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| author | Frank Baker <fbaker@hdfgroup.org> | 2000-12-22 20:47:59 (GMT) |
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| committer | Frank Baker <fbaker@hdfgroup.org> | 2000-12-22 20:47:59 (GMT) |
| commit | c1d537db2b803d6908fe3f21f62c592c9cd2bf70 (patch) | |
| tree | 56a6cb7f00a6fbec3b071722df9705e744368073 /doc/html/Tutor/crtfile.html | |
| parent | d4c3773742b8dee426e7325fee4e8fc4015f2802 (diff) | |
| download | hdf5-c1d537db2b803d6908fe3f21f62c592c9cd2bf70.zip hdf5-c1d537db2b803d6908fe3f21f62c592c9cd2bf70.tar.gz hdf5-c1d537db2b803d6908fe3f21f62c592c9cd2bf70.tar.bz2 | |
[svn-r3196]
Purpose:
Adding Tutorial to development branch (R 1.4)
Platforms tested:
IE 5
Diffstat (limited to 'doc/html/Tutor/crtfile.html')
| -rw-r--r-- | doc/html/Tutor/crtfile.html | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/doc/html/Tutor/crtfile.html b/doc/html/Tutor/crtfile.html new file mode 100644 index 0000000..8786aab --- /dev/null +++ b/doc/html/Tutor/crtfile.html @@ -0,0 +1,224 @@ +<HTML><HEAD> +<TITLE>HDF5 Tutorial - Creating an HDF5 File +</TITLE> +</HEAD> + +<body bgcolor="#ffffff"> + +<!-- BEGIN MAIN BODY --> + +<A HREF="http://www.ncsa.uiuc.edu/"><img border=0 +src="http://www.ncsa.uiuc.edu/Images/NCSAhome/footerlogo.gif" +width=78 height=27 alt="NCSA"><P></A> + + [ <A HREF="title.html"><I>HDF5 Tutorial Top</I></A> ] +<H1> +<BIG><BIG><BIG><FONT COLOR="#c101cd">Creating an HDF5 file</FONT> +</BIG></BIG></BIG></H1> + +<hr noshade size=1> + +<BODY> +<H2>Contents:</H2> +<UL> + <LI> <A HREF="#def">What is an HDF5 file</A>? + <LI>Programming Example + <UL> + <LI> <A HREF="#desc">Description</A> + <LI> <A HREF="#rem">Remarks</A> + <LI> <A HREF="#fc">File Contents</A> + <LI> <A HREF="#ddl">File Definition in DDL</A> + </UL> +</UL> +<HR> +<A NAME="def"> +<H2>What is an HDF5 file?</h2> +<P> +An HDF5 file is a binary file which contains scientific data and supporting +metadata. The two primary objects stored in an HDF5 file are groups and +datasets. Groups and datasets will be discussed in the other sessions. +<P> +To create a file, the program application must specify a file name, file +access mode, file creation property list, and file access property list. +<P> +<UL> + <LI><B> File Creation Property List:</B><BR> + The file creation property list is used to control the file metadata. + File metadata contains information about the size of the user-block, the + size of various file data structures used by the HDF5 library, etc. +<P> + The user-block is a fixed length block of data located at the beginning + of the file which is ignored by the HDF5 library and may be used to store + any data information found to be useful to applications. +<P> + For more details, see the HDF5 documentation. In this tutorial, + the default file metadata is used. +<P> + <LI><B> File Access Property List:</B><BR> + The file access property list is used to control different methods of + performing I/O on files. See the HDF5 User's Guide for details. The default + file access property is used in this tutorial. +</UL> +<P> +The steps to create and close an HDF5 file are as follows: +<OL> + <LI> Specify the file creation and access property lists if necessary. + <LI> Create a file. + <LI> Close the file and close the property lists if necessary. +</OL> +To create an HDF5 file, the calling program must contain the following calls: + +<PRE> + file_id = H5Fcreate(filename, access_mode, create_id, access_id); + + H5Fclose(file_id); +</PRE> +<P> +<H2>Programming Example</H2> +<A NAME="desc"> +<H3><U>Description</U></H3> +The following example demonstrates how to create and close an HDF5 file. +It creates a file called 'file.h5', and then closes the file.<BR> +[ <A HREF="examples/h5_crtfile.c">Download h5_crtfile.c</A> ] +<PRE> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + + +#include <hdf5.h> +#define FILE "file.h5" + +main() { + + hid_t file_id; /* file identifier */ + herr_t status; + + /* Create a new file using default properties. */ + file_id = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT); + + /* Terminate access to the file. */ + status = H5Fclose(file_id); +} ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + +</PRE> +<A NAME="rem"> +<H3><U>Remarks</U></H3> +<UL> +<LI>The include file 'hdf5.h' contains definitions and declarations, and it must + be included in any file that uses the HDF5 library. +<P> +<LI>H5Fcreate creates an HDF5 file and returns the file identifier. +<PRE> + hid_t H5Fcreate (const char *name, unsigned flags, hid_t create_id, + hid_t access_id) +</PRE> +<UL> + <LI> The first parameter specifies the name of the file to be created. +<P> + <LI> The second parameter specifies the file access mode. H5F_ACC_TRUNC will + truncate a file if it already exists. +<P> + <LI> The third parameter specifies the file creation property list. + H5P_DEFAULT indicates that the default file creation property list is + used. + +<P> + <LI> The last parameter of H5Fcreate specifies the file access property list. + H5P_DEFAULT indicates that the default file access property list is used. + +</UL> +<P> +<LI> When a file is no longer accessed by a program, H5Fclose must be called to + release the resource used by the file. This call is mandatory. +<PRE> + herr_t H5Fclose (hid_t file_id) +</PRE> +<P> +<LI>The root group is automatically created when a file is created. + Every file has a root group and the path name of the root group is '/'. +</UL> +<A NAME="fc"> +<H3><U>File Contents</U></H3> +HDF has developed tools to examine the contents of HDF5 files. The tool used +in this tutorial is the HDF5 dumper, h5dump. h5dump is a tool that displays +the file contents in human readable form to an ASCII file in DDL. DDL (Data +Description Language) is a language that describes HDF5 objects in Backus-Naur +Form. To view the file contents, type: +<PRE> + <B>h5dump <filename></B> +</PRE> +Figure 4.1 describes the file contents of 'file.h5' using a directed graph. +Each HDF5 object is represented by a rectangle and the arrows indicate +the structure of the contents. In Fig. 4.2, 'file.h5' contains +a group object named '/' (the root group). + +<P> +<B>Fig. 4.1</B> <I>Contents of 'file.h5'</I> +<PRE> +<!-- +<IMG src="fileh5.jpg" width="205" height="208"></PRE> --> +<IMG src="img001.gif"></PRE> +Figure 4.2 is the text-description of 'file.h5' generated by h5dump. The HDF5 +file called 'file.h5' contains a group called '/'. +<P> +<B> Fig. 4.2</B> <I>'file.h5' in DDL</I> +<PRE> + + HDF5 "file.h5" { + GROUP "/" { + } + } + +</PRE> +<A NAME="ddl"> +<h3><U>File Definition in DDL</U></H3> +Figure 4.3 is the simplified DDL file definition for creating an HDF5 file. +For simplicity, a simplified DDL is used in this tutorial. A complete and +more rigorous DDL can be found in the HDF5 User's Guide. See the +<A HREF="references.html">References</A> section of this tutorial. +<P> +<B> Fig. 4.3</B> <I>HDF5 File Definition</I> +<P> + The explanation of the symbols used in the DDL: +<PRE> + + ::= defined as + <tname> a token with the name <I>tname</I> + <a> | <b> one of <a> or <b> + <a>* zero or more occurrences of <a> +</PRE> + The simplified DDL file definition: +<PRE> + <file> ::= HDF5 "<file_name>" { <root_group> } + + <root_group> ::= GROUP "/" { <group_attribute>* <group_member>* } + + <group_attribute> ::= <attribute> + + <group_member> ::= <group> | <dataset> +</PRE> +<!-- BEGIN FOOTER INFO --> + +<P><hr noshade size=1> +<font face="arial,helvetica" size="-1"> + <a href="http://www.ncsa.uiuc.edu/"><img border=0 + src="http://www.ncsa.uiuc.edu/Images/NCSAhome/footerlogo.gif" + width=78 height=27 alt="NCSA"><br> + The National Center for Supercomputing Applications</A><br> + <a href="http://www.uiuc.edu/">University of Illinois + at Urbana-Champaign</a><br> + <br> +<!-- <A HREF="helpdesk.mail.html"> --> +<A HREF="mailto:hdfhelp@ncsa.uiuc.edu"> +hdfhelp@ncsa.uiuc.edu</A> +<BR> <H6>Last Modified: August 27, 1999</H6><BR> +<!-- modified by Barbara Jones - bljones@ncsa.uiuc.edu --> +</FONT> +<BR> +<!-- <A HREF="mailto:hdfhelp@ncsa.uiuc.edu"> --> + +</BODY> +</HTML> + + + |