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<title>Using the GNU Compiler Collection (GCC): Subscripting</title>

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<a name="Subscripting"></a>
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Next: <a href="Pointer-Arith.html#Pointer-Arith" accesskey="n" rel="next">Pointer Arith</a>, Previous: <a href="Escaped-Newlines.html#Escaped-Newlines" accesskey="p" rel="prev">Escaped Newlines</a>, Up: <a href="C-Extensions.html#C-Extensions" accesskey="u" rel="up">C Extensions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Non_002dLvalue-Arrays-May-Have-Subscripts"></a>
<h3 class="section">6.22 Non-Lvalue Arrays May Have Subscripts</h3>
<a name="index-subscripting"></a>
<a name="index-arrays_002c-non_002dlvalue"></a>

<a name="index-subscripting-and-function-values"></a>
<p>In ISO C99, arrays that are not lvalues still decay to pointers, and
may be subscripted, although they may not be modified or used after
the next sequence point and the unary &lsquo;<samp>&amp;</samp>&rsquo; operator may not be
applied to them.  As an extension, GNU C allows such arrays to be
subscripted in C90 mode, though otherwise they do not decay to
pointers outside C99 mode.  For example,
this is valid in GNU C though not valid in C90:
</p>
<div class="smallexample">
<pre class="smallexample">struct foo {int a[4];};

struct foo f();

bar (int index)
{
  return f().a[index];
}
</pre></div>


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