📄 磁动力工作室－－51单片机c语言入门教程－－第四课：数据类型.htm
字号:
<TR>
<TD>
<DIV class=title1 align=center>第四课 数据类型
</DIV></TD></TR>
<TR>
<TD>
<DIV align=center>作 者： 明浩 出 处： 磁动力工作室 <A
href="http://www.cdle.net/"
target=_blank>http://www.cdle.net/</A> <A
href="mailto:pnzwzw@cdle.net">mailto:pnzwzw@cdle.net</A>(ID20)</DIV></TD></TR>
<TR>
<TD> 先来简单说说C语言的标识符和关键字。标识符是用来标识源程序中某个对象的名字的，这些对象可以是语句、数据类型、函数、变量、数组等等。C语言是大小字敏感的一种高级语言，如果我们要定义一个定时器1，可以写做"Timer1"，如果程序中有"TIMER1"，那么这两个是完全不同定义的标识符。标识符由字符串，数字和下划线等组成，注意的是第一个字符必须是字母或下划线，如"1Timer"是错误的，编译时便会有错误提示。有些编译系统专用的标识符是以下划线开头，所以一般不要以下划线开头命名标识符。标识符在命名时应当简单，含义清晰，这样有助于阅读理解程序。在C51编译器中，只支持标识符的前32位为有效标识，一般情况下也足够用了，除非你要写天书：P。<BR> 关键字则是编程语言保留的特殊标识符，它们具有固定名称和含义，在程序编写中不允许标识符与关键资亦同。在KEIL
uVision2中的关键字除了有ANSI
C标准的32个关键字外还根据51单片机的特点扩展了相关的关键字。其实在KEIL
uVision2的文本编辑器中编写C程序，系统可以把保留字以不同颜色显示，缺省颜色为天蓝色。（<A
href="http://www.cdle.net/alldata/C51/fl.htm"
target=_blank><FONT
color=#990000>标准和扩展关键字请看附录一中的附表1-1和附表1-2</FONT></A>）<BR> 先看表4－1，表中列出了KEIL
uVision2
C51编译器所支持的数据类型。在标准C语言中基本的数据类型为char,int,short,long,float和double，而在C51编译器中int和short相同，float和double相同，这里就不列出说明了。下面来看看它们的具体定义：<BR></TD></TR>
<TR>
<TD>
<TABLE
style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt"
cellSpacing=0 cellPadding=0 align=center
border=1><TBODY>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid"
vAlign=top width=189>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">数据类型<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">长 度<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt"
vAlign=top width=249>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">值 域<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD></TR>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=189>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">unsigned
char<O:P></O:P></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">单字节<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=249>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">0～255<O:P></O:P></SPAN></P></TD></TR>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=189>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">signed
char<O:P></O:P></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">单字节<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=249>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">-128～+127<O:P></O:P></SPAN></P></TD></TR>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=189>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">unsigned
int<O:P></O:P></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">双字节<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=249>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">0～65535<O:P></O:P></SPAN></P></TD></TR>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=189>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">signed
int<O:P></O:P></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">双字节<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=249>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">-32768～+32767<O:P></O:P></SPAN></P></TD></TR>
<TR>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 142.1pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=189>
<P class=MsoNormal><SPAN lang=EN-US
style="FONT-FAMILY: 宋体">unsigned
long<O:P></O:P></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 97.3pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
vAlign=top width=130>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体">四字节<SPAN
lang=EN-US><O:P></O:P></SPAN></SPAN></P></TD>
<TD
style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 187pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt"
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -