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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!-- but may not be published or retransmitted without explicit permission.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 21:47:46 2005 by faqproc version 2.7 --><!-- from source file lib1.sgml dated Sat Feb 7 18:46:53 2004 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/lib/itoa.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:58 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 13.1</title><link href="../stdio/runtimesc2.html" rev=precedes><link href="strncpy.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="../stdio/runtimesc2.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="strncpy.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 13.1</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>How can I convert numbers to strings(the opposite of <TT>atoi</TT>)?Is there an <TT>itoa</TT> function?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>Just use <TT>sprintf</TT>:<pre> sprintf(string, "%d", number);</pre>(Don't worry that <TT>sprintf</TT> may be overkill,potentially wasting run time or code space;it works well in practice.)Seealsothe examples in the answer to question <a href="../malloc/retaggr.html">7.5a</a>,andalsoquestions<a href="../charstring/asciivals.html">8.6</a>and<a href="../stdio/sprintfsize.html">12.21</a>.</p><p>You can obviously use <TT>sprintf</TT> to convertlongor floating-point numbers to strings as well(using <TT>%ld</TT> or <TT>%f)</TT>;in other words,<TT>sprintf</TT>can also be thought of asthe opposite of<TT>atol</TT>and <TT>atof</TT>.In addition,you have quite a bit of control over the formatting.(It'sfor these reasonsthatC supplies <TT>sprintf</TT> as a general solution,and not <TT>itoa</TT>.)</p><p>If you simply must write an <TT>itoa</TT> function,here are some things to consider:<UL><li>There is asample implementation in K&R.<li>You'll have to worry aboutreturn buffer allocation;see question <a href="../malloc/retaggr.html">7.5a</a>.<li>A naïve implementation usuallydoesn'thandle the most-negative integer(INT_MIN, usually -32,768 or -2,147,483,648)properly.</UL></p><p>See also questions <a href="../stdio/sprintfsize.html">12.21</a> and <a href="../misc/hexio.html">20.10</a>.</p><p>References:K&R1 Sec. 3.6 p. 60<br>K&R2 Sec. 3.6 p. 64<br></p><!-- aend --><p><hr><a href="../stdio/runtimesc2.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="strncpy.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/lib/itoa.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:58 GMT --></html>⌨️ 快捷键说明
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