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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!-- but may not be published or retransmitted without explicit permission.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 21:47:47 2005 by faqproc version 2.7 --><!-- from source file misctechn.sgml dated Sat Sep 28 22:23:36 2002 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/misc/multretval.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:04 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 20.1</title><link href="../osdep/sysdep.html" rev=precedes><link href="ragged.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="../osdep/sysdep.html" rev=precedes><img src="../images/buttonleft.gif" alt="prev"></a><a href="index.html" rev=subdocument><img src="../images/buttonup.gif" alt="up"></a><a href="ragged.html" rel=precedes><img src="../images/buttonright.gif" alt="next"></a> <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><p><!-- qbegin --><h1>comp.lang.c FAQ list<font color=blue>·</font><!-- qtag -->Question 20.1</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>How can I returnmultiplevalues from a function?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>There are several ways of doing this.(These examples show hypotheticalpolar-to-rectangular coordinate conversion functions,which must return both an <TT>x</TT> and a <TT>y</TT> coordinate.)</p><OL><li>Passpointers toseverallocations which the function can fill in:<pre>#include <math.h>polar_to_rectangular(double rho, double theta, double *xp, double *yp){ *xp = rho * cos(theta); *yp = rho * sin(theta);}... double x, y; polar_to_rectangular(1., 3.14, &x, &y);</pre><li>Havethe function return a structurecontaining the desired values:<pre>struct xycoord { double x, y; };struct xycoordpolar_to_rectangular(double rho, double theta){ struct xycoord ret; ret.x = rho * cos(theta); ret.y = rho * sin(theta); return ret;}... struct xycoord c = polar_to_rectangular(1., 3.14);</pre><li>Use a hybrid:have the function accept a pointer to a structure,which it fills in:<pre>polar_to_rectangular(double rho, double theta, struct xycoord *cp){ cp->x = rho * cos(theta); cp->y = rho * sin(theta);}... struct xycoord c; polar_to_rectangular(1., 3.14, &c);</pre>(Another example of this technique is the Unix system call <TT>stat</TT>.)<li>In a pinch,you could theoretically useglobal variables(though this is rarelya good idea).</OL><p>See alsoquestions <a href="../struct/firstclass.html">2.7</a>, <a href="../ptrs/passptrinit.html">4.8</a>, and <a href="../malloc/retaggr.html">7.5a</a>.</p><!-- aend --><p><hr><a href="../osdep/sysdep.html" rev=precedes><img src="../images/buttonleft.gif" alt="prev"></a><a href="index.html" rev=subdocument><img src="../images/buttonup.gif" alt="up"></a><a href="ragged.html" rel=precedes><img src="../images/buttonright.gif" alt="next"></a> <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><!-- lastfooter --><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></body><!-- Mirrored from c-faq.com/misc/multretval.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:04 GMT --></html>⌨️ 快捷键说明
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