C语言编程权威指南

需积分: 0 108 浏览量更新于2024-07-25 收藏 897KB PDF 举报

"C语言经典教程——《THE C PROGRAMMING LANGUAGE》" 《THE C PROGRAMMING LANGUAGE》是由C语言的设计者Brian W. Kernighan和Dennis M. Ritchie共同编著的一本权威指南，这本书首次出版于1988年，是C语言学习者的必读之作。书中详细阐述了C语言的基础概念、语法以及编程实践，旨在帮助读者深入理解和掌握C语言的核心知识。 1. **简介与教程部分** - 开篇的"Getting Started"引导初学者进入C语言的世界，讲解如何设置环境并编写第一个简单的程序。 - "Variables and Arithmetic Expressions"章节介绍变量的概念和基本算术运算，这是理解任何编程语言的基础。 - "The for statement"详述C语言中的循环结构，它是控制程序流程的关键。 - "Symbolic Constants"让读者了解如何使用宏定义常量，提高代码可读性。 - "Character Input and Output"部分则涉及字符输入输出，通过实例展示了如何处理标准输入输出。 - 书中还提供了一些实用小程序的示例，如文件复制、字符计数、行计数和单词计数，这些例子有助于读者实践和巩固学到的知识。 - "Arrays"、"Functions"、"Arguments - Call by Value"等章节进一步深入到数组、函数调用和参数传递，这些都是C语言的重要特性。 - "Character Arrays"、"External Variables and Scope"讲解字符数组（如字符串）的使用以及外部变量的作用域规则。 2. **类型、运算符和表达式** - "Variable Names"讨论了变量命名的规则和最佳实践。 - "Data Types and Sizes"涵盖了C语言的数据类型及其内存占用。 - "Constants"介绍了如何声明常量，包括整型、浮点型和字符型。 - "Declarations"讲解变量声明的语法和规则。 - "Arithmetic Operators"列出了所有的算术运算符，如加减乘除等。 - "Relational and Logical Operators"涉及比较和逻辑运算符，用于条件判断和逻辑组合。 - "Type Conversions"解释了自动类型转换和强制类型转换的过程。 - "Increment and Decrement Operators"（自增自减运算符）是C语言中的特殊运算符，用于快速改变变量的值。 - "Bitwise Operators"介绍了位操作，对于底层数据处理和硬件交互非常有用。 - "Assignment Operators and Expressions"讲述了赋值运算符以及它们在表达式中的使用。 - "Conditional Expressions"是三目运算符，允许在表达式中根据条件选择值。 - "Precedence and Order of Evaluation"讲解运算符的优先级和求值顺序，确保正确理解表达式的计算过程。 3. **控制流** - "Statements and Blocks"介绍了各种语句，如if-else、switch以及代码块的组织方式。 - "Loops"涵盖了while、do-while和for循环，以及如何跳出循环。 - "Break and Continue"讲解了这两个特殊的控制流程语句，用于中断循环。 - "Functions"的进一步讨论，包括递归函数和函数指针，这些都是C语言的高级特性。 - "Compound Statements"和"Nested If"揭示了如何构建复杂的控制结构。 - "Goto Statement"虽然不推荐使用，但仍然在某些场合下有其价值。 - "Switch Statement"提供了另一种条件控制的选择，通常用于多分支选择。这本书不仅对C语言的基础进行了全面覆盖，而且深入探讨了许多高级主题，适合所有级别的C语言学习者。通过阅读和实践书中的例子，读者将能够熟练地编写高效且可靠的C语言程序。

Chapter 1 - A Tutorial Introduction

to print this sequence of characters

} \n represents the newline character

The first C program

The statements of a function are enclosed in braces { }. The function main contains only one statement,

printf("hello, world\n");

A function is called by naming it, followed by a parenthesized list of arguments, so this calls the function printf

with the argument "hello, world\n". printf is a library function that prints output, in this case the string

of characters between the quotes.

A sequence of characters in double quotes, like "hello, world\n", is called a character string or string

constant. For the moment our only use of character strings will be as arguments for printf and other functions.

The sequence \n in the string is C notation for the newline character, which when printed advances the output to

the left margin on the next line. If you leave out the \n (a worthwhile experiment), you will find that there is no

line advance after the output is printed. You must use \n to include a newline character in the printf argument;

if you try something like

printf("hello, world

");

the C compiler will produce an error message.

printf never supplies a newline character automatically, so several calls may be used to build up an output line

in stages. Our first program could just as well have been written

#include <stdio.h>

main()

{

printf("hello, ");

printf("world");

printf("\n");

}

to produce identical output.

Notice that \n represents only a single character. An escape sequence like \n provides a general and extensible

mechanism for representing hard-to-type or invisible characters. Among the others that C provides are \t for tab,

\b for backspace, \" for the double quote and \\ for the backslash itself. There is a complete list in

Section 2.3.

http://freebooks.by.ru/view/CProgrammingLanguage/chapter1.html(3of30)[9/6/200212:21:11]

Chapter 1 - A Tutorial Introduction

which set the variables to their initial values. Individual statements are terminated by semicolons.

Each line of the table is computed the same way, so we use a loop that repeats once per output line; this is the

purpose of the while loop

while (fahr <= upper) {

...

}

The while loop operates as follows: The condition in parentheses is tested. If it is true (fahr is less than or equal

to upper), the body of the loop (the three statements enclosed in braces) is executed. Then the condition is re-

tested, and if true, the body is executed again. When the test becomes false (fahr exceeds upper) the loop ends,

and execution continues at the statement that follows the loop. There are no further statements in this program, so

it terminates.

The body of a while can be one or more statements enclosed in braces, as in the temperature converter, or a

single statement without braces, as in

while (i < j)

i = 2 * i;

In either case, we will always indent the statements controlled by the while by one tab stop (which we have

shown as four spaces) so you can see at a glance which statements are inside the loop. The indentation emphasizes

the logical structure of the program. Although C compilers do not care about how a program looks, proper

indentation and spacing are critical in making programs easy for people to read. We recommend writing only one

statement per line, and using blanks around operators to clarify grouping. The position of braces is less important,

although people hold passionate beliefs. We have chosen one of several popular styles. Pick a style that suits you,

then use it consistently.

Most of the work gets done in the body of the loop. The Celsius temperature is computed and assigned to the

variable celsius by the statement

celsius = 5 * (fahr-32) / 9;

The reason for multiplying by 5 and dividing by 9 instead of just multiplying by 5/9 is that in C, as in many other

languages, integer division truncates: any fractional part is discarded. Since 5 and 9 are integers. 5/9 would be

truncated to zero and so all the Celsius temperatures would be reported as zero.

This example also shows a bit more of how printf works. printf is a general-purpose output formatting

function, which we will describe in detail in

Chapter 7. Its first argument is a string of characters to be printed,

with each % indicating where one of the other (second, third, ...) arguments is to be substituted, and in what form it

is to be printed. For instance, %d specifies an integer argument, so the statement

printf("%d\t%d\n", fahr, celsius);

http://freebooks.by.ru/view/CProgrammingLanguage/chapter1.html(6of30)[9/6/200212:21:11]

Chapter 1 - A Tutorial Introduction

causes the values of the two integers fahr and celsius to be printed, with a tab (\t) between them.

Each % construction in the first argument of printf is paired with the corresponding second argument, third

argument, etc.; they must match up properly by number and type, or you will get wrong answers.

By the way, printf is not part of the C language; there is no input or output defined in C itself. printf is just a

useful function from the standard library of functions that are normally accessible to C programs. The behaviour of

printf is defined in the ANSI standard, however, so its properties should be the same with any compiler and

library that conforms to the standard.

In order to concentrate on C itself, we don't talk much about input and output until

chapter 7. In particular, we will

defer formatted input until then. If you have to input numbers, read the discussion of the function scanf in

Section 7.4. scanf is like printf, except that it reads input instead of writing output.

There are a couple of problems with the temperature conversion program. The simpler one is that the output isn't

very pretty because the numbers are not right-justified. That's easy to fix; if we augment each %d in the printf

statement with a width, the numbers printed will be right-justified in their fields. For instance, we might say

printf("%3d %6d\n", fahr, celsius);

to print the first number of each line in a field three digits wide, and the second in a field six digits wide, like this:

0 -17

20 -6

40 4

60 15

80 26

100 37

...

The more serious problem is that because we have used integer arithmetic, the Celsius temperatures are not very

accurate; for instance, 0

F is actually about -17.8

C, not -17. To get more accurate answers, we should use floating-

point arithmetic instead of integer. This requires some changes in the program. Here is the second version:

#include <stdio.h>

/* print Fahrenheit-Celsius table

for fahr = 0, 20, ..., 300; floating-point version */

main()

{

float fahr, celsius;

float lower, upper, step;

lower = 0; /* lower limit of temperatuire scale */

upper = 300; /* upper limit */

step = 20; /* step size */

http://freebooks.by.ru/view/CProgrammingLanguage/chapter1.html(7of30)[9/6/200212:21:11]

剩余294页未读，继续阅读

天天上上

粉丝: 0
资源: 1

C语言编程权威指南

《the c programming language》(CLH)

The C Programming Language(2nd Edition) 中文完整版PDF

The C Programming Language

the c programming language

The C programming Language

The C Programming language

the C Programming language

The C programming language

【机器人】将ChatGPT飞书机器人钉钉机器人企业微信机器人公众号部署到vercel及docker_pgj.zip

图数据分析中基于对比学习的异常检测算法的Python实现及应用-含代码及详细解释说明

最新资源