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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!-- but may not be published or retransmitted without explicit permission.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 varargs.sgml dated Sun Nov 25 08:09:42 2001 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/varargs/oldvarargs.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:00 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 15.7</title><link href="vscanf.html" rev=precedes><link href="nargs.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="vscanf.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="nargs.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 15.7</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>I havea pre-ANSIcompiler,without <TT><stdarg.h></TT>.What can I do?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>There's an older header, <TT><varargs.h></TT>,which offers about the same functionality.</p><p>Here isthe <TT>vstrcat</TT> function from question <a href="varargs1.html">15.4</a>,rewritten to use <TT><varargs.h></TT>:<pre>#include <stdio.h>#include <varargs.h>#include <string.h>extern char *malloc();char *vstrcat(va_alist)va_dcl /* no semicolon */{ int len = 0; char *retbuf; va_list argp; char *p; va_start(argp); while((p = va_arg(argp, char *)) != NULL) /* includes first */ len += strlen(p); va_end(argp); retbuf = malloc(len + 1); /* +1 for trailing \0 */ if(retbuf == NULL) return NULL; /* error */ retbuf[0] = '\0'; va_start(argp); /* restart for second scan */ while((p = va_arg(argp, char *)) != NULL) /* includes first */ strcat(retbuf, p); va_end(argp); return retbuf;}</pre>(Notethat there is no semicolon after <TT>va_dcl</TT>.Note that in this case,no special treatment for the first argument is necessary.)You may also have todeclare the string functions by handrather than using <TT><string.h></TT>.</p><p>If you can manage to find a system with <TT>vfprintf</TT>but without <TT><stdarg.h></TT>,here is a version of the <TT>error</TT> function(from question <a href="vprintf.html">15.5</a>)using <TT><varargs.h></TT>:<pre>#include <stdio.h>#include <varargs.h>void error(va_alist)va_dcl /* no semicolon */ { char *fmt; va_list argp; fprintf(stderr, "error: "); va_start(argp); fmt = va_arg(argp, char *); vfprintf(stderr, fmt, argp); va_end(argp); fprintf(stderr, "\n");}</pre>(Notethatin contrast to <TT><stdarg.h></TT>,under <TT><varargs.h></TT> <em>all</em> arguments are variable,sothe <TT>fmt</TT> argument must also be picked up via <TT>va_arg</TT>.)</p><p>References:H&S Sec. 11.4 pp. 296-9<br>CT&P Sec. A.2 pp. 134-139<br>PCS Sec. 11 pp. 184-5, Sec. 13 p. 250<br></p><!-- aend --><p><hr><a href="vscanf.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="nargs.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/varargs/oldvarargs.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:00 GMT --></html>⌨️ 快捷键说明
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