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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>perror</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="perror"></a> <a name="tag_03_417"></a><!-- perror --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_417_01"></a>NAME</h4><blockquote>perror - write error messages to standard error</blockquote><h4><a name="tag_03_417_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/stdio.h.html">stdio.h</a>><br><br> void perror(const char *</tt><i>s</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_417_03"></a>DESCRIPTION</h4><blockquote><div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between therequirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers tothe ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div><p>The <i>perror</i>() function shall map the error number accessed through the symbol <i>errno</i> to a language-dependent errormessage, which shall be written to the standard error stream as follows:</p><ul><li><p>First (if <i>s</i> is not a null pointer and the character pointed to by <i>s</i> is not the null byte), the string pointed toby <i>s</i> followed by a colon and a <space>.</p></li><li><p>Then an error message string followed by a <newline>.</p></li></ul><p>The contents of the error message strings shall be the same as those returned by <a href="../functions/strerror.html"><i>strerror</i>()</a> with argument <i>errno</i>.</p><p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> The<i>perror</i>() function shall mark the file associated with the standard error stream as having been written (<i>st_ctime</i>,<i>st_mtime</i> marked for update) at some time between its successful completion and <a href="../functions/exit.html"><i>exit</i>()</a>, <a href="../functions/abort.html"><i>abort</i>()</a>, or the completion of <a href="../functions/fflush.html"><i>fflush</i>()</a> or <a href="../functions/fclose.html"><i>fclose</i>()</a> on <i>stderr</i>. <imgsrc="../images/opt-end.gif" alt="[Option End]" border="0"></p><p>The <i>perror</i>() function shall not change the orientation of the standard error stream.</p></blockquote><h4><a name="tag_03_417_04"></a>RETURN VALUE</h4><blockquote><p>The <i>perror</i>() function shall not return a value.</p></blockquote><h4><a name="tag_03_417_05"></a>ERRORS</h4><blockquote><p>No errors are defined.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_417_06"></a>EXAMPLES</h4><blockquote><h5><a name="tag_03_417_06_01"></a>Printing an Error Message for a Function</h5><p>The following example replaces <i>bufptr</i> with a buffer that is the necessary size. If an error occurs, the <i>perror</i>()function prints a message and the program exits.</p><pre><tt>#include <stdio.h>#include <stdlib.h>...char *bufptr;size_t szbuf;...if ((bufptr = malloc(szbuf)) == NULL) { perror("malloc"); exit(2);}...</tt></pre></blockquote><h4><a name="tag_03_417_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_417_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_417_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_417_10"></a>SEE ALSO</h4><blockquote><p><a href="strerror.html"><i>strerror</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a></p></blockquote><h4><a name="tag_03_417_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_417_12"></a>Issue 5</h4><blockquote><p>A paragraph is added to the DESCRIPTION indicating that <i>perror</i>() does not change the orientation of the standard errorstream.</p></blockquote><h4><a name="tag_03_417_13"></a>Issue 6</h4><blockquote><p>Extensions beyond the ISO C standard are marked.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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