152 lines
5.5 KiB
HTML
152 lines
5.5 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>malloc</title>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="malloc"></a> <a name="tag_03_357"></a><!-- malloc -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_357_01"></a>NAME</h4>
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<blockquote>malloc - a memory allocator</blockquote>
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<h4><a name="tag_03_357_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/stdlib.h.html">stdlib.h</a>><br>
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<br>
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void *malloc(size_t</tt> <i>size</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_357_03"></a>DESCRIPTION</h4>
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<blockquote>
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<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
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border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
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requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
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the ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
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<p>The <i>malloc</i>() function shall allocate unused space for an object whose size in bytes is specified by <i>size</i> and whose
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value is unspecified.</p>
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<p>The order and contiguity of storage allocated by successive calls to <i>malloc</i>() is unspecified. The pointer returned if the
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allocation succeeds shall be suitably aligned so that it may be assigned to a pointer to any type of object and then used to access
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such an object in the space allocated (until the space is explicitly freed or reallocated). Each such allocation shall yield a
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pointer to an object disjoint from any other object. The pointer returned points to the start (lowest byte address) of the
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allocated space. If the space cannot be allocated, a null pointer shall be returned. If the size of the space requested is 0, the
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behavior is implementation-defined: the value returned shall be either a null pointer or a unique pointer.</p>
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</blockquote>
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<h4><a name="tag_03_357_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion with <i>size</i> not equal to 0, <i>malloc</i>() shall return a pointer to the allocated space. If
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<i>size</i> is 0, either a null pointer or a unique pointer that can be successfully passed to <a href=
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"../functions/free.html"><i>free</i>()</a> shall be returned. Otherwise, it shall return a null pointer <sup>[<a href=
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"javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> and set
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<i>errno</i> to indicate the error. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_357_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>malloc</i>() function shall fail if:</p>
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<dl compact>
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<dt>[ENOMEM]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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Insufficient storage space is available. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_357_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_357_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_357_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_357_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_357_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="calloc.html"><i>calloc</i>()</a> , <a href="free.html"><i>free</i>()</a> , <a href="realloc.html"><i>realloc</i>()</a>
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, the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/stdlib.h.html"><i><stdlib.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_357_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_357_12"></a>Issue 6</h4>
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<blockquote>
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<p>Extensions beyond the ISO C standard are marked.</p>
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<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
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<ul>
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<li>
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<p>In the RETURN VALUE section, the requirement to set <i>errno</i> to indicate an error is added.</p>
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</li>
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<li>
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<p>The [ENOMEM] error condition is added.</p>
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</li>
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</ul>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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