- •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
C++ Interviews
More challenging inheritance questions have to do with the relationship between a superclass and a subclass. Be sure you know how the different access levels work, and the difference between private and protected. Remind yourself of the phenomenon known as slicing, when certain types of casts cause a class to lose its subclass information.
Chapter 11: Writing Generic Code with Templates
As one of the most arcane parts of C++, templates are a good way for interviewers to separate the C++ novices from the pros. While most interviewers will forgive you for not remembering some of the advanced template syntax, you should go into the interview knowing the basics.
Things to Remember
How to write a basic templatized class
The two main disadvantages of templates — ugly syntax and code bloat
How to use a templatized class
Types of Questions
Many interview questions start out with a simple problem and gradually add complexity. Often, interviewers have an endless amount of complexity that they are prepared to add and they simply want to see how far you get. For example, an interviewer might begin a problem by asking you to create a class that provides sequential access to a fixed number of ints. Next, the class will need to grow to accommodate an arbitrary sized array. Then, it will need arbitrary data types, which is where templates come in. From there, the interviewer could take the problem in a number of directions, asking you to use operator overloading to provide array-like syntax or continuing down the template path by asking you to provide a default type.
Templates are more likely to be employed in the solution of another coding problem than to be asked about explicitly. You should brush up on the basics in case the subject comes up. However, most interviewers understand that the template syntax is difficult, and asking someone to write complex template code in an interview is rather cruel.
Chapter 12: Understanding C++ Quirks
and Oddities
Many interviews tend to focus on the more obscure cases because that way experienced C++ programmers can demonstrate that they have conquered the unusual parts of C++. Sometimes interviewers have difficulty coming up with interesting questions and end up asking the most obscure question they can think of.
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Appendix A
Things to Remember
References must be bound to a variable when they are declared and the binding cannot be changed.
The advantages of pass-by-reference over pass-by-value
The many uses of const
The many uses of static
The different types of casts in C++
Types of Questions
Asking a candidate to define const and static is a classic C++ interview question. Both keywords provide a sliding scale with which an interviewer can assess an answer. For example, a fair candidate will talk about static methods and static data members. A good candidate will give good examples of static methods and static data members. A great candidate will also know about static linkage and static variables in functions.
The edge cases described in this chapter also come in find-the-bug type problems. Be on the lookout for misuse of references. For example, imagine a class that contains a reference as a data member:
class Gwenyth
{
public:
int& mCaversham;
};
Because mCaversham is a reference, it needs to be bound to a variable when the class is constructed. To do that, you’ll need to use an initializer list. The class could take the variable to be referenced as a parameter to the constructor:
class Gwenyth
{
public: Gwenyth(int i);
int& mCaversham;
};
Gwenyth::Gwenyth(int i) : mCaversham(i)
{
}
Chapter 13: Effective Memor y Management
Memory-related questions tend to be asked by low-level programmers or C++ programmers who have a background in C. The goal is to determine whether the object-oriented aspects of C++ have distanced you too much from the underlying implementation details. Memory management questions will give you a chance to prove that you know what’s really going on.
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C++ Interviews
Things to Remember
Drawing the stack and the heap can help you understand what’s going on.
Use new and delete instead of malloc() and free().
Use new[] and delete[] for arrays.
If you have an array of pointers to objects, you still need to allocate memory for each individual pointer and delete the memory — the array allocation syntax doesn’t take care of pointers!
In a pinch, you can always say, “Of course in real life, I would run this through valgrind to expose the problem.”
Types of Questions
Find-the-bug questions often contain memory issues, such as double-deletion, new/new[] mixup, and memory leaks. When you are tracing through code that makes heavy use of pointers and arrays, you should draw and update the state of memory as you process each line of code. Even if you see the answer right away, it will let the interviewer know that you’re able to draw the state of memory.
Another good way to find out if a candidate understands memory is to ask how pointers and arrays differ. At this point, the differences may be so tacit in your mind that the question catches you off-guard for a moment. If that’s the case, skim Chapter 13 again for the discussion.
Chapter 14: Demystifying C++ I/O
If you’re interviewing for a job writing GUI applications, you probably won’t get too many questions about I/O streams because GUI apps tend to use other mechanisms for I/O. However, streams can come up in other problems and, as a standard part of C++, they are fair game as far as the interviewer is concerned.
Things to Remember
The definition of a stream
Basic input and output using streams
The concept of manipulators
Types of streams (console, file, string, etc.)
Error-handling techniques
The importance of internationalization
Types of Questions
I/O may come up in the context of any question. For example, the interviewer could ask you to read in a file containing test scores and put them in a vector. This question tests basic C++ skills, basic STL, and basic I/O. Even if I/O is only a small part of the problem you’re working on, be sure to check for errors.
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Appendix A
If you don’t, you’re giving the interviewer an opportunity to say something negative about your otherwise perfect program.
Your interviewer may not ask specifically about internationalization, but you can show your worldwide appeal by using wchar_t instead of char during the interview. If you do receive a question about your experience with internationalization, be sure to mention the importance of considering worldwide use from the beginning and show that you know about the locale facilities of C++.
Chapter 15: Handling Errors
Managers sometimes shy away from hiring recent graduates or novice programmers for vital (and highpaying) jobs because it is assumed that they don’t write production-quality code. You can prove to an interviewer that your code won’t keel over randomly by demonstrating your error-handling skills during an interview.
Things to Remember
Catch exceptions as const references.
For production code, hierarchies of exceptions are preferable to a few generic ones.
Throw lists in C++ aren’t like throw lists in Java!
Smart pointers help avoid memory leaks when exceptions are thrown.
Types of Questions
You’re unlikely to get a question directly about exceptions, unless it’s something cruelly specific, such as asking you to describe how the stack unwinds. However, interviewers will be on the lookout to see how you report and handle errors.
Of course, not all programmers understand or appreciate exceptions. Some may even have a bias against them for performance reasons. If the interviewer asks you to do something without exceptions, you’ll have to revert to traditional NULL checks and error codes. That would be a good time to demonstrate your knowledge of nothrow new!
Chapter 16: Overloading C++ Operators
It’s possible, though somewhat unlikely, that you would have to perform something more difficult than a simple operator overload during an interview. Some interviewers like to have an advanced question on hand that they don’t really expect anybody to answer correctly. The intricacies of operator overloading make great nearly impossible questions because few programmers get the syntax right without looking it up. That means it’s a great area to review before an interview.
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