C++编程语言第三版 - Bjarne Stroustrup

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"The C++ Programming Language.pdf - 一本英文版的C++编程书籍，由Bjarne Stroustrup编写，是C++编程语言的第三版，由AT&T Labs的Murray Hill, New Jersey的Addison-Wesley出版。" 《C++编程语言》是Bjarne Stroustrup所著的一本经典著作，它详细阐述了C++编程语言的各个方面。作为C++的创造者，Stroustrup在书中深入浅出地介绍了这一强大的系统级和应用级编程语言。第三版的更新内容涵盖了C++语言自第二版以来的重要发展，包括标准模板库（STL）、命名空间、异常处理、模板元编程等现代C++特性。这本书不仅适合初学者，也对有经验的C++开发者具有很高的参考价值。它首先介绍了C++的基础概念，如变量、控制流、函数、类和对象等。接着，逐步深入到面向对象编程的概念，如继承、多态性和封装。此外，书中还涵盖了模板，这是C++的一个强大特性，允许进行泛型编程。在内存管理方面，Stroustrup讲解了动态内存分配、智能指针和内存安全的重要性，这些都是C++程序员必须掌握的关键技能。书中还讨论了异常处理，这是处理程序运行时错误的标准机制，以及如何编写健壮的代码来应对可能的异常情况。标准模板库（STL）是C++库的一部分，包括容器（如vector和list）、迭代器、算法和函数对象，提供了高效且可重用的代码。Stroustrup在书中详细解释了如何使用STL来编写高效、模块化的程序。本书还强调了设计模式和软件工程实践，包括设计原则、接口设计、测试驱动开发（TDD）和代码重构，这些对于构建大规模、可维护的C++项目至关重要。最后，考虑到C++与C的紧密关系，书中也涉及了C++与C的互操作性，帮助读者理解如何在C++程序中无缝集成C代码。《C++ Programming Language》是C++学习者的必备参考书，它提供了一个全面、权威的视角，让读者能够掌握C++的所有核心概念和技术，并为实际编程挑战做好准备。

Section 1.1.1 Examples and References 5

1.1.1 Examples and References

This book emphasizes program organization rather than the writing of algorithms. Consequently, I

avoid clever or harder-to-understand algorithms. A trivial algorithm is typically better suited to

illustrate an aspect of the language definition or a point about program structure. For example, I

use a Shell sort where, in real code, a quicksort would be better. Often, reimplementation with a

more suitable algorithm is an exercise. In real code, a call of a library function is typically more

appropriate than the code used here for illustration of language features.

Textbook examples necessarily give a warped view of software development. By clarifying and

simplifying the examples, the complexities that arise from scale disappear. I see no substitute for

writing realistically-sized programs for getting an impression of what programming and a program-

ming language are really like. This book concentrates on the language features, the basic tech-

niques from which every program is composed, and the rules for composition.

The selection of examples reflects my background in compilers, foundation libraries, and simu-

lations. Examples are simplified versions of what is found in real code. The simplification is nec-

essary to keep programming language and design points from getting lost in details. There are no

‘‘cute’’ examples without counterparts in real code. Wherever possible, I relegated to Appendix C

language-technical examples of the sort that use variables named x x and y y, types called A A and B B, and

functions called f f() and g g().

In code examples, a proportional-width font is used for identifiers. For example:

#i in nc cl lu ud de e<i io os st tr re ea am m>

i in nt t m ma ai in n()

{

s st td d: :c co ou ut t << "H He el ll lo o, n ne ew w w wo or rl ld d!\ \n n";

}

At first glance, this presentation style will seem ‘‘unnatural’’ to programmers accustomed to seeing

code in constant-width fonts. However, proportional-width fonts are generally regarded as better

than constant-width fonts for presentation of text. Using a proportional-width font also allows me

to present code with fewer illogical line breaks. Furthermore, my experiments show that most peo-

ple find the new style more readable after a short while.

Where possible, the C

language and library features are presented in the context of their use

rather than in the dry manner of a manual. The language features presented and the detail in which

they are described reflect my view of what is needed for effective use of C

. A companion, The

Annotated C

Language Standard, authored by Andrew Koenig and myself, is the complete defi-

nition of the language together with comments aimed at making it more accessible. Logically,

there ought to be another companion, The Annotated C

Standard Library. However, since both

time and my capacity for writing are limited, I cannot promise to produce that.

References to parts of this book are of the form §2.3.4 (Chapter 2, section 3, subsection 4),

§B.5.6 (Appendix B, subsection 5.6), and §6.6[10] (Chapter 6, exercise 10). Italics are used spar-

ingly for emphasis (e.g., ‘‘a string literal is not acceptable’’), for first occurrences of important con-

cepts (e.g., polymorphism), for nonterminals of the C

grammar (e.g., for-statement), and for com-

ments in code examples. Semi-bold italics are used to refer to identifiers, keywords, and numeric

values from code examples (e.g., c co ou un nt te er r, c cl la as ss s, and 1 17 71 12 2).

The C++ Programming Language, Special Edition by Bjarne Stroustrup. Copyright 2000 by AT&T.

6 Notes to the Reader Chapter 1

1.1.2 Exercises

Exercises are found at the ends of chapters. The exercises are mainly of the write-a-program vari-

ety. Always write enough code for a solution to be compiled and run with at least a few test cases.

The exercises vary considerably in difficulty, so they are marked with an estimate of their diffi-

culty. The scale is exponential so that if a (∗1) exercise takes you ten minutes, a (∗2) might take an

hour, and a (∗3) might take a day. The time needed to write and test a program depends more on

your experience than on the exercise itself. A (∗1) exercise might take a day if you first have to get

acquainted with a new computer system in order to run it. On the other hand, a (∗5) exercise might

be done in an hour by someone who happens to have the right collection of programs handy.

Any book on programming in C can be used as a source of extra exercises for Part I. Any book

on data structures and algorithms can be used as a source of exercises for Parts II and III.

1.1.3 Implementation Note

The language used in this book is ‘‘pure C

’’ as defined in the C

standard [C

,1998]. There-

fore, the examples ought to run on every C

implementation. The major program fragments in

this book were tried using several C

implementations. Examples using features only recently

adopted into C

didn’t compile on every implementation. However, I see no point in mentioning

which implementations failed to compile which examples. Such information would soon be out of

date because implementers are working hard to ensure that their implementations correctly accept

every C

feature. See Appendix B for suggestions on how to cope with older C

compilers and

with code written for C compilers.

1.2 Learning C

The most important thing to do when learning C

is to focus on concepts and not get lost in

language-technical details. The purpose of learning a programming language is to become a better

programmer; that is, to become more effective at designing and implementing new systems and at

maintaining old ones. For this, an appreciation of programming and design techniques is far more

important than an understanding of details; that understanding comes with time and practice.

supports a variety of programming styles. All are based on strong static type checking, and

most aim at achieving a high level of abstraction and a direct representation of the programmer’s

ideas. Each style can achieve its aims effectively while maintaining run-time and space efficiency.

A programmer coming from a different language (say C, Fortran, Smalltalk, Lisp, ML, Ada, Eiffel,

Pascal, or Modula-2) should realize that to gain the benefits of C

, they must spend time learning

and internalizing programming styles and techniques suitable to C

. The same applies to pro-

grammers used to an earlier and less expressive version of C

Thoughtlessly applying techniques effective in one language to another typically leads to awk-

ward, poorly performing, and hard-to-maintain code. Such code is also most frustrating to write

because every line of code and every compiler error message reminds the programmer that the lan-

guage used differs from ‘‘the old language.’’ You can write in the style of Fortran, C, Smalltalk,

etc., in any language, but doing so is neither pleasant nor economical in a language with a different

philosophy. Every language can be a fertile source of ideas of how to write C

programs.

The C++ Programming Language, Special Edition by Bjarne Stroustrup. Copyright 2000 by AT&T.

Section 1.2 Learning C

However, ideas must be transformed into something that fits with the general structure and type

system of C

in order to be effective in the different context. Over the basic type system of a lan-

guage, only Pyrrhic victories are possible.

supports a gradual approach to learning. How you approach learning a new programming

language depends on what you already know and what you aim to learn. There is no one approach

that suits everyone. My assumption is that you are learning C

to become a better programmer

and designer. That is, I assume that your purpose in learning C

is not simply to learn a new syn-

tax for doing things the way you used to, but to learn new and better ways of building systems.

This has to be done gradually because acquiring any significant new skill takes time and requires

practice. Consider how long it would take to learn a new natural language well or to learn to play a

new musical instrument well. Becoming a better system designer is easier and faster, but not as

much easier and faster as most people would like it to be.

It follows that you will be using C

– often for building real systems – before understanding

every language feature and technique. By supporting several programming paradigms (Chapter 2),

supports productive programming at several levels of expertise. Each new style of program-

ming adds another tool to your toolbox, but each is effective on its own and each adds to your

effectiveness as a programmer. C

is organized so that you can learn its concepts in a roughly lin-

ear order and gain practical benefits along the way. This is important because it allows you to gain

benefits roughly in proportion to the effort expended.

In the continuing debate on whether one needs to learn C before C

, I am firmly convinced

that it is best to go directly to C

. C

is safer, more expressive, and reduces the need to focus on

low-level techniques. It is easier for you to learn the trickier parts of C that are needed to compen-

sate for its lack of higher-level facilities after you have been exposed to the common subset of C

and C

and to some of the higher-level techniques supported directly in C

. Appendix B is a

guide for programmers going from C

to C, say, to deal with legacy code.

Several independently developed and distributed implementations of C

exist. A wealth of

tools, libraries, and software development environments are also available. A mass of textbooks,

manuals, journals, newsletters, electronic bulletin boards, mailing lists, conferences, and courses

are available to inform you about the latest developments in C

, its use, tools, libraries, implemen-

tations, etc. If you plan to use C

seriously, I strongly suggest that you gain access to such

sources. Each has its own emphasis and bias, so use at least two. For example, see [Barton,1994],

[Booch,1994], [Henricson,1997], [Koenig,1997], [Martin,1995].

1.3 The Design of C

Simplicity was an important design criterion: where there was a choice between simplifying the

language definition and simplifying the compiler, the former was chosen. However, great impor-

tance was attached to retaining a high degree of compatibility with C [Koenig,1989] [Strous-

trup,1994] (Appendix B); this precluded cleaning up the C syntax.

has no built-in high-level data types and no high-level primitive operations. For example,

the C

language does not provide a matrix type with an inversion operator or a string type with a

concatenation operator. If a user wants such a type, it can be defined in the language itself. In fact,

defining a new general-purpose or application-specific type is the most fundamental programming

The C++ Programming Language, Special Edition by Bjarne Stroustrup. Copyright 2000 by AT&T.

8 Notes to the Reader Chapter 1

activity in C

. A well-designed user-defined type differs from a built-in type only in the way it is

defined, not in the way it is used. The C

standard library described in Part III provides many

examples of such types and their uses. From a user’s point of view, there is little difference

between a built-in type and a type provided by the standard library.

Features that would incur run-time or memory overheads even when not used were avoided in

the design of C

. For example, constructs that would make it necessary to store ‘‘housekeeping

information’’ in every object were rejected, so if a user declares a structure consisting of two 16-bit

quantities, that structure will fit into a 32-bit register.

was designed to be used in a traditional compilation and run-time environment, that is, the

C programming environment on the UNIX system. Fortunately, C

was never restricted to UNIX;

it simply used UNIX and C as a model for the relationships between language, libraries, compilers,

linkers, execution environments, etc. That minimal model helped C

to be successful on essen-

tially every computing platform. There are, however, good reasons for using C

in environments

that provide significantly more support. Facilities such as dynamic loading, incremental compila-

tion, and a database of type definitions can be put to good use without affecting the language.

type-checking and data-hiding features rely on compile-time analysis of programs to pre-

vent accidental corruption of data. They do not provide secrecy or protection against someone who

is deliberately breaking the rules. They can, however, be used freely without incurring run-time or

space overheads. The idea is that to be useful, a language feature must not only be elegant; it must

also be affordable in the context of a real program.

For a systematic and detailed description of the design of C

, see [Stroustrup,1994].

1.3.1 Efficiency and Structure

was developed from the C programming language and, with few exceptions, retains C as a

subset. The base language, the C subset of C

, is designed to ensure a very close correspondence

between its types, operators, and statements and the objects that computers deal with directly: num-

bers, characters, and addresses. Except for the n ne ew w, d de el le et te e, t ty yp pe ei id d, d dy yn na am mi ic c_ _c ca as st t, and t th hr ro ow w oper-

ators and the try-block, individual C

expressions and statements need no run-time support.

can use the same function call and return sequences as C – or more efficient ones. When

even such relatively efficient mechanisms are too expensive, a C

function can be substituted

inline, so that we can enjoy the notational convenience of functions without run-time overhead.

One of the original aims for C was to replace assembly coding for the most demanding systems

programming tasks. When C

was designed, care was taken not to compromise the gains in this

area. The difference between C and C

is primarily in the degree of emphasis on types and struc-

ture. C is expressive and permissive. C

is even more expressive. However, to gain that increase

in expressiveness, you must pay more attention to the types of objects. Knowing the types of

objects, the compiler can deal correctly with expressions when you would otherwise have had to

specify operations in painful detail. Knowing the types of objects also enables the compiler to

detect errors that would otherwise persist until testing – or even later. Note that using the type sys-

tem to check function arguments, to protect data from accidental corruption, to provide new types,

to provide new operators, etc., does not increase run-time or space overheads in C

The emphasis on structure in C

reflects the increase in the scale of programs written since C

was designed. You can make a small program (say, 1,000 lines) work through brute force even

The C++ Programming Language, Special Edition by Bjarne Stroustrup. Copyright 2000 by AT&T.

Section 1.3.1 Efficiency and Structure 9

when breaking every rule of good style. For a larger program, this is simply not so. If the structure

of a 100,000-line program is bad, you will find that new errors are introduced as fast as old ones are

removed. C

was designed to enable larger programs to be structured in a rational way so that it

would be reasonable for a single person to cope with far larger amounts of code. In addition, the

aim was to have an average line of C

code express much more than the average line of C or Pas-

cal code. C

has by now been shown to over-fulfill these goals.

Not every piece of code can be well-structured, hardware-independent, easy-to-read, etc. C

possesses features that are intended for manipulating hardware facilities in a direct and efficient

way without regard for safety or ease of comprehension. It also possesses facilities for hiding such

code behind elegant and safe interfaces.

Naturally, the use of C

for larger programs leads to the use of C

by groups of program-

mers. C

’s emphasis on modularity, strongly typed interfaces, and flexibility pays off here. C

has as good a balance of facilities for writing large programs as any language has. However, as

programs get larger, the problems associated with their development and maintenance shift from

being language problems to more global problems of tools and management. Part IV explores

some of these issues.

This book emphasizes techniques for providing general-purpose facilities, generally useful

types, libraries, etc. These techniques will serve programmers of small programs as well as pro-

grammers of large ones. Furthermore, because all nontrivial programs consist of many semi-

independent parts, the techniques for writing such parts serve programmers of all applications.

You might suspect that specifying a program by using a more detailed type structure would lead

to a larger program source text. With C

, this is not so. A C

program declaring function argu-

ment types, using classes, etc., is typically a bit shorter than the equivalent C program not using

these facilities. Where libraries are used, a C

program will appear much shorter than its C equiv-

alent, assuming, of course, that a functioning C equivalent could have been built.

1.3.2 Philosophical Note

A programming language serves two related purposes: it provides a vehicle for the programmer to

specify actions to be executed, and it provides a set of concepts for the programmer to use when

thinking about what can be done. The first purpose ideally requires a language that is ‘‘close to the

machine’’ so that all important aspects of a machine are handled simply and efficiently in a way

that is reasonably obvious to the programmer. The C language was primarily designed with this in

mind. The second purpose ideally requires a language that is ‘‘close to the problem to be solved’’

so that the concepts of a solution can be expressed directly and concisely. The facilities added to C

to create C

were primarily designed with this in mind.

The connection between the language in which we think/program and the problems and solu-

tions we can imagine is very close. For this reason, restricting language features with the intent of

eliminating programmer errors is at best dangerous. As with natural languages, there are great ben-

efits from being at least bilingual. A language provides a programmer with a set of conceptual

tools; if these are inadequate for a task, they will simply be ignored. Good design and the absence

of errors cannot be guaranteed merely by the presence or the absence of specific language features.

The type system should be especially helpful for nontrivial tasks. The C

class concept has, in

fact, proven itself to be a powerful conceptual tool.

The C++ Programming Language, Special Edition by Bjarne Stroustrup. Copyright 2000 by AT&T.

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C++编程语言第三版 - Bjarne Stroustrup

The_C_Programming_Language.pdf

the c programming language.pdf

The C Programming Language.pdf

编写一个C语言程序，定义一个函数，求 1+1/2+1/3+......+1/n。并在主程序中调用它，求1+1/2+1/3+......+1/19

c语言代码实现下面功能:1. 使用 for 语句计算 1+4+7+...+100 的值并输出结果。 2. 使用 while 语句计算 2+4+6+...+500 的值并输出结果。 3. 使用 do...while 语句计算 1+2+4+8+...+1024 的值并输出结果。

1+1/2+1/3+......+1/99+1/100用c语言程序表示

1.写出以下式子的算法过程的C从程序。 1) 1+1/2+13+....+1/100; 2) 1/2* 2/3*3/4*..*99/100

输入整数n，求1+1/3+1/5+......1/(2n+1) 输入格式: "%d" 输出格式: "%.3f"

Write a program in C to calculate the sum of numbers from 1 to n using recursion. Input: Input a positve integer n. Output : Compute the summation of 1+2+...+n. Sample of Input: 5 Sample of Output: 15

c 实现1+1/2+1/3+....+n

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1.写出以下式子的算法过程的C从程序。 1) 1+1/2+13+....+1/100; 2) 1/2* 2/33/4..*99/100