c语言基础(07-c语言中的关键字).htm

语言基础(初学都必修)包括数据类型、运算符与表达式,运算符和表达式,逻辑运算符和逻辑表达式,C语言中的关键字,定义宏和使用宏定义,数据类型转换

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<P class=MsoNormal><SPAN style="COLOR: white; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">计算机响铃</SPAN><SPAN lang=EN-US style="COLOR: white"><o:p></o:p></SPAN></P></TD></TR>
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<P class=MsoNormal><SPAN style="COLOR: white; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">八进制常量（其中</SPAN><SPAN lang=EN-US style="COLOR: white">N</SPAN><SPAN style="COLOR: white; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是八进制常量）</SPAN><SPAN lang=EN-US style="COLOR: white"><o:p></o:p></SPAN></P></TD></TR>
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<P class=MsoNormal><SPAN style="COLOR: white; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">十六进制常量（其中</SPAN><SPAN lang=EN-US style="COLOR: white">N</SPAN><SPAN style="COLOR: white; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是十六进制常量）</SPAN><SPAN lang=EN-US style="COLOR: white"><o:p></o:p></SPAN></P></TD></TR></TBODY></TABLE>
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<P class=MsoNormal><SPAN style="COLOR: blue; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">各种数据类型的含义</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">――前面讲了有</SPAN><SPAN lang=EN-US>3</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">种基本的数据类型，它们分别是</SPAN><SPAN lang=EN-US>int, char, float </SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，实际上经常要用到的有</SPAN><SPAN lang=EN-US>5</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">种基本数据类型，还要加上</SPAN><SPAN lang=EN-US>2</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">种　</SPAN><SPAN lang=EN-US>void </SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN lang=EN-US>double.</SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">每一种数据类型决定了可以存放什么样的数以及在内存中占多少字节。</SPAN><SPAN lang=EN-US><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN-LEFT: 10.5pt; TEXT-INDENT: -10.5pt; mso-char-indent-count: -1.0; mso-char-indent-size: 10.5pt"><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（首先要讲一下字节是什么。字节是存储器的计量单位。在计算机中存储器最小的计量单位是</SPAN><SPAN lang=EN-US style="COLOR: #993300">bit</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（位），每</SPAN><SPAN lang=EN-US style="COLOR: #993300">1</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个</SPAN><SPAN lang=EN-US style="COLOR: #993300">bit</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对应一个二进制的一位，如有一个二进制数　</SPAN><SPAN lang=EN-US style="COLOR: #993300">1101</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，那么这一个二进制数有</SPAN><SPAN lang=EN-US style="COLOR: #993300">4</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位，在内存中要占</SPAN><SPAN lang=EN-US style="COLOR: #993300">4 bit</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN><SPAN lang=EN-US style="COLOR: #993300">1</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个字节有</SPAN><SPAN lang=EN-US style="COLOR: #993300">8bit</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（</SPAN><SPAN lang=EN-US style="COLOR: #993300">8</SPAN><SPAN style="COLOR: #993300; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位）。对于这些知识一定要熟记。）</SPAN><SPAN lang=EN-US style="COLOR: #993300"><o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US>&nbsp;</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">各种数据类型在内存中所占的长度：（一般就说数据类型的长度，这个长度也决定了取值范围）<BR></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">字符型　　</SPAN><SPAN lang=EN-US>char<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp; </SPAN>1</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个字节（</SPAN><SPAN lang=EN-US>8</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位）<BR></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family