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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>pthread_setspecific</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><a name = "tag_000_007_1714"> </a>NAME</h4><blockquote>pthread_setspecific, pthread_getspecific - thread-specific data management</blockquote><h4><a name = "tag_000_007_1715"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="pthread.h.html">pthread.h</a>>int pthread_setspecific(pthread_key_t <i>key</i>, const void *<i>value</i>);void *pthread_getspecific(pthread_key_t <i>key</i>);</code></pre></blockquote><h4><a name = "tag_000_007_1716"> </a>DESCRIPTION</h4><blockquote>The<i>pthread_setspecific()</i>function associates a thread-specific<i>value</i>with a<i>key</i>obtained via a previous call to<i><a href="pthread_key_create.html">pthread_key_create()</a></i>.Different threads may bind different values to the same key.These values are typically pointers to blocks of dynamically allocated memorythat have been reserved for use by the calling thread.<p>The<i>pthread_getspecific()</i>function returns the value currently bound to the specified<i>key</i>on behalf of the calling thread.<p>The effect of calling<i>pthread_setspecific()</i>or<i>pthread_getspecific()</i>with a<i>key</i>value not obtained from<i><a href="pthread_key_create.html">pthread_key_create()</a></i>or after<i>key</i>has been deleted with<i><a href="pthread_key_delete.html">pthread_key_delete()</a></i>is undefined.<p>Both<i>pthread_setspecific()</i>and<i>pthread_getspecific()</i>may be called from a thread-specific data destructor function.However, calling<i>pthread_setspecific()</i>from a destructor may result in lost storage or infinite loops.<p>Both functions may be implemented as macros.</blockquote><h4><a name = "tag_000_007_1717"> </a>RETURN VALUE</h4><blockquote>The function<i>pthread_getspecific()</i>returns the thread-specific data valueassociated with the given<i>key</i>.If no thread-specific data value is associated with<i>key</i>,then the value NULL is returned.<p>If successful, the<i>pthread_setspecific()</i>function returns zero.Otherwise, an error number is returned to indicate the error.</blockquote><h4><a name = "tag_000_007_1718"> </a>ERRORS</h4><blockquote>The <i>pthread_setspecific()</i>function will fail if:<dl compact><dt>[ENOMEM]<dd>Insufficient memory exists to associate the value with the key.</dl><p>The<i>pthread_setspecific()</i>function may fail if:<dl compact><dt>[EINVAL]<dd>The key value is invalid.</dl><p>No errors are returned from<i>pthread_getspecific()</i>.<p>These functions will not return an error code of [EINTR].</blockquote><h4><a name = "tag_000_007_1719"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1720"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1721"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_1722"> </a>SEE ALSO</h4><blockquote><i><a href="pthread_key_create.html">pthread_key_create()</a></i>,<i><a href="pthread.h.html"><pthread.h></a></i>.<br></blockquote><h4>DERIVATION</h4><blockquote>Derived from the POSIX Threads Extension (1003.1c-1995)</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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