1<html lang="en"> 2<head> 3<title>fileno - 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="Stdio.html#Stdio" title="Stdio"> 9<link rel="prev" href="fgetws.html#fgetws" title="fgetws"> 10<link rel="next" href="fmemopen.html#fmemopen" title="fmemopen"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<meta http-equiv="Content-Style-Type" content="text/css"> 13<style type="text/css"><!-- 14 pre.display { font-family:inherit } 15 pre.format { font-family:inherit } 16 pre.smalldisplay { font-family:inherit; font-size:smaller } 17 pre.smallformat { font-family:inherit; font-size:smaller } 18 pre.smallexample { font-size:smaller } 19 pre.smalllisp { font-size:smaller } 20 span.sc { font-variant:small-caps } 21 span.roman { font-family:serif; font-weight:normal; } 22 span.sansserif { font-family:sans-serif; font-weight:normal; } 23--></style> 24<link rel="stylesheet" type="text/css" href="../cs.css"> 25</head> 26<body> 27<div class="node"> 28<a name="fileno"></a> 29<p> 30Next: <a rel="next" accesskey="n" href="fmemopen.html#fmemopen">fmemopen</a>, 31Previous: <a rel="previous" accesskey="p" href="fgetws.html#fgetws">fgetws</a>, 32Up: <a rel="up" accesskey="u" href="Stdio.html#Stdio">Stdio</a> 33<hr> 34</div> 35 36<h3 class="section">4.15 <code>fileno</code>—return file descriptor associated with stream</h3> 37 38<p><a name="index-fileno-176"></a><strong>Synopsis</strong> 39<pre class="example"> #include <stdio.h> 40 int fileno(FILE *<var>fp</var>); 41 42</pre> 43 <p><strong>Description</strong><br> 44You can use <code>fileno</code> to return the file descriptor identified by <var>fp</var>. 45 46 <p><br> 47<strong>Returns</strong><br> 48<code>fileno</code> returns a non-negative integer when successful. 49If <var>fp</var> is not an open stream, <code>fileno</code> returns -1. 50 51 <p><br> 52<strong>Portability</strong><br> 53<code>fileno</code> is not part of ANSI C. 54POSIX requires <code>fileno</code>. 55 56 <p>Supporting OS subroutines required: none. 57 58 <p><br> 59 60 </body></html> 61 62