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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>calloc</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="calloc"></a> <a name="tag_03_48"></a><!-- calloc --> <!--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_48_01"></a>NAME</h4><blockquote>calloc - a memory allocator</blockquote><h4><a name="tag_03_48_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/stdlib.h.html">stdlib.h</a>><br><br> void *calloc(size_t</tt> <i>nelem</i><tt>, size_t</tt> <i>elsize</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_48_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>calloc</i>() function shall allocate unused space for an array of <i>nelem</i> elements each of whose size in bytes is<i>elsize</i>. The space shall be initialized to all bits 0.</p><p>The order and contiguity of storage allocated by successive calls to <i>calloc</i>() is unspecified. The pointer returned if theallocation succeeds shall be suitably aligned so that it may be assigned to a pointer to any type of object and then used to accesssuch an object or an array of such objects in the space allocated (until the space is explicitly freed or reallocated). Each suchallocation shall yield a pointer to an object disjoint from any other object. The pointer returned shall point to the start (lowestbyte address) of the allocated space. If the space cannot be allocated, a null pointer shall be returned. If the size of the spacerequested is 0, the behavior is implementation-defined: the value returned shall be either a null pointer or a unique pointer.</p></blockquote><h4><a name="tag_03_48_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion with both <i>nelem</i> and <i>elsize</i> non-zero, <i>calloc</i>() shall return a pointer to theallocated space. If either <i>nelem</i> or <i>elsize</i> is 0, then either a null pointer or a unique pointer value that can besuccessfully passed to <a href="../functions/free.html"><i>free</i>()</a> shall be returned. Otherwise, it shall return a nullpointer <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> and set <i>errno</i> to indicate the error. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p></blockquote><h4><a name="tag_03_48_05"></a>ERRORS</h4><blockquote><p>The <i>calloc</i>() function shall fail if:</p><dl compact><dt>[ENOMEM]</dt><dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Insufficient memory is available. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_48_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_48_07"></a>APPLICATION USAGE</h4><blockquote><p>There is now no requirement for the implementation to support the inclusion of <i><malloc.h></i>.</p></blockquote><h4><a name="tag_03_48_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_48_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_48_10"></a>SEE ALSO</h4><blockquote><p><a href="free.html"><i>free</i>()</a> , <a href="malloc.html"><i>malloc</i>()</a> , <a href="realloc.html"><i>realloc</i>()</a>, the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdlib.h.html"><i><stdlib.h></i></a></p></blockquote><h4><a name="tag_03_48_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_48_12"></a>Issue 6</h4><blockquote><p>Extensions beyond the ISO C standard are marked.<br></p><p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p><ul><li><p>The setting of <i>errno</i> and the [ENOMEM] error condition are mandatory if an insufficient memory condition occurs.</p></li></ul></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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