- Created by Mike McGreevy, last modified by Barbara Jones on Oct 25, 2019
H5T_GET_NATIVE_TYPE
Returns the native datatype identifier of a specified datatype
Procedure:
H5T_GET_NATIVE_TYPE (dtype_id, direction)
Signature:
hid_t H5Tget_native_type( hid_t dtype_id, H5T_direction_t direction )
SUBROUTINE h5tget_native_type_f(dtype_id, direction, native_dtype_id, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: dtype_id
! Datatype identifier
INTEGER, INTENT(IN) :: direction ! Direction of search:
! H5T_DIR_ASCEND_F = 1 in inscendent order
! H5T_DIR_DESCEND_F= 2 in descendent order
INTEGER(HID_T), INTENT(OUT) :: native_dtype_id
! The native datatype identifier
INTEGER, INTENT(OUT) :: hdferr ! Error code:
! 0 on success and -1 on failure
END SUBROUTINE h5tget_native_type_f
Parameters:
hid_t dtype_id | IN: Datatype identifier for the dataset datatype |
H5T_direction_t direction | IN: Direction of search |
Description:
H5T_GET_NATIVE_TYPE returns the equivalent native datatype identifier (or handle) for the datatype specified in dtype_id.
H5T_GET_NATIVE_TYPE is designed primarily to facilitate use of the H5D_READ function, for which users otherwise must undertake a multi-step process to determine the native datatype of a dataset prior to reading it into memory. This function can be used for the following purposes:
- To determine the native datatype of an atomic datatype
- To determine the base datatype of an array, enumerated, or variable-length datatype
- To determine the native atomic datatypes of the individual components of a compound datatype
For example, if dtype_id is a compound datatype, the returned datatype identifier will be for a similar compound datatype with each element converted to the corresponding native datatype; nested compound datatypes will be unwound. If dtype_id is an array, the returned datatype identifier will be for the native datatype of a single array element.
H5T_GET_NATIVE_TYPE selects the first matching native datatype from the following list:
H5T_NATIVE_CHAR
H5T_NATIVE_SHORT
H5T_NATIVE_INT
H5T_NATIVE_LONG
H5T_NATIVE_LLONG
H5T_NATIVE_UCHAR
H5T_NATIVE_USHORT
H5T_NATIVE_UINT
H5T_NATIVE_ULONG
H5T_NATIVE_ULLONG
H5T_NATIVE_FLOAT
H5T_NATIVE_DOUBLE
H5T_NATIVE_LDOUBLE
H5T_NATIVE_B8
H5T_NATIVE_B16
H5T_NATIVE_B32
H5T_NATIVE_B64The direction parameter indicates the order in which the library searches for a native datatype match. Valid values for direction are as follows:
H5T_DIR_ASCEND | Searches the above list in ascending size of the datatype, i.e., from top to bottom. (Default) |
H5T_DIR_DESCEND | Searches the above list in descending size of the datatype, i.e., from bottom to top. |
H5T_GET_NATIVE_TYPE is designed primarily for use with integer, floating point, and bitfield datatypes. String, time, opaque, and reference datatypes are returned as a copy of dtype_id. See above for compound, array, enumerated, and variable-length datatypes.
The identifier returned by H5T_GET_NATIVE_TYPE should eventually be closed by calling H5T_CLOSE to release resources.
Datatype Identifiers
Please note that a datatype is actually an object identifier or handle returned from opening the datatype. It is not persistent and its value can be different from one HDF5 session to the next.
H5T_EQUAL can be used to compare datatypes.
HDF5 High Level APIs that may also be of interest are:
- H5LT_DTYPE_TO_TEXT creates a text description of a datatype.
- H5LT_TEXT_TO_DTYPE creates an HDF5 datatype given a text description.
Returns:
Returns the native datatype identifier (or handle) for the specified dataset datatype if successful; otherwise returns a negative value.
Example:
Coming Soon!
History:
| Release | Change |
|---|---|
| 1.6.0 | Function introduced in this release. |
--- Last Modified: October 25, 2019 | 08:41 AM