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

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<a name="Variable-Attributes"></a>
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<p>
Next: <a href="Type-Attributes.html#Type-Attributes" accesskey="n" rel="next">Type Attributes</a>, Previous: <a href="Function-Attributes.html#Function-Attributes" accesskey="p" rel="prev">Function Attributes</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="Specifying-Attributes-of-Variables"></a>
<h3 class="section">6.32 Specifying Attributes of Variables</h3>
<a name="index-attribute-of-variables"></a>
<a name="index-variable-attributes"></a>

<p>The keyword <code>__attribute__</code> allows you to specify special
attributes of variables or structure fields.  This keyword is followed
by an attribute specification inside double parentheses.  Some
attributes are currently defined generically for variables.
Other attributes are defined for variables on particular target
systems.  Other attributes are available for functions
(see <a href="Function-Attributes.html#Function-Attributes">Function Attributes</a>), labels (see <a href="Label-Attributes.html#Label-Attributes">Label Attributes</a>),
enumerators (see <a href="Enumerator-Attributes.html#Enumerator-Attributes">Enumerator Attributes</a>), statements
(see <a href="Statement-Attributes.html#Statement-Attributes">Statement Attributes</a>), and for types (see <a href="Type-Attributes.html#Type-Attributes">Type Attributes</a>).
Other front ends might define more attributes
(see <a href="C_002b_002b-Extensions.html#C_002b_002b-Extensions">Extensions to the C++ Language</a>).
</p>
<p>See <a href="Attribute-Syntax.html#Attribute-Syntax">Attribute Syntax</a>, for details of the exact syntax for using
attributes.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="Common-Variable-Attributes.html#Common-Variable-Attributes" accesskey="1">Common Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="AVR-Variable-Attributes.html#AVR-Variable-Attributes" accesskey="2">AVR Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Blackfin-Variable-Attributes.html#Blackfin-Variable-Attributes" accesskey="3">Blackfin Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="H8_002f300-Variable-Attributes.html#H8_002f300-Variable-Attributes" accesskey="4">H8/300 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="IA_002d64-Variable-Attributes.html#IA_002d64-Variable-Attributes" accesskey="5">IA-64 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="M32R_002fD-Variable-Attributes.html#M32R_002fD-Variable-Attributes" accesskey="6">M32R/D Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="MeP-Variable-Attributes.html#MeP-Variable-Attributes" accesskey="7">MeP Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Microsoft-Windows-Variable-Attributes.html#Microsoft-Windows-Variable-Attributes" accesskey="8">Microsoft Windows Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="MSP430-Variable-Attributes.html#MSP430-Variable-Attributes" accesskey="9">MSP430 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Nvidia-PTX-Variable-Attributes.html#Nvidia-PTX-Variable-Attributes">Nvidia PTX Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="PowerPC-Variable-Attributes.html#PowerPC-Variable-Attributes">PowerPC Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="RL78-Variable-Attributes.html#RL78-Variable-Attributes">RL78 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="SPU-Variable-Attributes.html#SPU-Variable-Attributes">SPU Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="V850-Variable-Attributes.html#V850-Variable-Attributes">V850 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="x86-Variable-Attributes.html#x86-Variable-Attributes">x86 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Xstormy16-Variable-Attributes.html#Xstormy16-Variable-Attributes">Xstormy16 Variable Attributes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

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Next: <a href="Type-Attributes.html#Type-Attributes" accesskey="n" rel="next">Type Attributes</a>, Previous: <a href="Function-Attributes.html#Function-Attributes" accesskey="p" rel="prev">Function Attributes</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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