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<title>The GNU Fortran Compiler: Extensions implemented in GNU Fortran</title>
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<a name="Extensions-implemented-in-GNU-Fortran"></a>
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Next: <a href="Extensions-not-implemented-in-GNU-Fortran.html#Extensions-not-implemented-in-GNU-Fortran" accesskey="n" rel="next">Extensions not implemented in GNU Fortran</a>, Up: <a href="Extensions.html#Extensions" accesskey="u" rel="up">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="Extensions-implemented-in-GNU-Fortran-1"></a>
<h3 class="section">6.1 Extensions implemented in GNU Fortran</h3>
<a name="index-extensions_002c-implemented"></a>
<p>GNU Fortran implements a number of extensions over standard
Fortran. This chapter contains information on their syntax and
meaning. There are currently two categories of GNU Fortran
extensions, those that provide functionality beyond that provided
by any standard, and those that are supported by GNU Fortran
purely for backward compatibility with legacy compilers. By default,
<samp>-std=gnu</samp> allows the compiler to accept both types of
extensions, but to warn about the use of the latter. Specifying
either <samp>-std=f95</samp>, <samp>-std=f2003</samp> or <samp>-std=f2008</samp>
disables both types of extensions, and <samp>-std=legacy</samp> allows both
without warning.
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<tr><td align="left" valign="top">&bull; <a href="Old_002dstyle-kind-specifications.html#Old_002dstyle-kind-specifications" accesskey="1">Old-style kind specifications</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Old_002dstyle-variable-initialization.html#Old_002dstyle-variable-initialization" accesskey="2">Old-style variable initialization</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Extensions-to-namelist.html#Extensions-to-namelist" accesskey="3">Extensions to namelist</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="X-format-descriptor-without-count-field.html#X-format-descriptor-without-count-field" accesskey="4">X format descriptor without count field</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Commas-in-FORMAT-specifications.html#Commas-in-FORMAT-specifications" accesskey="5">Commas in FORMAT specifications</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Missing-period-in-FORMAT-specifications.html#Missing-period-in-FORMAT-specifications" accesskey="6">Missing period in FORMAT specifications</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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<tr><td align="left" valign="top">&bull; <a href="I_002fO-item-lists.html#I_002fO-item-lists" accesskey="7">I/O item lists</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Q-exponent_002dletter.html#Q-exponent_002dletter" accesskey="8"><code>Q</code> exponent-letter</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="BOZ-literal-constants.html#BOZ-literal-constants" accesskey="9">BOZ literal constants</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Real-array-indices.html#Real-array-indices">Real array indices</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Unary-operators.html#Unary-operators">Unary operators</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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<tr><td align="left" valign="top">&bull; <a href="Implicitly-convert-LOGICAL-and-INTEGER-values.html#Implicitly-convert-LOGICAL-and-INTEGER-values">Implicitly convert LOGICAL and INTEGER values</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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<tr><td align="left" valign="top">&bull; <a href="Hollerith-constants-support.html#Hollerith-constants-support">Hollerith constants support</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Cray-pointers.html#Cray-pointers">Cray pointers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="CONVERT-specifier.html#CONVERT-specifier">CONVERT specifier</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OpenMP.html#OpenMP">OpenMP</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Argument-list-functions.html#Argument-list-functions">Argument list functions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
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Next: <a href="Extensions-not-implemented-in-GNU-Fortran.html#Extensions-not-implemented-in-GNU-Fortran" accesskey="n" rel="next">Extensions not implemented in GNU Fortran</a>, Up: <a href="Extensions.html#Extensions" accesskey="u" rel="up">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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