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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>endhostent</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4>NAME</h4><blockquote>endhostent, gethostbyaddr, gethostbyname, gethostent, sethostent - network host database functions</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="netdb.h.html">netdb.h</a>>extern int h_errno;void endhostent(void);struct hostent *gethostbyaddr(const void *<I>addr</I>, size_t <I>len</I>, int <I>type</I>);struct hostent *gethostbyname(const char *<I>name</I>);struct hostent *gethostent(void);void sethostent(int <I>stayopen</I>);</code></pre></blockquote><h4>DESCRIPTION</h4><blockquote>The<i>gethostent()</i>,<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>,and<i>gethostbyname()</i>functions each return a pointer to a <B>hostent</B> structure, the members ofwhich contain the fields of an entry in the network host database.<p>The<i>gethostent()</i>function reads the next entry of the database, opening a connection to thedatabase if necessary.<p>The<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>function searches the database and finds an entrywhich matches the address family specified by the<I>type</I>argument and which matches theaddress pointed to by the<I>addr</I>argument, opening a connection to the database if necessary. The<I>addr</I> argument is a pointer to the binary-format (that is, notnull-terminated) address in network byte order, whose length is specified bythe <I>len</I> argument. The datatype of the address depends on the addressfamily. For an address of type AF_INET, this is an <B>in_addr</B>structure, defined in<i><a href="netinetin.h.html"><netinet/in.h></a></i>.<p>The<i>gethostbyname()</i>function searches the database and finds an entrywhich matches the host name specified by the<I>name</I>argument, opening a connection to the database if necessary.If <I>name</I>is an alias for a valid host name, the function returns information about the host name to which the aliasrefers, and <I>name</I>is included in the list of aliases returned.<p>The<i><a href="sethostent.html">sethostent()</a></i>function opens a connection to the network host database, and sets theposition of the next entry to the first entry. If the <I>stayopen</I> argumentis non-zero, the connection to the host database will not be closed after eachcall to<i>gethostent()</i>(either directly, or indirectly through one of the other<i>gethost*()</i>functions).<p>The<i>endhostent()</i>function closes the connection to the database.</blockquote><h4>RETURN VALUE</h4><blockquote>On successful completion,<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>,<i>gethostbyname()</i>and<i>gethostent()</i>return a pointer to a <B>hostent</B> structure if the requested entry wasfound, and a null pointer if the end of the database was reached or therequested entry was not found. Otherwise, a null pointer is returned.<p>On unsuccessful completion,<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>and<i>gethostbyname()</i>functions set <I>h_errno</I> to indicate the error.</blockquote><h4>ERRORS</h4><blockquote>No errors are defined for<i>endhostent()</i>,<i>gethostent()</i>and<i><a href="sethostent.html">sethostent()</a></i>.<p>The<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>and<i>gethostbyname()</i>functions will fail in the following cases, setting<I>h_errno</I>to the value shown in the list below. Any changes to<I>errno</I>are unspecified.<dl compact><dt>[HOST_NOT_FOUND]<dd><br>No such host is known.<dt>[NO_DATA]<dd>The server recognised the request and the name but no address is available.Another type of request to the name server for the domain might return ananswer.<dt>[NO_RECOVERY]<dd>An unexpected server failure occurred which can not be recovered.<dt>[TRY_AGAIN]<dd>A temporary and possibly transienterror occurred, such as a failure of a server to respond.</dl></blockquote><h4>APPLICATION USAGE</h4><blockquote>The<i>gethostent()</i>,<i><a href="gethostbyaddr.html">gethostbyaddr()</a></i>,and<i>gethostbyname()</i>functions may return pointers to static data, which may be overwritten bysubsequent calls to any of these functions.<p>These functions are generally used with the Internet address family.</blockquote><h4>SEE ALSO</h4><blockquote><i><a href="endservent.html">endservent()</a></i>,<i><a href="htonl.html">htonl()</a></i>,<i><a href="inet_addr.html">inet_addr()</a></i>,<i><a href="netdb.h.html"><netdb.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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