1<html lang="en"> 2<head> 3<title>va_start - Untitled</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Untitled"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Stdarg.html#Stdarg" title="Stdarg"> 9<link rel="next" href="va_005farg.html#va_005farg" title="va_arg"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<meta http-equiv="Content-Style-Type" content="text/css"> 12<style type="text/css"><!-- 13 pre.display { font-family:inherit } 14 pre.format { font-family:inherit } 15 pre.smalldisplay { font-family:inherit; font-size:smaller } 16 pre.smallformat { font-family:inherit; font-size:smaller } 17 pre.smallexample { font-size:smaller } 18 pre.smalllisp { font-size:smaller } 19 span.sc { font-variant:small-caps } 20 span.roman { font-family:serif; font-weight:normal; } 21 span.sansserif { font-family:sans-serif; font-weight:normal; } 22--></style> 23<link rel="stylesheet" type="text/css" href="../cs.css"> 24</head> 25<body> 26<div class="node"> 27<a name="va_start"></a> 28<a name="va_005fstart"></a> 29<p> 30Next: <a rel="next" accesskey="n" href="va_005farg.html#va_005farg">va_arg</a>, 31Up: <a rel="up" accesskey="u" href="Stdarg.html#Stdarg">Stdarg</a> 32<hr> 33</div> 34 35<h4 class="subsection">13.1.1 Initialize variable argument list</h4> 36 37<p><a name="index-va_005fstart-497"></a><strong>Synopsis</strong> 38<pre class="example"> #include <stdarg.h> 39 void va_start(va_list <var>ap</var>, <var>rightmost</var>); 40</pre> 41 <p><strong>Description</strong><br> 42Use <code>va_start</code> to initialize the variable argument list <var>ap</var>, 43so that <code>va_arg</code> can extract values from it. <var>rightmost</var> is 44the name of the last explicit argument in the parameter list (the 45argument immediately preceding the ellipsis ‘<samp><span class="samp">...</span></samp>’ that flags 46variable arguments in an ANSI C function header). You can only use 47<code>va_start</code> in a function declared using this ellipsis notation 48(not, for example, in one of its subfunctions). 49 50 <p><strong>Returns</strong><br> 51<code>va_start</code> does not return a result. 52 53 <p><strong>Portability</strong><br> 54ANSI C requires <code>va_start</code>. 55 56 </body></html> 57 58