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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN"><!-- This collection of hypertext pages is Copyright 1995-2005 by Steve Summit. --><!-- Content from the book "C Programming FAQs: Frequently Asked Questions" --><!-- (Addison-Wesley, 1995, ISBN 0-201-84519-9) is made available here by --><!-- permission of the author and the publisher as a service to the community. --><!-- It is intended to complement the use of the published text --><!-- and is protected by international copyright laws. --><!-- The on-line content may be accessed freely for personal use --><!-- but may not be published or retransmitted without explicit permission. --><!-- --><!-- this page built Sat Dec 24 21:47:45 2005 by faqproc version 2.7 --><!-- from source file aryptr.sgml dated Wed Dec 21 12:50:38 2005 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/aryptr/fn33.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 08:00:00 GMT --><head><meta name=GENERATOR content="faqproc"><link href="aryptr/dynmuldimary.html" rev=subdocument><title>Footnote</title></head><body bgcolor="#ffffff"> <a href="../index-2.html"><img src="../images/buttontop.gif" alt="top/contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><hr>Any time you're allocating space for a pointer <TT>p</TT> to point to,it can be a good idea to use the idiom<pre> p = malloc(n * sizeof(*p));</pre>rather than the more obvious<pre> p = malloc(n * sizeof(int));</pre>(where of course the type we need the size of isn't necessarily <TT>int</TT>,but rather whatever type it is that <TT>p</TT> points to<a href="fn34.html" rel=subdocument>[footnote]</a>).The reason is that the code is more self-contained,more self-documenting,and more robust:a reader looking at<pre> p = malloc(n * sizeof(*p));</pre>can see immediately that the correct amount of space is being allocated,without looking back at <TT>p</TT>'s declaration to see what type it is.If <TT>p</TT>'s type ever changes,the <TT>malloc</TT> call may not have to change.<br><br>The <TT>sizeof(p)</TT> form can also be seenin the <TT>array4</TT> and <TT>array5</TT> examples.<hr><p><a href="dynmuldimary.html" rev=subdocument>back</a></p><hr><p><a href="../questions.html"><img src="../images/buttontop.gif" alt="contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><br><a href="../about.html">about this FAQ list</a> <a href="../eskimo.html">about eskimo</a> <a href="../search.html">search</a> <a href="../feedback.html">feedback</a> <a href="copyright.html">copyright</a><p>Hosted by<a href="http://www.eskimo.com/"><img src="../../www.eskimo.com/img/link/eskitiny.gif" alt="Eskimo North"></a></p></body><!-- Mirrored from c-faq.com/aryptr/fn33.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 08:00:01 GMT --></html>⌨️ 快捷键说明
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