第四章Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.l l主要内容主要内容4.1 C语句概述4.2 赋值语句4.3 数据输入输出的概念及在c语言中的实现4.4 字符数据的输入输出4.5 格式输入与输出4.6 顺序结构程序设计举例Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述C程序源程序文件1源程序文件2源程序文件n预处理命令函数n函数1数据声明函数首部函数体数据声明执行语句Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 一个c程序可以有若干个源程序文件组成 一个源文件可以有若干个函数和预处理命令 以及全局变量声明部分组成(第八章内容） 一个函数有函数首部和函数体组成 函数体由数据声明和执行语句组成 C语句分为5类控制语句 函数调用语句 表达式语句 空语句 复合语句Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 (一)控制语句 完成一定的控制功能1 if() else 条件语句 6 break 间断语句 2 for() 循环语句 7 switch() 开关语句 3 while()循环语句 8 goto 转向语句 4 do while();循环语句 9 return 返回语句 5 continue 继续语句Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 (二)函数调用语句有一个函数调用加一个分号构成一个语句Printf(“This is a C statement.”);Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 (三)表达式语句有一个表达式加一个分号构成一个语句a = 3 ;分号赋值表达式表达式语句Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 (四)空语句 只有一个分号的语句（什么也不做） 用来作为循环语句中的循环体Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.1 C语句概述 (五）复合语句 用一对括起来的语句z=x+y; t=z/100; printf(“%f”,t); Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.2 赋值语句赋值语句是由赋值表达式加上一个分号构成 例：a=100 赋值表达式 a=100; 赋值语句If后面的括号中是一个“条件”,赋值表达式 可以包含于条件表达式中，如：if(a=b)0) t=a; Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.2 赋值语句 1 1：C语言中的赋值号“=”是一个运算符, 在其他大多数语言中赋值号不是运算符.2 2：其他大多数高级语言没有“赋值表达式 ”这一概念.问题：问题：c c语言中的赋值语句与其他高级语言语言中的赋值语句与其他高级语言 的赋值语句有什么不同点的赋值语句有什么不同点? ? Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.3 数据输入输出的概念及在C语言中的实现 (一).所谓输入输出是以计算机主机为主体而言的输出:从计算机向外部输出设备(显示器,打印机)输出数据 输入:从输入设备(键盘,鼠标,扫描仪)向计算机输入数据.Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.(二).C语言本身不提供输入输出语句,输入和输出 操作是由C函数库中的函数来实现的 例如: 字符输入函数: getchar 字符输出函数:putchar 格式输入函数: scanf 格式输出函数: printf 字符串输入函数:gets 字数穿输出函数:puts4.3 数据输入输出的概念及在C语言中的实现Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.(三).在使用系统库函数时,要用预编译命令 “#include”将有关的“头文件”包括到用户源 文件中. 例如：在调用标准输入输出库函数时，文件开头应 该有：#include “stdio.h”或：#include 头文 件4.3 数据输入输出的概念及在C语言中的实现Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.4.4 字符数据的输入输出（一）.字符输出函数 一般形式：putchar（c） 函数作用：向终端输出一个字符字符型变量 或常量 整型变量Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.