C语言教程:从入门到精通

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"C语言教程,适合初学者的入门书籍,涵盖了C语言的基础知识,包括数据类型、运算符、控制结构、数组、函数、编译预处理、指针、结构体、位运算和文件操作等内容。" C语言是计算机编程的基础之一,广泛应用于系统开发、嵌入式系统、软件工程等多个领域。对于初学者而言,了解C语言概述是学习的首要步骤。程序设计是通过编写代码来指导计算机执行特定任务的过程,这些代码最终会被转换为计算机能够理解的机器语言。 C语言是一种中级语言,介于硬件层面的低级语言(如机器语言和汇编语言)和更抽象的高级语言之间。它的语法简洁明了,同时提供了对底层硬件的直接访问,这使得C语言在效率和灵活性上具有优势。 在C语言中,程序通常以文本文件形式存在,扩展名为.c。当执行C程序时,需要先通过编译过程将其转换为机器语言。这个过程由编译器完成,它将源代码文件(.c)编译成目标文件(.obj),目标文件是包含了可执行机器指令的二进制文件。如果多个源文件一起编译,它们会链接成一个可执行文件(.exe),这样就可以在DOS或Windows环境下直接运行。 C语言中的基本元素包括数据类型,如整型(int)、浮点型(float)、字符型(char)等,以及运算符,如算术运算符(+, -, *, /, %)、关系运算符(==, !=, <, >, <=, >=)、逻辑运算符(&&, ||, !)等。程序的控制流程由逻辑运算和判断选取控制(如if...else语句)、循环控制(如for, while, do...while循环)构成。 数组是C语言中存储一组相同类型数据的集合,而函数则是实现模块化程序设计的关键,可以封装特定功能并重复使用。编译预处理包括宏定义(#define)、条件编译(#ifdef, #ifndef, #endif)等,用于在编译阶段进行文本替换和条件判断。 指针是C语言的一大特色,它允许程序直接操作内存地址,提高了代码的灵活性和效率。结构体(struct)和共同体(union)则允许我们将不同类型的数据组合在一起,形成复合数据类型。位运算操作符(&, |, ^, ~, <<, >>)则可以直接操作二进制位,常用于低级别的数据操作。 最后,C语言支持文件操作,包括读取和写入文件,这对于数据持久化和程序间通信至关重要。C语言是一门强大的编程语言,它的学习不仅是技术技能的提升,也是理解计算机工作原理的重要途径。
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C Programming.pdf Contents Computers 1 An Introduction to Computers........................................................................................1 Hardware and Software ....................................................................................1 Data and Information .......................................................................................2 Data Processing................................................................................................2 Programming Languages 4 What is Programming? ..................................................................................................4 From Problem to Program ................................................................................5 Programming Languages ...............................................................................................8 C 8 A look at C ....................................................................................................................8 Making C Run..................................................................................................9 Creating C Programs........................................................................................9 What Comprises a C Program?.......................................................................10 The Advantages of C ......................................................................................11 The Disadvantages of C..................................................................................11 A First C Program 11 The Program Example .................................................................................................11 #include ........................................................................................................12 <stdio.h>.......................................................................................................12 void ...............................................................................................................12 main ..............................................................................................................13 ( void )...........................................................................................................13 { .....................................................................................................................13 float ...............................................................................................................13 height, width, area, wood_length................................................................13 ; .....................................................................................................................14 scanf .............................................................................................................14 ( .....................................................................................................................14 "%f", ..............................................................................................................14 &height..........................................................................................................15 ) ; ...................................................................................................................15 scanf ( "%f", &width ) ;.................................................................................15 area = 2 * height * width ;............................................................................15 wood_length = 2 * ( height + width ) * 3.25 ;.................................................16 printf..............................................................................................................16 ( "The area of glass needed is : %f metres.\n",.........................................16 area ) ; ..........................................................................................................17 printf ( "The length of wood needed is : %f feet.\n", wood_length ) ; ......17 } .....................................................................................................................17 Punctuation ....................................................................................................17 Variables 18 ii Variables and Data .........................................................................................18 Types of Variables .......................................................................................................18 Declaration ..................................................................................................................18 int variables....................................................................................................19 float variables ................................................................................................19 char variables ................................................................................................19 Missing Types ................................................................................................19 Variable Declaration ....................................................................................................19 Giving Values to Variables ..........................................................................................20 Expressions ....................................................................................................21 Types of Data in Expressions..........................................................................22 Getting Values into the Program ..................................................................................23 Writing a Program 24 Comments......................................................................................................24 Program Flow ..............................................................................................................24 Conditional Execution - if...............................................................................25 Conditions and Relational Operators ..............................................................26 Combining Logical Operators.........................................................................27 Lumping Code Together.................................................................................27 Magic Numbers and #define..........................................................................28 Loops .............................................................................................................29 Breaking Out of Loops ...................................................................................32 Going Back to the Top of a Loop ....................................................................32 More Complicated Decisions ..........................................................................33 Complete Glazing Program ............................................................................33 Operator Shorthand........................................................................................34 Statements and Values....................................................................................35 Neater Printing...............................................................................................36 Functions 37 Functions So Far ..........................................................................................................37 Function Heading ...........................................................................................37 Function Body ................................................................................................38 return .............................................................................................................38 Calling a Function..........................................................................................38 Scope .............................................................................................................39 Variables Local to Blocks ...............................................................................40 Full Functions Example..................................................................................40 Pointers.......................................................................................................................42 NULL Pointers ...............................................................................................44 Pointers and Functions ...................................................................................44 Static Variables............................................................................................................45 Arrays 46 Why We Need Arrays ..................................................................................................46 Sorting ...........................................................................................................47 Array Types and Sizes..................................................................................................49 More Than One Dimension ............................................................................50 Switching 53 Making Multiple Decisions ..........................................................................................53 Strings 55 iii How long is a piece of string?.......................................................................................55 Putting Values into Strings ..........................................................................................56 Using Strings ...............................................................................................................57 The String Library .......................................................................................................58 strcpy .............................................................................................................59 strcmp ............................................................................................................59 strlen..............................................................................................................59 Reading and Printing Strings .......................................................................................59 Bomb Proof Input.........................................................................................................60 Structures 61 What is a Structure?.....................................................................................................61 How Structures Work...................................................................................................63 Pointers to structures....................................................................................................63 Defining your own Types .............................................................................................64 Files 65 When do we use Files? .................................................................................................65 Streams and Files ...........................................................................................65 fopen and fclose ...........................................................................................................66 Mode String ...................................................................................................68 File Functions ..............................................................................................................70 fread and fwrite ..............................................................................................70 The End of the File and Errors.....................................................................................71 Memory 72 Fetching Memory.........................................................................................................72 malloc ............................................................................................................72 free.................................................................................................................73 The heap......................................................................................................................73 C and Large Programs 74 Building Large Programs in C .....................................................................................74 The Compile and Link Process .......................................................................74 Referring to External Items ............................................................................75 The Make Program.........................................................................................76 Projects ..........................................................................................................76 The C Pre-Processor.....................................................................................................77 The #include Directive ...................................................................................77 Conditional Compilation ................................................................................77 A Sample Project .........................................................................................................78 The Problem...................................................................................................78 The Data Structure .........................................................................................78 Program Files.................................................................................................79 The Most Important Bit!.................................................................................84 Glossary of Terms 93