ch01.htm

c++语言操作手册

<p>C++ differs from other object-oriented languages in many ways. For instance, 
  C++ is not a root-based language, nor does it operate on a runtime virtual machine. 
  These differences significantly broaden the domains in which C++ can be used.</p>
<h3> <a name="Heading11"> Backward Compatibility with Legacy Systems</a></h3>
<p>The fact that legacy C code can be combined seamlessly with new C++ code is 
  a major advantage. Migration from C to C++ does not force you to throw away 
  good, functional C code. Many commercial frameworks, and even some components 
  of the Standard Library itself, are built upon legacy C code that is wrapped 
  in an object-oriented interface. </p>
<h3> <a name="Heading12"> Performance</a></h3>
<p>Interpreted languages allow easier code porting, albeit at the cost of significant 
  performance overhead. C++, on the other hand, uses the compile and link model 
  it inherited from C. One of the goals of C++ designers has been to keep it as 
  efficient as possible; a compile-and-link model enables very efficient code 
  generation and optimization. Another performance factor is the use of a garbage 
  collector. This feature is handy and prevents some common programming bugs; 
  however, garbage collected languages are disqualifies for time-critical application 
  development, where determinacy is paramount. For that reason, C++ does not have 
  a garbage collector.</p>
<h3> <a name="Heading13"> Object-Orientation and Other Useful Paradigms</a></h3>
<p>In addition to object-oriented programming, C++ supports other useful programming 
  styles, including procedural programming, object-based programming, and generic 
  programming -- making it a multi-paradigm, general-purpose programming language.</p>
<p></p>
<p> </p>
<h4> Procedural Programming</h4>
<p>Procedural programming is not very popular these days. However, there are some 
  good reasons for C++ to support this style of programming, even today.</p>
<p><b> Gradual Migration of C Programmers To C++</b></p>
<p>C programmers who make their first steps in C++ are not forced to throw all 
  their expertise away. Many primitives and fundamental concepts of C++ were inherited 
  from C, including built-in operators and fundamental types, pointers, the notion 
  of dynamic memory allocation, header files, preprocessor, and so on. As a transient 
  phase, C programmers can still remain productive when the shift to C++ is made.</p>
<p><b>Bilingual Environments</b></p>
<p>C++ and C code can work together. Under certain conditions, this combination 
  is synergetic and robust.</p>
<p><b>Machine-Generated Code</b></p>
<p>Many software tools and generators generate C code as an intermediate stage 
  of application build. For example, SQL queries on most relational databases 
  are translated into C code, which is in turn compiled and linked. There's not 
  much point in forcing these generators to produce C++ code (although some do 
  so) when the generated code is not going to be used by human programmers. Furthermore, 
  many early C++ compilers were not really compilers in the true meaning of the 
  word; they are better described as translators because they translated C++ code 
  into intermediate C code that was later compiled and linked. In fact, any valid 
  C++ programs can be translated directly into pure C code.</p>
<h3> <a name="Heading14">Object-Oriented Programming</a></h3>
<p>This is the most widely used style of programming in C++. The intent of this 
  book is to deliver useful guidelines and rules of thumb for efficient, reliable, 
  reusable, and easy to maintain object-oriented code. But there is no universal 
  consensus as to what OO really is; the definitions vary among schools, languages, 
  and users. There <i>is</i>, however, a consensus about a common denominator 
  -- a combination of encapsulation, information hiding, polymorphism, dynamic 
  binding, and inheritance. Some maintain that advanced object-oriented consists 
  of generic programming support and multiple inheritance. These concepts will 
  be discussed in depth in the chapters that follow.</p>
<h3> <a name="Heading15">Generic Programming</a></h3>
<p>Generic programming proceeds one step beyond object-oriented programming in 
  pursuing reusability. Two important features of C++, templates and operator 
  overloading, are the basis of generic programming. STL, a collection of generic 
  algorithms and containers, is probably the most impressive manifestation of 
  this paradigm.</p>
<h2> <a name="Heading16">Aim Of the Book</a></h2>
<p>This book is aimed at experienced C++ developers who seek a guide for enhancing 
  their design and programming proficiency. It discloses facts and techniques 
  and provides a knowledge base for advanced, Standard-compliant, and efficient 
  use of C++. In addition, the book also explains the underlying mechanism behind 
  the high-level features of the language, and it explains the philosophy behind 
  the design and evolution of C++.</p>
<h2> <a name="Heading17"> Target Audience</a></h2>
<p>The target audience is intermediate and advanced level C++ developers who want 
  to improve their proficiency by acquiring new programming techniques and design 
  idioms. On top of adding many new features to the language, the standardization 
  committee has deprecated several features and library components. In this book, 
  readers who want to develop long lasting, future-proof C++ software can find 
  a comprehensive list of deprecated features and their recommended alternatives.</p>
<h2> <a name="Heading18">Organization of the Book</a></h2>
<p><b>Chapter 2</b>, "Standard Briefing: The Latest Addenda to ANSI/ISO C++," 
  presents some of the key terms that are used in the C++ Standard, and which 
  are used extensively in this book. Following this, the recent changes and extensions 
  to C++ are described. Finally, Chapter 2 gives an overview of the deprecated 
  features that are listed in the Standard, and suggests standard-conforming replacements 
  for them.</p>
<p><b>Chapter 3</b>, "Operator Overloading," explores the benefits as well as 
  the potential problems of operator overloading. It discusses the restrictions 
  that apply to operator overloading and explains how to use conversion operators.</p>
<p><b>Chapter 4</b>, "Special Member Functions: Default Constructor, Copy Constructor, 
  Destructor, and Assignment Operator," explains the semantics of the special 
  member functions and their role in class design. It also demonstrates several 
  techniques and guidelines for an effective usage of these special member functions. 
</p>
<p><b>Chapter 5</b>, "Object-Oriented Programming and Design," provides a brief 
  survey of the various programming styles that are supported by C++, focusing 
  on the principles of object-oriented design and programming.</p>
<p><b>Chapter 6</b>, "Exception Handling," first describes traditional error handling 
  methods and their disadvantages, and then presents standard exception handling. 
  A brief historical account of the design of exception handling is provided and, 
  finally, exception handling-related performance issues are discussed.</p>
<p><b>Chapter 7</b>, "Runtime Type Information," discusses the three components 
  of runtime type information (RTTI), namely <tt>typeid</tt>, <tt>dynamic_cast</tt> 
  and class <tt>type_info</tt>. In addition, it explains when the use of RTTI 
  is necessary. Finally, it discusses the performance overhead associated with 
  runtime type information.</p>
<p><b>Chapter 8</b>, "Namespaces," elucidates the rationale behind the addition 
  of namespaces to the language and the problems that namespaces solve. Then it 
  demonstrates how namespaces are used in practice, and how they interact with 
  other language features.</p>
<p><b>Chapter 9</b>, "Templates," discusses various aspects of designing and implementing 
  templates, including class templates, function templates, and template issues 
  that are of special concern (such as pointers to members, virtual member functions 
  within a template class, inheritance relations, and explicit instantiations).</p>
<p><b>Chapter 10</b>, "STL and Generic Programming," is an introduction to the 
  Standard Template Library and to generic programming in general. It discusses 
  the principles of generic programming, focusing on STL as an exemplary framework 
  of generic programming. This chapter also demonstrates the use of STL components: 
  containers, algorithms, iterators, allocators, adapters, binders, and function 
  objects. The most widely used STL components, <tt>std::vector</tt> and <tt>std::string</tt>, 
  are explored in detail.</p>
<p><b>Chapter 11</b>, "Memory Management," explains the memory model of C++. It 
  describes the three types of data storage: static, automatic, and free store. 
  This chapter also delves into the semantics of operators <tt>new</tt> and <tt>delete 
  and their underlying implementation</tt>. In addition, it demonstrates the use 
  of advanced memory management techniques and guides you in avoiding common memory-related 
  errors.</p>
<p><b>Chapter 12</b>, "Optimizing Your Code," is dedicated to code optimization. 
  It provides useful guidelines and tips for writing more efficient code, and 
  it proceeds toward more aggressive optimization techniques for minimizing space 
  and accelerating runtime speed.</p>
<p><b>Chapter 13</b>, "C Language Compatibility Issues," demonstrates how to migrate 
  from C to C++ and, in particular, how to migrate from procedural programming 
  to object-orientation. It lists the differences between the C subset of C++ 
  and ISO C. Finally, it delves into the underlying representation of C++ objects 
  in memory and their compatibility with C structs.</p>
<p><b>Chapter 14</b>, "Concluding Remarks and Future Directions," seals this book. 
  It describes the principles and guidelines in the design and evolution of C++ 
  throughout the last two decades, and compares it to the evolution of other, 
  less successful programming languages. Then it lists features that almost made 
  it into the Standard. Next, it discusses possible future extensions, including 
  automated garbage collection, object persistence, and concurrency. Other hypothetical 
  future extensions that are described are dynamically linked libraries, rule-based 
  programming, and extensible member functions. </p>
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