hdf5/doc/html/RM_H5I.html
Frank Baker 31b8c66d0b [svn-r9224]
Purpose:
    Add h5iget_file_id_f
Platforms tested:
    Mozilla
2004-09-08 12:27:48 -05:00

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HDF5/H5I API Specification
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<h1>H5I: Identifier Interface</h1>
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<h2>Identifier API Functions</h2>
These functions provides tools for working with object identifiers and
object names.
<p>
<strong>The C Interface:</strong>
<table border=0>
<tr><td valign=top>
<ul>
<li><a href="#Identify-GetFileId">H5Iget_file_id</a>
<li><a href="#Identify-GetName">H5Iget_name</a>
<li><a href="#Identify-GetType">H5Iget_type</a>
<li><a href="#Identify-ObjectVerify">H5Iobject_verify</a>
<li><a href="#Identify-RemoveVerify">H5Iremove_verify</a>
<li><a href="#Identify-Search">H5Isearch</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
<li><a href="#Identify-GetRef">H5Iget_ref</a>
<li><a href="#Identify-IncRef">H5Iinc_ref</a>
<li><a href="#Identify-DecRef">H5Idec_ref</a>
<li><a href="#Identify-Register">H5Iregister</a>
<li><a href="#Identify-RegisterType">H5Iregister_type</a>
<li><a href="#Identify-DestroyType">H5Idestroy_type</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
<li><a href="#Identify-GetTypeRef">H5Iget_type_ref</a>
<li><a href="#Identify-DecTypeRef">H5Idec_type_ref</a>
<li><a href="#Identify-IncTypeRef">H5Iinc_type_ref</a>
<li><a href="#Identify-ClearType">H5Iclear_type</a>
<li><a href="#Identify-NMembers">H5Inmembers</a>
</ul>
</td></tr>
</table>
<br>
<i>Alphabetical Listing</i>
<table border="0">
<tr>
<td valign="top">
<ul>
<li><a href="#Identify-ClearType">H5Iclear_type</a>
<li><a href="#Identify-DecRef">H5Idec_ref</a>
<li><a href="#Identify-DecTypeRef">H5Idec_type_ref</a>
<li><a href="#Identify-DestroyType">H5Idestroy_type</a>
<li><a href="#Identify-GetFileId">H5Iget_file_id</a>
<li><a href="#Identify-GetName">H5Iget_name</a>
</ul>
</td>
<td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
<td valign="top">
<ul>
<li><a href="#Identify-GetRef">H5Iget_ref</a>
<li><a href="#Identify-GetType">H5Iget_type</a>
<li><a href="#Identify-GetTypeRef">H5Iget_type_ref</a>
<li><a href="#Identify-IncRef">H5Iinc_ref</a>
<li><a href="#Identify-IncTypeRef">H5Iinc_type_ref</a>
<li><a href="#Identify-NMembers">H5Inmembers</a>
</ul>
</td>
<td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
<td valign="top">
<ul>
<li><a href="#Identify-ObjectVerify">H5Iobject_verify</a>
<li><a href="#Identify-Register">H5Iregister</a>
<li><a href="#Identify-RegisterType">H5Iregister_type</a>
<li><a href="#Identify-RemoveVerify">H5Iremove_verify</a>
<li><a href="#Identify-Search">H5Isearch</a>
</ul>
</td>
</tr>
</table>
<br>
<strong>The FORTRAN90 Interfaces:</strong>
<br>
In general, each FORTRAN90 subroutine performs exactly the same task
as the corresponding C function.
<br>
<table border=0>
<tr><td valign=top>
<ul>
<li><a href="#Identify-GetType">h5iget_type_f</a>
<li><a href="#Identify-GetName">h5iget_name_f</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
<li><a href="#Identify-GetRef">h5iget_ref_f</a>
<li><a href="#Identify-IncRef">h5iinc_ref_f</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
<li><a href="#Identify-DecRef">h5idec_ref_f</a>
</ul>
</td></tr>
</table>
<!-- NEW PAGE -->
<!-- HEADER RIGHT " " -->
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iclear_type" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-ClearType">H5Iclear_type</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5Iclear_type</code>(<em>H5I_type_t</em> <code>type</code>,
<em>hbool_t</em> <code>force</code>)
<dt><strong>Purpose:</strong>
<dd>Deletes all IDs of the given type
<dt><strong>Description:</strong>
<dd><code>H5Iclear_type</code> deletes all IDs of the type identified by the argument type.
<p>
The type<70>s free function is first called on all of these IDs to free their memory,
then they are removed from the type.
<p>
If the <code>force</code> flag is set to false, only those IDs whose reference
counts are equal to 1 will be deleted, and all other IDs will be entirely unchanged.
If the <code>force</code> flag is true, all IDs of this type will be deleted.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Identifier of ID type which is to be cleared of IDs</td>
</tr>
<tr>
<td valign="top"><em>hbool_t</em> <code>force</code></td>
<td valign="top">IN: Whether or not to force deletion of all IDs</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns non-negative on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
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</dl>
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<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-DecRef">H5Idec_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Idec_ref</code>(<em>hid_t</em> <code>obj_id</code>)
<dt><strong>Purpose:</strong>
<dd>Decrements the reference count for an object.
<dt><strong>Description:</strong>
<dd><code>H5Idec_ref</code> decrements the reference count of the object
identified by <code>obj_id</code>.
<p>
The reference count for an object ID is attached to the information
about an object in memory and has no relation to the number of links to
an object on disk.
<p>
The reference count for a newly created object will be 1.
Reference counts for objects may be explicitly modified with this
function or with <code>H5Iinc_ref</code>.
When an object ID's reference count reaches zero, the object will be
closed.
Calling an object ID's 'close' function decrements the reference count
for the ID which normally closes the object, but
if the reference count for the ID has been incremented with
<code>H5Iinc_ref</code>, the object will only be closed when the
reference count
reaches zero with further calls to this function or the
object ID's 'close' function.
<p>
If the object ID was created by a collective parallel call (such as
<code>H5Dcreate</code>, <code>H5Gopen</code>, etc.), the reference
count should be modified by all the processes which have copies of
the ID. Generally this means that group, dataset, attribute, file
and named datatype IDs should be modified by all the processes and
that all other types of IDs are safe to modify by individual processes.
<p>
This function is of particular value when an application is maintaining
multiple copies of an object ID. The object ID can be incremented when
a copy is made. Each copy of the ID can then be safely closed or
decremented and the HDF5 object will be closed when the reference count
for that that object drops to zero.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Object identifier whose reference count will be modified.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
<dd>Returns a non-negative reference count of the object ID after
decrementing it if successful; otherwise a negative value is returned.
<dt><strong>Fortran90 Interface:</strong> h5idec_ref_f
<dd>
<pre>
SUBROUTINE h5idec_ref_f(obj_id, ref_count, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id !Object identifier
INTEGER, INTENT(OUT) :: ref_count !Reference count of object ID
INTEGER, INTENT(OUT) :: hdferr ! Error code
! 0 on success, and -1 on failure
END SUBROUTINE h5idec_ref_f
</pre>
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
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<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-DecTypeRef">H5Idec_type_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Idec_type_ref</code>(<em>H5I_type_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Decrements the reference count on an ID type.
<dt><strong>Description:</strong>
<dd><code>H5Idec_type_ref</code> decrements the reference count on an ID type.
The reference count is used by the library to indicate when an ID type can
be destroyed. If the reference count reaches zero, this function will destroy it.
<p>The <code>type</code> parameter is the identifier for the ID type whose
reference count is to be decremented. This identifier must have been
created by a call to <code>H5Iregister_type</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The identifier of the type whose reference count is to be decremented</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns the current reference count on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
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<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-DestroyType">H5Idestroy_type</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5Idestroy_type</code>(<em>H5I_type_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Removes the type <code>type</code> and all IDs within that type.
<dt><strong>Description:</strong>
<dd><code>H5Idestroy_type</code> deletes an entire ID type. All IDs of this
type are destroyed and no new IDs of this type can be registered.
<p>
The type<70>s free function is called on all of the IDs which are deleted by
this function, freeing their memory. In addition, all memory used by this
type<70>s hash table is freed.
<p>
Since the <em>H5I_type_t</em> values of destroyed ID types are reused
when new types are registered, it is a good idea to set the variable
holding the value of the destroyed type to <code>H5I_UNINIT</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Identifier of ID type which is to be destroyed</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns non-negative on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iget_file_id" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-GetFileId">H5Iget_file_id</a>
<dt><strong>Signature:</strong>
<dd><em>hid_t</em> <code>H5Iget_file_id</code>(<em>hid_t</em> <code>obj_id</code>)
<dt><strong>Purpose:</strong>
<dd>Retrieves an identifier for the file containing the specified object.
<dt><strong>Description:</strong>
<dd><code>H5Iget_file_id</code> returns the identifier of the file
associated with the object referenced by <code>obj_id</code>.
<p>
<code>obj_id</code> can be a file, group, dataset, named datatype,
or attribute identifier.
<p>
Note that the HDF5 Library permits an application to close a file
while objects within the file remain open.
If the file containing the object <code>obj_id</code>
is still open, <code>H5Iget_file_id</code> will retrieve the
existing file identifier.
If there is no existing file identifier for the file,
i.e., the file has been closed,
<code>H5Iget_file_id</code> will reopen the file and
return a new file identifier.
In either case, the file identifier must eventually be released
using <code>H5Fclose</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code>
</td>
<td valign="top">IN: Identifier of the object whose associated
file identifier will be returned.</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns a file identifier on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>
<pre>
SUBROUTINE h5iget_file_id_f(obj_id, file_id, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id ! Object identifier
INTEGER(HID_T), INTENT(OUT) :: file_id ! File identifier
INTEGER, INTENT(OUT) :: hdferr ! Error code
END SUBROUTINE h5iget_file_id_f
</pre>
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iget_name" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-GetName">H5Iget_name</a>
<dt><strong>Signature:</strong>
<dd><em>ssize_t</em> <code>H5Iget_name</code>(<em>hid_t</em> <code>obj_id</code>,
<em>char *</em><code>name</code>,
<em>size_t</em> <code>size</code>
)
<dt><strong>Purpose:</strong> </dt>
<dd>Retrieves a name of an object based on the object identifier.
<dt><strong>Description:</strong>
<dd><code>H5Iget_name</code> retrieves a name for the object identified
by <code>obj_id</code>.
<p>
Up to <code>size</code> characters of the name are returned in
<code>name</code>; additional characters, if any, are not returned
to the user application.
<p>
If the length of the name, which determines the required
value of <code>size</code>, is unknown, a preliminary
<code>H5Iget_name</code> call can be made.
The return value of this call will be the size of the
object name.
That value can then be assigned to <code>size</code>
for a second <code>H5Iget_name</code> call,
which will retrieve the actual name.
<p>
If there is no name associated with the object identifier
or if the name is <code>NULL</code>, <code>H5Iget_name</code>
returns <code>0</code> (zero).
<p>
Note that an object in an HDF5 file may have multiple names,
varying according to the path through the HDF5 group
hierarchy used to reach that object.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Identifier of the object.
This identifier can refer to a group, dataset, or named datatype.</td></tr>
<tr>
<td valign="top"><em>char *</em><code>name</code></td>
<td valign="top">OUT: A name associated with the identifier.</td></tr>
<tr>
<td valign="top"><em>size_t size</em></td>
<td valign="top">IN: The size of the <code>name</code> buffer.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
<dd>Returns the length of the name if successful,
returning <code>0</code> (zero) if no name is associated with the identifier.
Otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong> h5iget_name_f
<dd>
<pre>
SUBROUTINE h5iget_name_f(obj_id, buf, buf_size, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id ! Object identifier
CHARACTER(LEN=*), INTENT(OUT) :: buf ! Buffer to hold object name
INTEGER(SIZE_T), INTENT(IN) :: buf_size ! Buffer size
INTEGER(SIZE_T), INTENT(OUT) :: name_size ! Name size
INTEGER, INTENT(OUT) :: hdferr ! Error code
! 0 on success, and -1 on failure
END SUBROUTINE h5iget_name_f
</pre>
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iget_ref" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-GetRef">H5Iget_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Iget_ref</code>(<em>hid_t</em> <code>obj_id</code>)
<dt><strong>Purpose:</strong>
<dd>Retrieves the reference count for an object.
<dt><strong>Description:</strong>
<dd><code>H5Iget_ref</code> retrieves the reference count of the object
identified by <code>obj_id</code>.
<p>
The reference count for an object ID is attached to the information
about an object in memory and has no relation to the number of links to
an object on disk.
<p>
This function can also be used to check if an object ID is still valid.
A non-negative return value from this function indicates that the ID
is still valid.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Object identifier whose reference count will be retrieved.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
<dd>Returns a non-negative current reference count of the object ID
if successful; otherwise a negative value is returned.
<dt><strong>Fortran90 Interface:</strong> h5iget_ref_f
<dd>
<pre>
SUBROUTINE h5iget_ref_f(obj_id, ref_count, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id !Object identifier
INTEGER, INTENT(OUT) :: ref_count !Reference count of object ID
INTEGER, INTENT(OUT) :: hdferr ! Error code
! 0 on success, and -1 on failure
END SUBROUTINE h5iget_ref_f
</pre>
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iget_type" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-GetType">H5Iget_type</a>
<dt><strong>Signature:</strong>
<dd><em>H5I_type_t</em> <code>H5Iget_type</code>(<em>hid_t</em> <code>obj_id</code>)
<dt><strong>Purpose:</strong>
<dd>Retrieves the type of an object.
<dt><strong>Description:</strong>
<dd><code>H5Iget_type</code> retrieves the type of the object
identified by <code>obj_id</code>.
<p>
Valid types returned by the function are
<table>
<tr><td width=200><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_FILE</code>
</td><td>File</td></tr>
<tr><td><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_GROUP</code>
</td><td>Group</td></tr>
<tr><td><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_DATATYPE</code>
</td><td>Datatype</td></tr>
<tr><td><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_DATASPACE</code>
</td><td>Dataspace</td></tr>
<tr><td><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_DATASET</code>
</td><td>Dataset</td></tr>
<tr><td><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_ATTR</code>
</td><td>Attribute</td></tr>
</table>
If no valid type can be determined or the identifier
submitted is invalid, the function returns
<table>
<tr><td width=200><code>&nbsp;&nbsp;&nbsp;&nbsp;H5I_BADID</code>
</td><td>Invalid identifier</td></tr>
</table>
<p>
This function is of particular value in determining the
type of object closing function (<code>H5Dclose</code>,
<code>H5Gclose</code>, etc.) to call after a call to
<code>H5Rdereference</code>.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Object identifier whose type is to be determined.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
<dd>Returns the object type if successful;
otherwise <code>H5I_BADID</code>.
<dt><strong>Fortran90 Interface:</strong> h5iget_type_f
<dd>
<pre>
SUBROUTINE h5iget_type_f(obj_id, type, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id !Object identifier
INTEGER, INTENT(OUT) :: type !type of an object.
!possible values are:
!H5I_FILE_F
!H5I_GROUP_F
!H5I_DATATYPE_F
!H5I_DATASPACE_F
!H5I_DATASET_F
!H5I_ATTR_F
!H5I_BADID_F
INTEGER, INTENT(OUT) :: hdferr ! E rror code
! 0 on success, and -1 on failure
END SUBROUTINE h5iget_type_f
</pre>
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<dd>
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</dl>
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<!-- HEADER RIGHT "H5Iget_type_ref" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-GetTypeRef">H5Iget_type_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Iget_type_ref</code>(<em>H5I_type_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Retrieves the reference count on an ID type.
<dt><strong>Description:</strong>
<dd><code>H5Iget_type_ref</code> retrieves the reference count on an ID type.
The reference count is used by the library to indicate when an
ID type can be destroyed.
<p>
The <code>type</code> parameter is the identifier for the ID type whose
reference count is to be retrieved. This identifier must have been created
by a call to <code>H5Iregister_type</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The identifier of the type whose reference count is to be retrieved</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns the current reference count on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
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<dd>
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<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-IncRef">H5Iinc_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Iinc_ref</code>(<em>hid_t</em> <code>obj_id</code>)
<dt><strong>Purpose:</strong>
<dd>Increments the reference count for an object.
<dt><strong>Description:</strong>
<dd><code>H5Iinc_ref</code> increments the reference count of the object
identified by <code>obj_id</code>.
<p>
The reference count for an object ID is attached to the information
about an object in memory and has no relation to the number of links to
an object on disk.
<p>
The reference count for a newly created object will be 1.
Reference counts for objects may be explicitly modified with this
function or with <code>H5Idec_ref</code>.
When an object ID's reference count reaches zero, the object will be
closed.
Calling an object ID's 'close' function decrements the reference count
for the ID which normally closes the object, but
if the reference count for the ID has been incremented with this
function, the object will only be closed when the reference count
reaches zero with further calls to <code>H5Idec_ref</code> or the
object ID's 'close' function.
<p>
If the object ID was created by a collective parallel call (such as
<code>H5Dcreate</code>, <code>H5Gopen</code>, etc.), the reference
count should be modified by all the processes which have copies of
the ID. Generally this means that group, dataset, attribute, file
and named datatype IDs should be modified by all the processes and
that all other types of IDs are safe to modify by individual processes.
<p>
This function is of particular value when an application is maintaining
multiple copies of an object ID. The object ID can be incremented when
a copy is made. Each copy of the ID can then be safely closed or
decremented and the HDF5 object will be closed when the reference count
for that that object drops to zero.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em>&nbsp;<code>obj_id&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Object identifier whose reference count will be modified.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
<dd>Returns a non-negative reference count of the object ID after
incrementing it if successful; otherwise a negative value is returned.
<dt><strong>Fortran90 Interface:</strong> h5iinc_ref_f
<dd>
<pre>
SUBROUTINE h5iinc_ref_f(obj_id, ref_count, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: obj_id !Object identifier
INTEGER, INTENT(OUT) :: ref_count !Reference count of object ID
INTEGER, INTENT(OUT) :: hdferr ! Error code
! 0 on success, and -1 on failure
END SUBROUTINE h5iinc_ref_f
</pre>
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<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-IncTypeRef">H5Iinc_type_ref</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Iinc_type_ref</code>(<em>H5I_type_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Increments the reference count on an ID type.
<dt><strong>Description:</strong>
<dd><code>H5Iinc_type_ref</code> increments the reference count on an ID type.
The reference count is used by the library to indicate when an ID type can be destroyed.
<p>
The <code>type</code> parameter is the identifier for the ID type whose
reference count is to be incremented. This identifier must have been created
by a call to <code>H5Iregister_type</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The identifier of the type whose reference count is to be incremented</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns the current reference count on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
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-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Inmembers" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-NMembers">H5Inmembers</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Inmembers</code>(<em>H5I_type_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Returns the number of IDs in a given type.
<dt><strong>Description:</strong>
<dd><code>H5Inmembers</code> returns the number of IDs of a given ID type.
If no IDs of this type have been registered, H5Inmembers returns 0.
If the type does not exist or has been destroyed, <code>H5Inmembers</code>
also returns 0.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Identifier of ID type whose member count will be retrieved</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns number of members on success, zero if type is not a valid ID type.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iobject_verify" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-ObjectVerify">H5Iobject_verify</a>
<dt><strong>Signature:</strong>
<dd><em>void *</em> <code>H5Iobject_verify</code>(<em>hid_t</em> <code>id</code>,
<em>H5I_type_t</em> <code>id_type</code>)
<dt><strong>Purpose:</strong>
<dd>Returns the object referenced by id.
<dt><strong>Description:</strong>
<dd><code>H5Iobject_verify</code> returns a pointer to the memory referenced by
<code>id</code> after verifying that <code>id</code> is of type <code>id_type</code>.
This function is analogous to dereferencing a pointer in C with type checking.
<p>
<code>H5Iregister</code>(<em>H5I_type_t</em> <code>type</code>,
<em>void *</em><code>object</code>) takes an <em>H5I_type_t</em> and a
void pointer to an object, returning an <em>hid_t</em> of that type.
This <em>hid_t</em> can then be passed to <code>H5Iobject_verify</code>
along with its type to retrieve the object.
<p>
<code>H5Iobject_verify</code> does not change the ID it is called on in any
way (as opposed to <code>H5Iremove_verify</code>, which removes the ID from its
type<70>s hash table).
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>hid_t</em> <code>id</code></td>
<td valign="top">IN: ID to be dereferenced</td>
</tr>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: ID type to which id should belong</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Pointer to the object referenced by id on success, <code>NULL</code> on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
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<!-- HEADER RIGHT "H5Iregister" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-Register">H5Iregister</a>
<dt><strong>Signature:</strong>
<dd><em>hid_t</em> <code>H5Iregister</code>(<em>H5I_type_t</em> <code>type</code>,
<em>void *</em><code>object</code>)
<dt><strong>Purpose:</strong>
<dd>Creates and returns a new ID.
<dt><strong>Description:</strong>
<dd><code>H5Iregister</code> allocates space for a new ID and returns an identifier for it.
<p>
The <code>type</code> parameter is the identifier for the ID type to which
this new ID will belong. This identifier must have been created by a call
to <code>H5Iregister_type</code>.
<p>
The <code>object</code> parameter is a pointer to the memory which the new
ID will be a reference to. This pointer will be stored by the library and
returned to you via a call to <code>H5Iobject_verify</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The identifier of the type to which the new ID will belong</td>
</tr>
<tr>
<td valign="top"><em>void *</em><code>object</code></td>
<td valign="top">IN: Pointer to memory for the library to store</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns the new ID on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iregister_type" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-RegisterType">H5Iregister_type</a>
<dt><strong>Signature:</strong>
<dd><em>H5I_type_t</em> <code>H5Iregister_type</code>(<em>size_t</em>
<code>hash_size</code>, <em>unsigned</em> <code>reserved</code>,
<em>H5I_free_t</em> <code>free_func</code>)
<dt><strong>Purpose:</strong>
<dd>Creates and returns a new ID type.
<dt><strong>Description:</strong>
<dd><code>H5Iregister_type</code> allocates space for a new ID type and
returns an identifier for it.
<p>
The <code>hash_size</code> parameter indicates the minimum size of the hash
table used to store IDs in the new type.
<p>
The <code>reserved</code> parameter indicates the number of IDs in this new
type to be reserved. Reserved IDs are valid IDs which are not associated with
any storage within the library.
<p>
The <code>free_func</code> parameter is a function pointer to a function
which returns an <em>herr_t</em> and accepts a <em>void *</em>. The purpose
of this function is to deallocate memory for a single ID. It will be called
by <code>H5Iclear_type</code> and <code>H5Idestroy_type</code> on each ID.
This function is NOT called by <code>H5Iremove_verify</code>.
The <em>void *</em> will be the same pointer which was passed in to
the <code>H5Iregister</code> function. The <code>free_func</code>
function should return 0 on success and -1 on failure.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>size_t</em> <code>hash_size</code></td>
<td valign="top">IN: Size of the hash table (in entries) used to store IDs for the new type</td>
</tr>
<tr>
<td valign="top"><em>unsigned</em> <code>reserved</code></td>
<td valign="top">IN: Number of reserved IDs for the new type</td>
</tr>
<tr>
<td valign="top"><em>H5I_free_t</em>&nbsp;<code>free_func&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Function used to deallocate space for a single ID</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns the type identifier on success, negative on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iremove_verify" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-RemoveVerify">H5Iremove_verify</a>
<dt><strong>Signature:</strong>
<dd><em>void *</em><code>H5Iremove_verify</code>(<em>hid_t</em> <code>id</code>,
<em>H5I_type_t</em> <code>id_type</code>)
<dt><strong>Purpose:</strong>
<dd>Removes an ID from internal storage.
<dt><strong>Description:</strong>
<dd><code>H5Iremove_verify</code> first ensures that <code>id</code> belongs to
<code>id_type</code>. If so, it removes <code>id</code> from internal storage
and returns the pointer to the memory it referred to. This pointer is the
same pointer that was placed in storage by <code>H5Iregister</code>.
If <code>id</code> does not belong to <code>id_type</code>,
then <code>NULL</code> is returned.
<p>
The <code>id</code> parameter is the ID which is to be removed from
internal storage. Note: this function does NOT deallocate the memory that
<code>id</code> refers to. The pointer returned by <code>H5Iregister</code>
must be deallocated by the user to avoid memory leaks.
<p>
The <code>type</code> parameter is the identifier for the ID type
which <code>id</code> is supposed to belong to. This identifier must
have been created by a call to <code>H5Iregister_type</code>.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>hid_t</em> <code>id</code></td>
<td valign="top">IN: The ID to be removed from internal storage</td>
</tr>
<tr>
<td valign="top"><em>H5I_type_t</em>&nbsp;<code>type&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The identifier of the type whose reference count is to be retrieved</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns a pointer to the memory referred to by <code>id</code>
on success, <code>NULL</code> on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
</dl>
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Isearch" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Identify-Search">H5Isearch</a>
<dt><strong>Signature:</strong>
<dd><em>void *</em><code>H5Isearch</code>(<em>H5I_type_t</em> <code>type</code>,
<em>H5I_search_func_t</em> <code>func</code>, <em>void *</em><code>key</code>)
<dt><strong>Purpose:</strong>
<dd>Finds the memory referred to by an ID within the given ID type such that
some criterion is satisfied.
<dt><strong>Description:</strong>
<dd><code>H5Isearch</code> searches through a give ID type to find an object
that satisfies the criteria defined by <code>func</code>. If such an object
is found, the pointer to the memory containing this object is returned.
Otherwise, <code>NULL</code> is returned. To do this, <code>func</code> is
called on every member of <code>type</code>. The first member to satisfy
<code>func</code> is returned.
<p>
The <code>type</code> parameter is the identifier for the ID type which is
to be searched. This identifier must have been created by a call to
<code>H5Iregister_type</code>.
<p>
The parameter <code>func</code> is a function pointer to a function
which takes three parameters. The first parameter is a <em>void *</em>.
It will be a pointer the object to be tested. This is the same object
that was placed in storage using <code>H5Iregister</code>. The second
parameter is a <em>hid_t</em>. It is the ID of the object to be tested.
The last parameter is a <em>void *</em>. This is the <code>key</code> parameter
and can be used however the user finds helpful. Or it can simply be ignored
if it is not needed. <code>func</code> returns 0 if the object it is testing
does not pass its criteria. A non-zero value should be returned if the object
does pass its criteria.
<p>
The <code>key</code> parameter will be passed to the search function as a
parameter. It can be used to further define the search at run-time.
<dt><strong>Parameters:</strong>
<ul>
<table>
<tr>
<td valign="top"><em>H5I_type_t</em> <code>type</code></td>
<td valign="top">IN: The identifier of the type to be searched</td>
</tr>
<tr>
<td valign="top"><em>H5I_search_func_t</em>&nbsp;<code>func&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: The function defining the search criteria</td>
</tr>
<tr>
<td valign="top"><em>void *</em><code>key</code></td>
<td valign="top">IN: A key for the search function</td>
</tr>
</table>
</ul>
<dt><strong>Returns:</strong>
<dd>Returns a pointer to the object which satisfies the search function
on success, <code>NULL</code> on failure.
<dt><strong>Fortran90 Interface:</strong>
<dd>This function is not supported in FORTRAN 90.
<!--<dt><strong>Non-C API(s):</strong>
<dd>
<img src="Graphics/Java.gif">
<img src="Graphics/C++.gif">
-->
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Describes HDF5 Release 1.7, the unreleased development branch; working toward HDF5 Release 1.8.0
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