1<html lang="en"> 2<head> 3<title>Subscripting - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions"> 9<link rel="prev" href="Escaped-Newlines.html#Escaped-Newlines" title="Escaped Newlines"> 10<link rel="next" href="Pointer-Arith.html#Pointer-Arith" title="Pointer Arith"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 141998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 152010 Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation; with the 20Invariant Sections being ``Funding Free Software'', the Front-Cover 21Texts being (a) (see below), and with the Back-Cover Texts being (b) 22(see below). A copy of the license is included in the section entitled 23``GNU Free Documentation License''. 24 25(a) The FSF's Front-Cover Text is: 26 27 A GNU Manual 28 29(b) The FSF's Back-Cover Text is: 30 31 You have freedom to copy and modify this GNU Manual, like GNU 32 software. Copies published by the Free Software Foundation raise 33 funds for GNU development.--> 34<meta http-equiv="Content-Style-Type" content="text/css"> 35<style type="text/css"><!-- 36 pre.display { font-family:inherit } 37 pre.format { font-family:inherit } 38 pre.smalldisplay { font-family:inherit; font-size:smaller } 39 pre.smallformat { font-family:inherit; font-size:smaller } 40 pre.smallexample { font-size:smaller } 41 pre.smalllisp { font-size:smaller } 42 span.sc { font-variant:small-caps } 43 span.roman { font-family:serif; font-weight:normal; } 44 span.sansserif { font-family:sans-serif; font-weight:normal; } 45--></style> 46<link rel="stylesheet" type="text/css" href="../cs.css"> 47</head> 48<body> 49<div class="node"> 50<a name="Subscripting"></a> 51<p> 52Next: <a rel="next" accesskey="n" href="Pointer-Arith.html#Pointer-Arith">Pointer Arith</a>, 53Previous: <a rel="previous" accesskey="p" href="Escaped-Newlines.html#Escaped-Newlines">Escaped Newlines</a>, 54Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a> 55<hr> 56</div> 57 58<h3 class="section">6.22 Non-Lvalue Arrays May Have Subscripts</h3> 59 60<p><a name="index-subscripting-2364"></a><a name="index-arrays_002c-non_002dlvalue-2365"></a> 61<a name="index-subscripting-and-function-values-2366"></a>In ISO C99, arrays that are not lvalues still decay to pointers, and 62may be subscripted, although they may not be modified or used after 63the next sequence point and the unary ‘<samp><span class="samp">&</span></samp>’ operator may not be 64applied to them. As an extension, GCC allows such arrays to be 65subscripted in C90 mode, though otherwise they do not decay to 66pointers outside C99 mode. For example, 67this is valid in GNU C though not valid in C90: 68 69<pre class="smallexample"> struct foo {int a[4];}; 70 71 struct foo f(); 72 73 bar (int index) 74 { 75 return f().a[index]; 76 } 77</pre> 78 </body></html> 79 80