H5Lexists(
hid_t loc_id,
const char *name,
hid_t lapl_id
)
H5Lexists allows an application to determine whether
the link name exists in
the group or file specified with loc_id.
The link may be of any type;
only the presence of a link with that name is checked.
Note that H5Lexists verifies only that the target
link exists.
If name includes either a relative path or
an absloute path to the target link, intermediate steps along the
path must be verified before the existence of the target link
can be safely checked.
If the path is not verified and an intermediate element of the path
does not exist, H5Lexists will fail.
The example in the next paragraph illustrates one step-by-step
method for verifying the existence of a link with a relative
or absolute path.
Example: Use the following steps to verify the existence
of the link datasetD
in the group group1/group2/softlink_to_group3/,
where group1 is a member of
the group specified by loc_id:
H5Lexists to verify that
group1 exists.
group1 exists,
use H5Lexists again, this time
with name set to group1/group2,
to verify thatgroup2 exists.
group2 exists,
use H5Lexists with name
set to group1/group2/softlink_to_group3
to verify that softlink_to_group3 exists.
softlink_to_group3 exists,
you can now safely use H5Lexists
with name set to
group1/group2/softlink_to_group3/datasetD
to verify that the target link, datasetD, exists.
If the link to be verified is specified with an absolute path,
the same approach should be used, but starting with the
first link in the file’s root group.
For instance, if datasetD were in
/group1/group2/softlink_to_group3, the first call to
H5Lexists would have name set to
/group1.
Note that this is an outline and does not include all necessary details. Depending on circumstances, for example, you may need to verify that an intermediate link points to a group and that a soft link points to an existing target.
hid_t loc_id
|
IN: Identifier of the file or group to query. |
const char *name
|
IN: The name of the link to check. |
hid_t lapl_id
|
IN: Link access property list identifier. |
TRUE or FALSE if successful;
otherwise returns a negative value.
H5Lexists checks the existence of only the final
element in a relative or absolute path; it does not check
any other path elements.
The function will therefore fail when both of the following
conditions exist:
name is not local to the group specified
by loc_id
or, if loc_id is something other than a
group identifier, name is not local to
the root group.
name, except the target link, does not exist.
SUBROUTINE h5lexists_f(loc_id, name, link_exists, hdferr, lapl_id)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: loc_id ! Identifier of file or group to query.
CHARACTER(LEN=*), INTENT(IN) :: name ! Link name to check.
LOGICAL, INTENT(OUT) :: link_exists ! .TRUE. if exists, .FALSE. otherwise
INTEGER, INTENT(OUT) :: hdferr ! Error code:
! 0 on success and -1 on failure
INTEGER(HID_T), OPTIONAL, INTENT(IN) :: lapl_id
! Link access property list identifier.
END SUBROUTINE h5lexists_f
| Release | C |
| 1.8.0 | Function introduced in this release. |