C基础

定义一个循环变量<br>for（表达式1；表达式2；表达式3）<br>{<br>&nbsp;语句块；（循环体）<br>}<br>表达式1：给循环变量赋初始值<br>表达式2：循环条件也是结束循环的条件<br>表达式3：递增或递减<br>

嵌套结构<br>

定义一个循环变量<br>while（判断条件）<br>{<br>&nbsp;语句块；<br>&nbsp;递增或递减；<br>}<br>

do&nbsp;while

break：直接跳出整个循环（程序）<br>

continue：跳出循环，只跳出当前循环

while（1）<br>{<br>}<br>

<br>&nbsp;while(1)&nbsp;;<br>

for（；；）<br>{<br><br>}&nbsp;&nbsp;<br>

if（表达式）<br>{<br>&nbsp;语句块1；<br>}<br>else<br>{<br>&nbsp;语句块2；<br>}<br>

switch（表达式或常量）<br>{<br>case&nbsp;常量1：<br>&nbsp;语句块1；<br>&nbsp;break；<br>case&nbsp;常量2：<br>&nbsp;语句块2；<br>&nbsp;break；<br>……<br>defeult：<br>&nbsp;语句块N；<br>&nbsp;break；<br>}<br>

getchar

putchar<br>

printf<br>

scanf

回收垃圾字符<br>

字符型常量<br>

字符串常量<br>

整型常量

浮点型常量

指数常量

标识常量

打开

关闭

查看

新建

复制

剪切

路径切换

放大终端：Ctrl&nbsp;Shift&nbsp;+

缩小终端：Ctrl&nbsp;-

历史命令：上下键

清屏：Ctrl&nbsp;l

自动补全：Tab

插入模式

命令行模式

底行模式

命令：gcc&nbsp;-E&nbsp;hello.c&nbsp;-o&nbsp;hello.i<br>删除文件中的注释&nbsp;展开头文件&nbsp;替换宏定义

命令：gcc -S hello.i -o hello.s<br style="-webkit-font-smoothing: antialiased;">检查语法错误 有错报错 没有错误生成汇编语言

命令：gcc&nbsp;-c&nbsp;hello.s&nbsp;-o&nbsp;hello.o<br>将汇编语言转化成二进制的文件

命令：gcc&nbsp;hello.o&nbsp;-o&nbsp;hello<br>链接库文件，生成可执行文件

存储类型：auto自动&nbsp;&nbsp;static静态&nbsp;&nbsp;extern引用外部&nbsp;&nbsp;register寄存器<br>数据类型：char&nbsp;&nbsp;int&nbsp;&nbsp;long&nbsp;&nbsp;short&nbsp;&nbsp;float&nbsp;&nbsp;&nbsp;double&nbsp;&nbsp;signed有符号&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;unsigned无符号<br>构造类型：struct&nbsp;&nbsp;union&nbsp;&nbsp;enum<br>选择类型：if&nbsp;&nbsp;else&nbsp;&nbsp;switch&nbsp;&nbsp;case&nbsp;&nbsp;default<br>循环类型：for&nbsp;while&nbsp;goto&nbsp;do&nbsp;&nbsp;break&nbsp;&nbsp;continue<br>其它&nbsp;：void&nbsp;&nbsp;typedef&nbsp;&nbsp;const&nbsp;&nbsp;sizeof&nbsp;&nbsp;return&nbsp;&nbsp;volatile<br>

定义：用于标识变量&nbsp;宏定义&nbsp;函数名

命名规范：<br>由数字，字母，下划线组成<br>不能以数字开头<br>不能和关键字重名<br>见名知义

算术运算符

逻辑运算符

位运算符

关系运算符

赋值运算符

三目运算符

运算符的优先级<br>

换行&nbsp;&nbsp;空格&nbsp;&nbsp;tab<br>

，&nbsp; ；&nbsp; (&nbsp;)&nbsp; &nbsp;{&nbsp;}&nbsp; &nbsp;[&nbsp;]<br>

转八进制

转十进制

转十六进制

转二进制

以0开头

转二进制

转二进制

0-9&nbsp;a-f

以0x开头

ASCII值&nbsp;&nbsp;在终端输入man&nbsp;ascii查看ASCII表，按q键退出

全局变量：在函数外声明的变量，变量可以在全局使用<br>

局部变量：在函数内声明的变量，只能在函数内部使用<br>

&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 局部变量&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;全局变量<br>定义位置&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;函数内部&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;函数外部<br>作用域&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;在声明函数内可以使用&nbsp; &nbsp; &nbsp; 全局可用<br>初始值（未赋值）&nbsp; &nbsp; 随机值&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;值为0<br>存储位置&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 栈区&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 全局区<br>生命周期&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 和定义函数共存亡&nbsp; &nbsp; &nbsp;和整个程序共存亡<br>

cahr&nbsp; &nbsp; &nbsp; &nbsp; 字符型&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;1个字节<br>int&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;整型&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4个字节<br>short&nbsp; &nbsp; &nbsp; 短整型&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2个字节<br>long&nbsp; &nbsp; &nbsp; &nbsp;长整型&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4个字节<br>float&nbsp; &nbsp; &nbsp; &nbsp;单精度浮点型&nbsp; &nbsp; &nbsp; 4个字节<br>double&nbsp; &nbsp; 双精度浮点型&nbsp; &nbsp; &nbsp;8个字节<br>