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<html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><title>[ 永远的UNIX > C语言库函数(U类字母) ]</title><style type="text/css"><!--body,th,input,select,textarea,select,checkbox{font:12pt 宋体}A:link { text-decoration:underline; color:#E6A306}A:visited { text-decoration:underline; color:#E6A306}A:hover { text-decoration:underline; color:#FFFF00}body {  font-family: "宋体", "serif"; font-size: 12pt}td {  font-family: "宋体", "serif"; font-size: 12pt}p  { font-size: 9pt; line-height: 150%}--></style></head><body text="#ffffff" background="/images/bline.gif" bgcolor="#000000"><div align="center"><center><table border="0" width="750"  cellspacing="0" cellpadding="0" height="400"><tr>  <td height="45"><p align="center"><img src="/images/title.gif" alt="[ 永远的UNIX::UNIX技术资料的宝库 ]"></td>  </tr> <tr><tr> <td align=left height="40" valign=bottom align=left><small><a href="/">首页</a> > 编程技术 > C/C++ >   正文</small></td></tr><tr>  <td width="100%" height="2" colspan="5" bgcolor="#D09F0D"><img src="/images/c.gif" width=1 height=1></td> </tr><tr> <td align=center height="40" valign=middle><font size=5><b>C语言库函数(U类字母)</b></font></td></tr><tr> <td align=center height="20"><font color=#999999><small>本文出自: 作者: (2001-10-27 08:05:01)</small></font></td></tr><td align=center><table border="0" width="700"  cellspacing="0" cellpadding="0" align=center><tr><td valign=top><font color=#cccccc>　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<br>函数名:&nbsp;ultoa&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;转换一个无符号长整型数为字符串&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;char&nbsp;*ultoa(unsigned&nbsp;long&nbsp;value,&nbsp;char&nbsp;*string,&nbsp;int&nbsp;radix);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;stdlib.h&gt;&nbsp;
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>
<br>int&nbsp;main(&nbsp;void&nbsp;)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;unsigned&nbsp;long&nbsp;lnumber&nbsp;=&nbsp;3123456789L;&nbsp;
<br>&nbsp;&nbsp;&nbsp;char&nbsp;string[25];&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;ultoa(lnumber,string,10);&nbsp;
<br>&nbsp;&nbsp;&nbsp;printf("string&nbsp;=&nbsp;%s&nbsp;&nbsp;unsigned&nbsp;long&nbsp;=&nbsp;%lu\n",string,lnumber);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>函数名:&nbsp;ungetc&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;把一个字符退回到输入流中&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;int&nbsp;ungetc(char&nbsp;c,&nbsp;FILE&nbsp;*stream);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>#include&nbsp;&lt;ctype.h&gt;&nbsp;
<br>
<br>int&nbsp;main(&nbsp;void&nbsp;)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;int&nbsp;i=0;&nbsp;
<br>&nbsp;&nbsp;&nbsp;char&nbsp;ch;&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;puts("Input&nbsp;an&nbsp;integer&nbsp;followed&nbsp;by&nbsp;a&nbsp;char:");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;/*&nbsp;read&nbsp;chars&nbsp;until&nbsp;non&nbsp;digit&nbsp;or&nbsp;EOF&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;while((ch&nbsp;=&nbsp;getchar())&nbsp;!=&nbsp;EOF&nbsp;&&&nbsp;isdigit(ch))&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;i&nbsp;=&nbsp;10&nbsp;*&nbsp;i&nbsp;+&nbsp;ch&nbsp;-&nbsp;48;&nbsp;/*&nbsp;convert&nbsp;ASCII&nbsp;into&nbsp;int&nbsp;value&nbsp;*/&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;/*&nbsp;if&nbsp;non&nbsp;digit&nbsp;char&nbsp;was&nbsp;read,&nbsp;push&nbsp;it&nbsp;back&nbsp;into&nbsp;input&nbsp;buffer&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(ch&nbsp;!=&nbsp;EOF)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ungetc(ch,&nbsp;stdin);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;printf("i&nbsp;=&nbsp;%d,&nbsp;next&nbsp;char&nbsp;in&nbsp;buffer&nbsp;=&nbsp;%c\n",&nbsp;i,&nbsp;getchar());&nbsp;
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>函数名:&nbsp;ungetch&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;把一个字符退回到键盘缓冲区中&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;int&nbsp;ungetch(int&nbsp;c);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>#include&nbsp;&lt;ctype.h&gt;&nbsp;
<br>#include&nbsp;&lt;conio.h&gt;&nbsp;
<br>
<br>int&nbsp;main(&nbsp;void&nbsp;)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;int&nbsp;i=0;&nbsp;
<br>&nbsp;&nbsp;&nbsp;char&nbsp;ch;&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;puts("Input&nbsp;an&nbsp;integer&nbsp;followed&nbsp;by&nbsp;a&nbsp;char:");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;/*&nbsp;read&nbsp;chars&nbsp;until&nbsp;non&nbsp;digit&nbsp;or&nbsp;EOF&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;while((ch&nbsp;=&nbsp;getche())&nbsp;!=&nbsp;EOF&nbsp;&&&nbsp;isdigit(ch))&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;i&nbsp;=&nbsp;10&nbsp;*&nbsp;i&nbsp;+&nbsp;ch&nbsp;-&nbsp;48;&nbsp;/*&nbsp;convert&nbsp;ASCII&nbsp;into&nbsp;int&nbsp;value&nbsp;*/&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;/*&nbsp;if&nbsp;non&nbsp;digit&nbsp;char&nbsp;was&nbsp;read,&nbsp;push&nbsp;it&nbsp;back&nbsp;into&nbsp;input&nbsp;buffer&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(ch&nbsp;!=&nbsp;EOF)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ungetch(ch);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;printf("\n\ni&nbsp;=&nbsp;%d,&nbsp;next&nbsp;char&nbsp;in&nbsp;buffer&nbsp;=&nbsp;%c\n",&nbsp;i,&nbsp;getch());&nbsp;
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>函数名:&nbsp;unixtodos&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;把日期和时间转换成DOS格式&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;void&nbsp;unixtodos(long&nbsp;utime,&nbsp;struct&nbsp;date&nbsp;*dateptr,&nbsp;
<br>&nbsp;&nbsp;&nbsp;struct&nbsp;time&nbsp;*timeptr);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>#include&nbsp;&lt;dos.h&gt;&nbsp;
<br>
<br>char&nbsp;*month[]&nbsp;=&nbsp;{"---",&nbsp;"Jan",&nbsp;"Feb",&nbsp;"Mar",&nbsp;"Apr",&nbsp;"May",&nbsp;"Jun",&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;"Jul",&nbsp;"Aug",&nbsp;"Sep",&nbsp;"Oct",&nbsp;"Nov",&nbsp;"Dec"};&nbsp;
<br>
<br>#define&nbsp;SECONDS_PER_DAY&nbsp;86400L&nbsp;&nbsp;/*&nbsp;the&nbsp;number&nbsp;of&nbsp;seconds&nbsp;in&nbsp;one&nbsp;day&nbsp;*/&nbsp;
<br>
<br>struct&nbsp;date&nbsp;dt;&nbsp;
<br>struct&nbsp;time&nbsp;tm;&nbsp;
<br>
<br>int&nbsp;main(void)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;unsigned&nbsp;long&nbsp;val;&nbsp;
<br>
<br>/*&nbsp;get&nbsp;today's&nbsp;date&nbsp;and&nbsp;time&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;getdate(&dt);&nbsp;
<br>&nbsp;&nbsp;&nbsp;gettime(&tm);&nbsp;
<br>&nbsp;&nbsp;&nbsp;printf("today&nbsp;is&nbsp;%d&nbsp;%s&nbsp;%d\n",&nbsp;dt.da_day,&nbsp;month[dt.da_mon],&nbsp;dt.da_year);&nbsp;
<br>
<br>/*&nbsp;convert&nbsp;date&nbsp;and&nbsp;time&nbsp;to&nbsp;unix&nbsp;format&nbsp;(number&nbsp;of&nbsp;seconds&nbsp;since&nbsp;Jan&nbsp;1,&nbsp;1970&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;val&nbsp;=&nbsp;dostounix(&dt,&nbsp;&tm);&nbsp;
<br>/*&nbsp;subtract&nbsp;42&nbsp;days&nbsp;worth&nbsp;of&nbsp;seconds&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;val&nbsp;-=&nbsp;(SECONDS_PER_DAY&nbsp;*&nbsp;42);&nbsp;
<br>
<br>/*&nbsp;convert&nbsp;back&nbsp;to&nbsp;dos&nbsp;time&nbsp;and&nbsp;date&nbsp;*/&nbsp;
<br>&nbsp;&nbsp;&nbsp;unixtodos(val,&nbsp;&dt,&nbsp;&tm);&nbsp;
<br>&nbsp;&nbsp;&nbsp;printf("42&nbsp;days&nbsp;ago&nbsp;it&nbsp;was&nbsp;%d&nbsp;%s&nbsp;%d\n",&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dt.da_day,&nbsp;month[dt.da_mon],&nbsp;dt.da_year);&nbsp;
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>函数名:&nbsp;unlink&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;删掉一个文件&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;int&nbsp;unlink(char&nbsp;*filename);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>#include&nbsp;&lt;io.h&gt;&nbsp;
<br>
<br>int&nbsp;main(void)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;FILE&nbsp;*fp&nbsp;=&nbsp;fopen("junk.jnk","w");&nbsp;
<br>&nbsp;&nbsp;&nbsp;int&nbsp;status;&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;fprintf(fp,"junk");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;status&nbsp;=&nbsp;access("junk.jnk",0);&nbsp;
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(status&nbsp;==&nbsp;0)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("File&nbsp;exists\n");&nbsp;
<br>&nbsp;&nbsp;&nbsp;else&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("File&nbsp;doesn't&nbsp;exist\n");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;fclose(fp);&nbsp;
<br>&nbsp;&nbsp;&nbsp;unlink("junk.jnk");&nbsp;
<br>&nbsp;&nbsp;&nbsp;status&nbsp;=&nbsp;access("junk.jnk",0);&nbsp;
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(status&nbsp;==&nbsp;0)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("File&nbsp;exists\n");&nbsp;
<br>&nbsp;&nbsp;&nbsp;else&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("File&nbsp;doesn't&nbsp;exist\n");&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>&nbsp;&nbsp;
<br>
<br>函数名:&nbsp;unlock&nbsp;
<br>功&nbsp;&nbsp;能:&nbsp;解除文件共享锁&nbsp;
<br>用&nbsp;&nbsp;法:&nbsp;int&nbsp;unlock(int&nbsp;handle,&nbsp;long&nbsp;offset,&nbsp;long&nbsp;length);&nbsp;
<br>程序例:&nbsp;
<br>
<br>#include&nbsp;&lt;io.h&gt;&nbsp;
<br>#include&nbsp;&lt;fcntl.h&gt;&nbsp;
<br>#include&nbsp;&lt;sys\stat.h&gt;&nbsp;
<br>#include&nbsp;&lt;process.h&gt;&nbsp;
<br>#include&nbsp;&lt;share.h&gt;&nbsp;
<br>#include&nbsp;&lt;stdio.h&gt;&nbsp;
<br>
<br>int&nbsp;main(void)&nbsp;
<br>{&nbsp;
<br>&nbsp;&nbsp;&nbsp;int&nbsp;handle,&nbsp;status;&nbsp;
<br>&nbsp;&nbsp;&nbsp;long&nbsp;length;&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;handle&nbsp;=&nbsp;sopen("c:\\autoexec.bat",O_RDONLY,SH_DENYNO,S_IREAD);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(handle&nbsp;&lt;&nbsp;0)&nbsp;
<br>&nbsp;&nbsp;&nbsp;{&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("sopen&nbsp;failed\n");&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;exit(1);&nbsp;
<br>&nbsp;&nbsp;&nbsp;}&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;length&nbsp;=&nbsp;filelength(handle);&nbsp;
<br>&nbsp;&nbsp;&nbsp;status&nbsp;=&nbsp;lock(handle,0L,length/2);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(status&nbsp;==&nbsp;0)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("lock&nbsp;succeeded\n");&nbsp;
<br>&nbsp;&nbsp;&nbsp;else&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("lock&nbsp;failed\n");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;status&nbsp;=&nbsp;unlock(handle,0L,length/2);&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;if&nbsp;(status&nbsp;==&nbsp;0)&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("unlock&nbsp;succeeded\n");&nbsp;
<br>&nbsp;&nbsp;&nbsp;else&nbsp;
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf("unlock&nbsp;failed\n");&nbsp;
<br>
<br>&nbsp;&nbsp;&nbsp;close(handle);&nbsp;
<br>&nbsp;&nbsp;&nbsp;return&nbsp;0;&nbsp;
<br>}&nbsp;
<br>(<a href=http://www.fanqiang.com>http://www.fanqiang.com</a>)</font>&nbsp;&nbsp;&nbsp;&nbsp;进入【<a href=http://www.chinaunix.net>UNIX论坛</a>】</td></tr><tr><td><hr></td></tr><tr><td><b>相关文章</b> </td></tr><tr><td><a href=/a4/b2/20011027/1305001515.html>C语言库函数(W类字母)</a> <small>(2001-10-27 13:05:00)</small></font><br><a href=/a4/b2/20011027/0905001514.html>C语言库函数(V类字母)</a> <small>(2001-10-27 09:05:00)</small></font><br><a href=/a4/b2/20011027/0805011513.html>C语言库函数(U类字母)</a> <small>(2001-10-27 08:05:01)</small></font><br><a href=/a4/b2/20011027/0705001512.html>C语言库函数(T类字母)</a> <small>(2001-10-27 07:05:00)</small></font><br><a href=/a4/b2/20011026/0900001511.html>C语言库函数(S类字母) - 3</a> <small>(2001-10-26 09:00:00)</small></font><br><a href=/a4/b2/20011026/0800011510.html>C语言库函数(S类字母) - 2</a> <small>(2001-10-26 08:00:01)</small></font><br><a href=/a4/b2/20011026/0700001509.html>C语言库函数(S类字母) - 1</a> <small>(2001-10-26 07:00:00)</small></font><br><a href=/a4/b2/20011025/0900011508.html>C语言库函数(R类字母)</a> <small>(2001-10-25 09:00:01)</small></font><br><a href=/a4/b2/20011025/0800031507.html>C语言库函数(Q类字母)</a> <small>(2001-10-25 08:00:03)</small></font><br><a href=/a4/b2/20011025/0700011506.html>C语言库函数(P类字母)</a> <small>(2001-10-25 07:00:01)</small></font><br></td></tr><tr><tr><td><br>===<a href=/cgi-bin/find.cgi?key=C语言库函数>更多相关</a>===</td></tr><td>&nbsp;</td></tr></table></td></tr><tr>  <td width="100%" height="2" colspan="5" bgcolor="#D09F0D"><img src="/images/c.gif" width=1 height=1></td> </tr><tr>    <td width="100%" height="40" colspan="5" valign=top><p align="center"><font color=#ffffff>★&nbsp;&nbsp;樊强制作 欢迎分享&nbsp;&nbsp;★ </font></p></td>  </tr></table></center></div></body></html>

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