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<html>
<head><title>
HDF5/H5I API Specification
</title>

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<hr><!-- #EndLibraryItem --><center>
<h1>H5I: Identifier Interface</h1>
</center>

<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’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">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Idec_ref" -->
<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>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Idec_type_ref" -->
<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>

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<!-- HEADER RIGHT "H5Idestroy_type" -->
<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’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’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>


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        <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>

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    <dd>
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        <img src="Graphics/C++.gif">
        -->
</dl>

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<!-- 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>		
		
		<!--<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 "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.

                <!--<dt><strong>Non-C API(s):</strong>
        <dd>


        <img src="Graphics/Java.gif">
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Iinc_ref" -->
<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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    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
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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">
        <img src="Graphics/C++.gif">
        -->
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<!-- 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>

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<!-- 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’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>

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<!-- 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">
        -->
</dl>

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