •Avoiding Bugs
- •Planning for Bugs
- •Error Logging
- •Debug Traces
- •Asserts
- •Debugging Techniques
- •Reproducing Bugs
- •Debugging Reproducible Bugs
- •Debugging Nonreproducible Bugs
- •Debugging Memory Problems
- •Debugging Multithreaded Programs
- •Debugging Example: Article Citations
- •Lessons from the ArticleCitations Example
- •Requirements on Elements
- •Exceptions and Error Checking
- •Iterators
- •Sequential Containers
- •Vector
- •The vector<bool> Specialization
- •deque
- •list
- •Container Adapters
- •queue
- •priority_queue
- •stack
- •Associative Containers
- •The pair Utility Class
- •multimap
- •multiset
- •Other Containers
- •Arrays as STL Containers
- •Strings as STL Containers
- •Streams as STL Containers
- •bitset
- •The find() and find_if() Algorithms
- •The accumulate() Algorithms
- •Function Objects
- •Arithmetic Function Objects
- •Comparison Function Objects
- •Logical Function Objects
- •Function Object Adapters
- •Writing Your Own Function Objects
- •Algorithm Details
- •Utility Algorithms
- •Nonmodifying Algorithms
- •Modifying Algorithms
- •Sorting Algorithms
- •Set Algorithms
- •The Voter Registration Audit Problem Statement
- •The auditVoterRolls() Function
- •The getDuplicates() Function
- •The RemoveNames Functor
- •The NameInList Functor
- •Testing the auditVoterRolls() Function
- •Allocators
- •Iterator Adapters
- •Reverse Iterators
- •Stream Iterators
- •Insert Iterators
- •Extending the STL
- •Why Extend the STL?
- •Writing an STL Algorithm
- •Writing an STL Container
- •The Appeal of Distributed Computing
- •Distribution for Scalability
- •Distribution for Reliability
- •Distribution for Centrality
- •Distributed Content
- •Distributed versus Networked
- •Distributed Objects
- •Serialization and Marshalling
- •Remote Procedure Calls
- •CORBA
- •Interface Definition Language
- •Implementing the Class
- •Using the Objects
- •A Crash Course in XML
- •XML as a Distributed Object Technology
- •Generating and Parsing XML in C++
- •XML Validation
- •Building a Distributed Object with XML
- •SOAP (Simple Object Access Protocol)
- •. . . Write a Class
- •. . . Subclass an Existing Class
- •. . . Throw and Catch Exceptions
- •. . . Read from a File
- •. . . Write to a File
- •. . . Write a Template Class
- •There Must Be a Better Way
- •Smart Pointers with Reference Counting
- •Double Dispatch
- •Mix-In Classes
- •Object-Oriented Frameworks
- •Working with Frameworks
- •The Model-View-Controller Paradigm
- •The Singleton Pattern
- •Example: A Logging Mechanism
- •Implementation of a Singleton
- •Using a Singleton
- •Example: A Car Factory Simulation
- •Implementation of a Factory
- •Using a Factory
- •Other Uses of Factories
- •The Proxy Pattern
- •Example: Hiding Network Connectivity Issues
- •Implementation of a Proxy
- •Using a Proxy
- •The Adapter Pattern
- •Example: Adapting an XML Library
- •Implementation of an Adapter
- •Using an Adapter
- •The Decorator Pattern
- •Example: Defining Styles in Web Pages
- •Implementation of a Decorator
- •Using a Decorator
- •The Chain of Responsibility Pattern
- •Example: Event Handling
- •Implementation of a Chain of Responsibility
- •Using a Chain of Responsibility
- •Example: Event Handling
- •Implementation of an Observer
- •Using an Observer
- •Chapter 1: A Crash Course in C++
- •Chapter 3: Designing with Objects
- •Chapter 4: Designing with Libraries and Patterns
- •Chapter 5: Designing for Reuse
- •Chapter 7: Coding with Style
- •Chapters 8 and 9: Classes and Objects
- •Chapter 11: Writing Generic Code with Templates
- •Chapter 14: Demystifying C++ I/O
- •Chapter 15: Handling Errors
- •Chapter 16: Overloading C++ Operators
- •Chapter 17: Writing Efficient C++
- •Chapter 19: Becoming Adept at Testing
- •Chapter 20: Conquering Debugging
- •Chapter 24: Exploring Distributed Objects
- •Chapter 26: Applying Design Patterns
- •Beginning C++
- •General C++
- •I/O Streams
- •The C++ Standard Library
- •C++ Templates
- •Integrating C++ and Other Languages
- •Algorithms and Data Structures
- •Open-Source Software
- •Software-Engineering Methodology
- •Programming Style
- •Computer Architecture
- •Efficiency
- •Testing
- •Debugging
- •Distributed Objects
- •CORBA
- •XML and SOAP
- •Design Patterns
- •Index
Chapter 1
Operator |
Description |
Usage |
!= |
Not equals. The result of |
if (i != 3) { |
|
the statement is true if the |
std::cout << “i is not 3”; |
|
left-hand side does not |
} |
|
equal the right-hand side. |
|
! |
Logical not. Negates the |
if (!someBoolean) { |
|
true/false status of a |
std::cout << “someBoolean is false”; |
|
Boolean expression. |
} |
|
This is a unary operator. |
|
&&Logical and. The result is true if both parts of the expression are true.
||Logical or. The result is true if either part of the expression is true.
if (someBoolean && someOtherBoolean) { std::cout << “both are true”;
}
if (someBoolean || someOtherBoolean) { std::cout << “at least one is true”;
}
C++ uses short-circuit logic when evaluating an expression. That means that once the final result is certain, the rest of the expression won’t be evaluated. For example, if you are doing a logical or of several Boolean expressions as shown below, the result is known to be true as soon as one of them is found to be true. The rest won’t even be checked.
bool result = bool1 || bool2 || (i > 7) || (27 / 13 % i + 1) < 2;
In the example above, if bool1 is found to be true, the entire expression must be true, so the other parts aren’t evaluated. In this way, the language saves your code from doing unnecessary work. It can, however, be a source of hard-to-find bugs if the later expressions in some way influence the state of the program (for example, by calling a separate function). The following code shows a statement using && that will short-circuit after the second term because 1 always evaluates to true.
bool result = bool1 && 1 && (i > 7) && !done;
Loops
Computers are great for doing the same thing over and over. C++ provides three types of looping structures.
The While Loop
while loops let you perform a block of code repeatedly as long as an expression evaluates to true. For example, the following completely silly code will output “This is silly.” five times.
int i = 0; while (i < 5) {
std::cout << “This is silly.” << std::endl; i++;
}
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A Crash Course in C++
The keyword break can be used within a loop to immediately get out of the loop and continue execution of the program. The keyword continue can be used to return to the top of the loop and reevaluate the while expression. Both are often considered poor style because they cause the execution of a program to jump around somewhat haphazardly.
The Do/While Loop
C++ also has a variation on the while loop called do/while. It works similarly to the while loop, except that the code to be executed comes first, and the conditional check for whether or not to continue happens at the end. In this way, you can use a loop when you want a block of code to always be executed at least once and possibly additional times based on some condition. The example that follows will output “This is silly.” once even though the condition will end up being false.
int i = 100; do {
std::cout << “This is silly.” << std::endl; i++;
} while (i < 5);
The For Loop
The for loop provides another syntax for looping. Any for loop can be converted to a while loop and vice versa. However, the for loop syntax is often more convenient because it looks at a loop in terms of a starting expression, an ending condition, and a statement to execute at the end of every iteration. In the following code, i is initialized to 0, the loop will continue as long as i is less than 5, and at the end of every iteration, i is incremented by 1. This code does the same thing as the while loop example, but to some programmers, it is easier to read because the starting value, ending condition, and per-iteration statement are all visible on one line.
for (int i = 0; i < 5; i++) {
std::cout << “This is silly.” << std::endl;
}
Arrays
Arrays hold a series of values, all of the same type, each of which can be accessed by its position in the array. In C++, you must provide the size of the array when the array is declared. You cannot give a variable as the size — it must be a constant value. The code that follows shows the declaration of an array of 10 integers followed by a for loop that initializes each integer to zero.
int myArray[10];
for (int i = 0; i < 10; i++) { myArray[i] = 0;
}
15
Chapter 1
The preceding example shows a one-dimensional array, which you can think of as a line of integers, each with its own numbered compartment. C++ allows multidimensional arrays. You might think of a twodimensional array as a checkerboard, where each location has a position along the x-axis and a position along the y-axis. Three-dimensional and higher arrays are harder to picture and are rarely used. The code below shows the syntax for allocating a two-dimensional array of characters for a Tic-Tac-Toe board and then putting an “o” in the center square.
char ticTacToeBoard[3][3];
ticTacToeBoard[1][1] = ‘o’;
Figure 1-1 shows a visual representation of this board with the position of each square.
ticTacToeBoard[0][0] ticTacToeBoard[0][1] |
ticTacToeBoard[0][2] |
ticTacToeBoard[1][0] ticTacToeBoard[1][1] |
ticTacToeBoard[1][2] |
ticTacToeBoard[2][0] ticTacToeBoard[2][1] |
ticTacToeBoard[2][2] |
Figure 1-1
In C++, the first element of an array is always at position 0, not position 1! The last position of the array is always the size of the array minus 1!
Functions
For programs of any significant size, placing all the code inside of main() is unmanageable. To make programs easy to understand, you need to break up, or decompose, code into concise functions.
In C++, you first declare a function to make it available for other code to use. If the function is used inside a particular file of code, you generally declare and define the function in the source file. If the function is for use by other modules or files, you generally put the declaration in a header file and the definition in a source file.
16
A Crash Course in C++
Function declarations are often called “function prototypes” or “signatures” to emphasize that they represent how the function can be accessed, but not the code behind it.
A function declaration is shown below. This example has a return type of void, indicating that the function does not provide a result to the caller. The caller must provide two arguments for the function to work with — an integer and a character.
void myFunction(int i, char c);
Without an actual definition to match this function declaration, the link stage of the compilation process will fail because code that makes use of the function myFunction() will be calling nonexistent code. The following definition simply prints the values of the two parameters.
void myFunction(int i, char c)
{
std::cout << “the value of i is “ << i << std::endl; std::cout << “the value of c is “ << c << std::endl;
}
Elsewhere in the program, you can make calls to myFunction() and pass in constants or variables for the two parameters. Some sample function calls are shown here:
myFunction(8, ‘a’); myFunction(someInt, ‘b’); myFunction(5, someChar);
In C++, unlike C, a function that takes no parameters just has an empty parameter list. It is not necessary to use “void” to indicate that no parameters are taken. However, you should still use “void” to indicate when no value is returned.
C++ functions can also return a value to the caller. The following function declaration and definition is for a function that adds two numbers and returns the result.
int addNumbers(int number1, int number2);
int addNumbers(int number1, int number2)
{
int result = number1 + number2; return (result);
}
Those Are the Basics
At this point, you have reviewed the basic essentials of C++ programming. If this section was a breeze, skim the next section to make sure that you’re up to speed on the more advanced material. If you
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