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 <p>
 Previous: <a href="Working-with-Pointers.html#Working-with-Pointers" accesskey="p" rel="prev">Working with Pointers</a>, Up: <a href="Interoperability-with-C.html#Interoperability-with-C" accesskey="u" rel="up">Interoperability with C</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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 <hr>
 <a name="Further-Interoperability-of-Fortran-with-C-1"></a>
 <h4 class="subsection">7.1.6 Further Interoperability of Fortran with C</h4>

 <p>The Technical Specification ISO/IEC TS 29113:2012 on further
 interoperability of Fortran with C extends the interoperability support
 of Fortran 2003 and Fortran 2008. Besides removing some restrictions
 and constraints, it adds assumed-type (<code>TYPE(*)</code>) and assumed-rank
 (<code>dimension</code>) variables and allows for interoperability of
 assumed-shape, assumed-rank and deferred-shape arrays, including
 allocatables and pointers.
 </p>
 <p>Note: Currently, GNU Fortran does not support the array descriptor
 (dope vector) as specified in the Technical Specification, but uses
 an array descriptor with different fields. The Chasm Language
 Interoperability Tools, <a href="http://chasm-interop.sourceforge.net/">http://chasm-interop.sourceforge.net/</a>,
 provide an interface to GNU Fortran&rsquo;s array descriptor.
 </p>
 <p>The Technical Specification adds the following new features, which
 are supported by GNU Fortran:
 </p>
 <ul>
 <li> The <code>ASYNCHRONOUS</code> attribute has been clarified and
 extended to allow its use with asynchronous communication in
 user-provided libraries such as in implementations of the
 Message Passing Interface specification.

 </li><li> Many constraints have been relaxed, in particular for
 the <code>C_LOC</code> and <code>C_F_POINTER</code> intrinsics.

 </li><li> The <code>OPTIONAL</code> attribute is now allowed for dummy
 arguments; an absent argument matches a <code>NULL</code> pointer.

 </li><li> Assumed types (<code>TYPE(*)</code>) have been added, which may
 only be used for dummy arguments.  They are unlimited polymorphic
 but contrary to <code>CLASS(*)</code> they do not contain any type
 information, similar to C&rsquo;s <code>void *</code> pointers.  Expressions
 of any type and kind can be passed; thus, it can be used as
 replacement for <code>TYPE(C_PTR)</code>, avoiding the use of
 <code>C_LOC</code> in the caller.

 <p>Note, however, that <code>TYPE(*)</code> only accepts scalar arguments,
 unless the <code>DIMENSION</code> is explicitly specified.  As
 <code>DIMENSION(*)</code> only supports array (including array elements) but
 no scalars, it is not a full replacement for <code>C_LOC</code>.  On the
 other hand, assumed-type assumed-rank dummy arguments
 (<code>TYPE(*), DIMENSION(..)</code>) allow for both scalars and arrays, but
 require special code on the callee side to handle the array descriptor.
 </p>
 </li><li> Assumed-rank arrays (<code>DIMENSION(..)</code>) as dummy argument
 allow that scalars and arrays of any rank can be passed as actual
 argument. As the Technical Specification does not provide for direct
 means to operate with them, they have to be used either from the C side
 or be converted using <code>C_LOC</code> and <code>C_F_POINTER</code> to scalars
 or arrays of a specific rank. The rank can be determined using the
 <code>RANK</code> intrinisic.
 </li></ul>


 <p>Currently unimplemented:
 </p>
 <ul>
 <li> GNU Fortran always uses an array descriptor, which does not
 match the one of the Technical Specification. The
 <code>ISO_Fortran_binding.h</code> header file and the C functions it
 specifies are not available.

 </li><li> Using assumed-shape, assumed-rank and deferred-shape arrays in
 <code>BIND(C)</code> procedures is not fully supported. In particular,
 C interoperable strings of other length than one are not supported
 as this requires the new array descriptor.
 </li></ul>


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 Previous: <a href="Working-with-Pointers.html#Working-with-Pointers" accesskey="p" rel="prev">Working with Pointers</a>, Up: <a href="Interoperability-with-C.html#Interoperability-with-C" accesskey="u" rel="up">Interoperability with C</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="Further-Interoperability-of-Fortran-with-C"></a>
	<div class="header">
	<p>
	Previous: <a href="Working-with-Pointers.html#Working-with-Pointers" accesskey="p" rel="prev">Working with Pointers</a>, Up: <a href="Interoperability-with-C.html#Interoperability-with-C" accesskey="u" rel="up">Interoperability with C</a>   [<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>
	</div>
	<hr>
	<a name="Further-Interoperability-of-Fortran-with-C-1"></a>
	<h4 class="subsection">7.1.6 Further Interoperability of Fortran with C</h4>

	<p>The Technical Specification ISO/IEC TS 29113:2012 on further
	interoperability of Fortran with C extends the interoperability support
	of Fortran 2003 and Fortran 2008. Besides removing some restrictions
	and constraints, it adds assumed-type (<code>TYPE(*)</code>) and assumed-rank
	(<code>dimension</code>) variables and allows for interoperability of
	assumed-shape, assumed-rank and deferred-shape arrays, including
	allocatables and pointers.
	</p>
	<p>Note: Currently, GNU Fortran does not support the array descriptor
	(dope vector) as specified in the Technical Specification, but uses
	an array descriptor with different fields. The Chasm Language
	Interoperability Tools, <a href="http://chasm-interop.sourceforge.net/">http://chasm-interop.sourceforge.net/</a>,
	provide an interface to GNU Fortran’s array descriptor.
	</p>
	<p>The Technical Specification adds the following new features, which
	are supported by GNU Fortran:
	</p>
	<ul>
	<li> The <code>ASYNCHRONOUS</code> attribute has been clarified and
	extended to allow its use with asynchronous communication in
	user-provided libraries such as in implementations of the
	Message Passing Interface specification.

	</li><li> Many constraints have been relaxed, in particular for
	the <code>C_LOC</code> and <code>C_F_POINTER</code> intrinsics.

	</li><li> The <code>OPTIONAL</code> attribute is now allowed for dummy
	arguments; an absent argument matches a <code>NULL</code> pointer.

	</li><li> Assumed types (<code>TYPE(*)</code>) have been added, which may
	only be used for dummy arguments. They are unlimited polymorphic
	but contrary to <code>CLASS(*)</code> they do not contain any type
	information, similar to C’s <code>void *</code> pointers. Expressions
	of any type and kind can be passed; thus, it can be used as
	replacement for <code>TYPE(C_PTR)</code>, avoiding the use of
	<code>C_LOC</code> in the caller.

	<p>Note, however, that <code>TYPE(*)</code> only accepts scalar arguments,
	unless the <code>DIMENSION</code> is explicitly specified. As
	<code>DIMENSION(*)</code> only supports array (including array elements) but
	no scalars, it is not a full replacement for <code>C_LOC</code>. On the
	other hand, assumed-type assumed-rank dummy arguments
	(<code>TYPE(*), DIMENSION(..)</code>) allow for both scalars and arrays, but
	require special code on the callee side to handle the array descriptor.
	</p>
	</li><li> Assumed-rank arrays (<code>DIMENSION(..)</code>) as dummy argument
	allow that scalars and arrays of any rank can be passed as actual
	argument. As the Technical Specification does not provide for direct
	means to operate with them, they have to be used either from the C side
	or be converted using <code>C_LOC</code> and <code>C_F_POINTER</code> to scalars
	or arrays of a specific rank. The rank can be determined using the
	<code>RANK</code> intrinisic.
	</li></ul>


	<p>Currently unimplemented:
	</p>
	<ul>
	<li> GNU Fortran always uses an array descriptor, which does not
	match the one of the Technical Specification. The
	<code>ISO_Fortran_binding.h</code> header file and the C functions it
	specifies are not available.

	</li><li> Using assumed-shape, assumed-rank and deferred-shape arrays in
	<code>BIND(C)</code> procedures is not fully supported. In particular,
	C interoperable strings of other length than one are not supported
	as this requires the new array descriptor.
	</li></ul>


	<hr>
	<div class="header">
	<p>
	Previous: <a href="Working-with-Pointers.html#Working-with-Pointers" accesskey="p" rel="prev">Working with Pointers</a>, Up: <a href="Interoperability-with-C.html#Interoperability-with-C" accesskey="u" rel="up">Interoperability with C</a>   [<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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