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Recall that to create an HDF5 object, we have to specify the location where the
object is to be created. This location is determined by the identifier of an HDF5
object and the name of the object to be created. The name of the created
object can be either an absolute name or a name relative to the specified
identifier.
In the previous example, we used the file identifier and the absolute name
/MyGroup to create a group.
In this section, we discuss HDF5 names and show how to use absolute and relative names.
/) and the null terminator.
A full name
may be composed of any number of component names separated by slashes, with any
of the component names being the special name . (a dot or period).
A name which begins with a slash is an absolute name which is accessed
beginning with the root group of the file;
all other names are relative names and and the named object is
accessed beginning with the specified group.
Multiple consecutive slashes in a full name are treated as single slashes
and trailing slashes are not significant. A special case is the name / (or
equivalent) which refers to the root group.
Functions which operate on names generally take a location identifier, which can be either a file identifier or a group identifier, and perform the lookup with respect to that location. Several possibilities are described in the following table:
| Location Type | Object Name | Description |
| File identifier |
/foo/bar |
The object bar in group foo
in the root group. |
| Group identifier |
/foo/bar |
The object bar in group foo in the
root group of the file containing the specified group.
In other words, the group identifier's only purpose is to
specify a file. |
| File identifier |
/
|
The root group of the specified file. |
| Group identifier |
/
|
The root group of the file containing the specified group. |
| Group identifier |
foo/bar |
The object bar in group foo in
the specified group. |
| File identifier |
.
|
The root group of the file. |
| Group identifier |
.
|
The specified group. |
| Other identifier |
.
|
The specified object. |
h5_crtgrpar.cgrpsexample.f90CreateGroupAR.java
H5Gcreate/h5gcreate_f creates a group at the
location specified by a location identifier and a name.
The location identifier can be a file identifier or a group identifier
and the name can be relative or absolute.
H5Gcreate/h5gcreate_f creates the group
MyGroup in the root group of the specified file.
H5Gcreate/h5gcreate_f creates the group
Group_A in the group MyGroup in the root group
of the specified file. Note that the parent group (MyGroup)
already exists.
H5Gcreate/h5gcreate_f creates the group
Group_B in the specified group.
Fig. 9.1 The Contents of groups.h5
(groupsf.h5 for FORTRAN)
groups.h5 in DDL
(for FORTRAN, the name in the first line is groupsf.h5)
HDF5 "groups.h5" {
GROUP "/" {
GROUP "MyGroup" {
GROUP "Group_A" {
}
GROUP "Group_B" {
}
}
}
}