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| HDF5 Last Updated on 2026-07-28 The HDF5 Field Guide

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HDF5 Lite APIs (H5LT,H5LD)

## Detailed Description

Functions used to simplify creating and manipulating datasets, attributes and other features (H5LT, H5LD)

The HDF5 Lite API consists of higher-level functions which do more operations per call than the basic HDF5 interface. The purpose is to wrap intuitive functions around certain sets of features in the existing APIs. It has the following sets of functions listed below.

Note
  Programming hints:
  To use any of these functions or subroutines, you must first include the relevant include file (C) or module (Fortran) in your application.
  The following line includes the HDF5 Lite package, H5LT, in C applications:
  #include "hdf5_hl.h"
  This line includes the H5LT module in Fortran applications:
  use h5lt
  h5lt
  This module contains Fortran interfaces for H5LT.
  Definition H5LTff_gen.F90:29

Dataset Functions Make dataset functions H5LTmake_dataset H5LTmake_dataset_char H5LTmake_dataset_short H5LTmake_dataset_int H5LTmake_dataset_long H5LTmake_dataset_float H5LTmake_dataset_double H5LTmake_dataset_string Read dataset functions H5LTread_dataset H5LTread_dataset_char H5LTread_dataset_short H5LTread_dataset_int H5LTread_dataset_long H5LTread_dataset_float H5LTread_dataset_double H5LTread_dataset_string Query dataset functions H5LTfind_dataset H5LTget_dataset_ndims H5LTget_dataset_info Dataset watch functions H5LDget_dset_dims H5LDget_dset_elmts H5LDget_dset_type_size | Attribute Functions Set attribute functions H5LTset_attribute_string H5LTset_attribute_char H5LTset_attribute_uchar H5LTset_attribute_short H5LTset_attribute_ushort H5LTset_attribute_int H5LTset_attribute_uint H5LTset_attribute_long H5LTset_attribute_long_long H5LTset_attribute_ulong H5LTset_attribute_ullong H5LTset_attribute_float H5LTset_attribute_double `H5LTset_attribute_f` (fortran ONLY) Get attribute functions H5LTget_attribute H5LTget_attribute_string H5LTget_attribute_char H5LTget_attribute_uchar H5LTget_attribute_short H5LTget_attribute_ushort H5LTget_attribute_int H5LTget_attribute_uint H5LTget_attribute_long H5LTget_attribute_long_long H5LTget_attribute_ulong H5LTget_attribute_ullong H5LTget_attribute_float H5LTget_attribute_double Query attribute functions H5LTfind_attribute H5LTget_attribute_info H5LTget_attribute_ndims | Datatype Functions Datatype translation functions H5LTtext_to_dtype H5LTdtype_to_text File image function Open file image function H5LTopen_file_image Path and object function Query path and object function H5LTpath_valid

## Namespaces
module | h5lt
| This module contains Fortran interfaces for H5LT.

## Functions
H5HL_DLL herr_t | H5LDget_dset_dims (hid_t did, hsize_t *cur_dims)
| Retrieves the current dimension sizes of a dataset.
H5HL_DLL herr_t | H5LDget_dset_elmts (hid_t did, const hsize_t *prev_dims, const hsize_t *cur_dims, const char *fields, void *buf)
| Retrieves selected data from the dataset.
H5HL_DLL size_t | H5LDget_dset_type_size (hid_t did, const char *fields)
| Returns the size in bytes of the dataset's datatype.
H5HL_DLL herr_t | H5LTdtype_to_text (hid_t dtype, char *str, H5LT_lang_t lang_type, size_t *len)
| Creates a text description of an HDF5 datatype.
H5HL_DLL herr_t | H5LTfind_attribute (hid_t loc_id, const char *name)
| Determines whether an attribute exists.
H5HL_DLL herr_t | H5LTfind_dataset (hid_t loc_id, const char *name)
| Determines whether a dataset exists.
H5HL_DLL herr_t | H5LTget_attribute (hid_t loc_id, const char *obj_name, const char *attr_name, hid_t mem_type_id, void *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_char (hid_t loc_id, const char *obj_name, const char *attr_name, char *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_double (hid_t loc_id, const char *obj_name, const char *attr_name, double *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_float (hid_t loc_id, const char *obj_name, const char *attr_name, float *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_info (hid_t loc_id, const char *obj_name, const char *attr_name, hsize_t *dims, H5T_class_t *type_class, size_t *type_size)
| Gets information about an attribute.
H5HL_DLL herr_t | H5LTget_attribute_int (hid_t loc_id, const char *obj_name, const char *attr_name, int *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_long (hid_t loc_id, const char *obj_name, const char *attr_name, long *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_long_long (hid_t loc_id, const char *obj_name, const char *attr_name, long long *data)
| Reads a long long attribute.
H5HL_DLL herr_t | H5LTget_attribute_ndims (hid_t loc_id, const char *obj_name, const char *attr_name, int *rank)
| Gets the dimensionality of an attribute.
H5HL_DLL herr_t | H5LTget_attribute_short (hid_t loc_id, const char *obj_name, const char *attr_name, short *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_string (hid_t loc_id, const char *obj_name, const char *attr_name, char *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_uchar (hid_t loc_id, const char *obj_name, const char *attr_name, unsigned char *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_uint (hid_t loc_id, const char *obj_name, const char *attr_name, unsigned int *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_ullong (hid_t loc_id, const char *obj_name, const char *attr_name, unsigned long long *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_ulong (hid_t loc_id, const char *obj_name, const char *attr_name, unsigned long *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_attribute_ushort (hid_t loc_id, const char *obj_name, const char *attr_name, unsigned short *data)
| Reads an attribute from disk.
H5HL_DLL herr_t | H5LTget_dataset_info (hid_t loc_id, const char *dset_name, hsize_t *dims, H5T_class_t *type_class, size_t *type_size)
| Retrieves information about a dataset.
H5HL_DLL herr_t | H5LTget_dataset_ndims (hid_t loc_id, const char *dset_name, int *rank)
| Gets the dimensionality of a dataset.
H5HL_DLL herr_t | H5LTmake_dataset (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, hid_t type_id, const void *buffer)
| Creates and writes a dataset of a type `type_id`.
H5HL_DLL herr_t | H5LTmake_dataset_char (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const char *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_double (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const double *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_float (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const float *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_int (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const int *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_long (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const long *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_short (hid_t loc_id, const char *dset_name, int rank, const hsize_t *dims, const short *buffer)
| Creates and writes a dataset.
H5HL_DLL herr_t | H5LTmake_dataset_string (hid_t loc_id, const char *dset_name, const char *buf)
| Creates and writes a dataset with string datatype.
H5HL_DLL hid_t | H5LTopen_file_image (void *buf_ptr, size_t buf_size, unsigned flags)
| Opens an HDF5 file image in memory.
H5HL_DLL htri_t | H5LTpath_valid (hid_t loc_id, const char *path, bool check_object_valid)
| Determines whether an HDF5 path is valid and, optionally, whether the path resolves to an HDF5 object.
H5HL_DLL herr_t | H5LTread_dataset (hid_t loc_id, const char *dset_name, hid_t type_id, void *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_char (hid_t loc_id, const char *dset_name, char *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_double (hid_t loc_id, const char *dset_name, double *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_float (hid_t loc_id, const char *dset_name, float *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_int (hid_t loc_id, const char *dset_name, int *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_long (hid_t loc_id, const char *dset_name, long *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_short (hid_t loc_id, const char *dset_name, short *buffer)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTread_dataset_string (hid_t loc_id, const char *dset_name, char *buf)
| Reads a dataset from disk.
H5HL_DLL herr_t | H5LTset_attribute_char (hid_t loc_id, const char *obj_name, const char *attr_name, const char *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_double (hid_t loc_id, const char *obj_name, const char *attr_name, const double *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_float (hid_t loc_id, const char *obj_name, const char *attr_name, const float *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_int (hid_t loc_id, const char *obj_name, const char *attr_name, const int *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_long (hid_t loc_id, const char *obj_name, const char *attr_name, const long *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_long_long (hid_t loc_id, const char *obj_name, const char *attr_name, const long long *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_short (hid_t loc_id, const char *obj_name, const char *attr_name, const short *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_string (hid_t loc_id, const char *obj_name, const char *attr_name, const char *attr_data)
| Creates and writes a string attribute.
H5HL_DLL herr_t | H5LTset_attribute_uchar (hid_t loc_id, const char *obj_name, const char *attr_name, const unsigned char *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_uint (hid_t loc_id, const char *obj_name, const char *attr_name, const unsigned int *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_ullong (hid_t loc_id, const char *obj_name, const char *attr_name, const unsigned long long *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_ulong (hid_t loc_id, const char *obj_name, const char *attr_name, const unsigned long *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL herr_t | H5LTset_attribute_ushort (hid_t loc_id, const char *obj_name, const char *attr_name, const unsigned short *buffer, size_t size)
| Creates and writes an attribute.
H5HL_DLL hid_t | H5LTtext_to_dtype (const char *text, H5LT_lang_t lang_type)
| Creates an HDF5 datatype given a text description.

## Function Documentation

## ◆ H5LDget_dset_dims()

H5HL_DLL herr_t H5LDget_dset_dims | ( | hid_t | did,
|  | hsize_t * | cur_dims )

Retrieves the current dimension sizes of a dataset.

Parameters

  [in] | did | The dataset identifier
  [out] | cur_dims | The current dimension sizes of the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LDget_dset_dims() retrieves the current dimension sizes for the dataset `did` through the parameter `cur_dims`. It will return failure if `cur_dims` is NULL.

Note
  See Also:
  Dataset Watch functions (used with h5watch):
  - H5LDget_dset_dims()
  - H5LDget_dset_elmts()
  - H5LDget_dset_type_size()

Example:
  See the example code in H5LDget_dset_elmts() for usage of this routine.

Since
  1.10.0

## ◆ H5LDget_dset_elmts()

H5HL_DLL herr_t H5LDget_dset_elmts | ( | hid_t | did,
|  | const hsize_t * | prev_dims,
|  | const hsize_t * | cur_dims,
|  | const char * | fields,
|  | void * | buf )

Retrieves selected data from the dataset.

Parameters

  [in] | did | The dataset identifier
  [in] | prev_dims | The previous dimension size of the dataset
  [in] | cur_dims | The current dimension sizes of the dataset
  [in] | fields | A string containing a comma-separated list of fields for a compound datatype
  [out] | buf | Buffer for storing data retrieved from the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LDget_dset_dims() retrieves selected data of the dataset `did` and stores the data in the parameter `buf`. The difference between the parameters `prev_dims` and `cur_dims` indicates the dimension sizes of the data to be selected from the dataset. Note that `cur_dims` must have at least one dimension whose size is greater than the corresponding dimension in `prev_dims`. Users can determine the size of buf by multiplying the datatype size of the dataset by the number of selected elements.

If the parameter `fields` is NULL, this routine returns data for the selected elements of the dataset. If `fields` is not NULL and the dataset has a compound datatype, `fields` is a string containing a comma-separated list of fields. Each name in `fields` specifies a field in the compound datatype, and this routine returns data of the selected fields for the dataset's selected elements. Note that ’,’ is the separator for the fields of a compound datatype while ’.’ is the separator for a nested field. Use backslash to escape characters in field names that conflict with these two separators.

Note
  See Also:
  Dataset Watch functions (used with h5watch):
  - H5LDget_dset_dims()
  - H5LDget_dset_elmts()
  - H5LDget_dset_type_size()

Examples:

For the first example, `DSET1` is a two-dimensional chunked dataset with atomic type defined below:

DATASET "DSET1" {DATATYPE H5T_STD_I32LE DATASPACE SIMPLE{(4, 13) / (60, 100)} : : }

The following coding sample illustrates the reading of data elements appended to the dataset `DSET1:`

/* open the HDF5 file */
fid = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);
/* open the dataset */
did = H5Dopen2(fid, "DSET1", H5P_DEFAULT);
:
:
/* define hsize_t dims[2]; */
/* define hsize_t new_dims[2]; */
/* get the dataset's current dimension sizes */
H5LDget_dset_dims(did, dims);
/* extend the dataset by 2 */
new_dims[0] = dims[0] + 2;
new_dims[1] = dims[1] + 2;
H5Dset_extent(did, new_dims)
/* write data to the extended dataset */
: :
/* get the size of the dataset's data type */
type_size = H5LDget_dset_type_size(did, NULL);
:
:
/* allocate buffer for storing selected data elements from the dataset */
/* calculate # of selected elements from dims & new_dims */
/* buffer size = type_size * number of selected elements */
:
:
/* read the selected elements from the dataset into buf */
H5LDget_dset_elmts(did, dims, new_dims, NULL, buf);
:
:
H5Dclose(did);
H5Fclose(fid);

The output buffer will contain data elements selected from `DSET1` as follows:

data for elements (0, 13), (0, 14)
data for elements (1, 13), (1, 14)
data for elements (2, 13), (2, 14)
data for elements (3, 13), (3, 14)
data for elements (4, 0), (4, 1), (4, 2)......................(4, 13), (4, 14)
data for elements (5, 0), (5, 1), (5, 2)......................(5, 13), (5, 14)

For the second example, DSET2 is a one-dimensional chunked dataset with compound type defined below:

DATASET "DSET2" {
DATATYPE H5T_COMPOUND {
H5T_STD_I32LE "a";
H5T_STD_I32LE "b";
H5T_ARRAY
{
[4] H5T_STD_I32LE
}
"c";
H5T_STD_I32LE "d";
H5T_STD_I32LE "e";
H5T_COMPOUND
{
H5T_STD_I32LE "a";
H5T_STD_I32LE "b";
H5T_ARRAY
{
[4] H5T_STD_I32LE
}
"c";
H5T_STD_I32LE "d";
H5T_STD_I32LE "e";
}
"s2";
}
DATASPACE SIMPLE
{
(5) / (5)
}
::
}

The following coding sample illustrates the reading of data elements appended to the dataset `DSET2` with compound datatype. This example selects only 2 fields: the fourth field `d` and a subfield of the sixth field `s2.c:`

/* open the HDF5 file */
fid = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);
/* open the dataset */
did = H5Dopen2(fid, "DSET2", H5P_DEFAULT);
/* define hsize_t dims[1]; */
/* define hsize_t new_dims[1]; */
:
:
/* get the dataset's current dimension size */
H5LDget_dset_dims(did, dims);
/* extend the dataset by 2 */
new_dims[0] = dims[0] + 2;
H5Dset_extent(did, new_dims);
:
:
/* write data to the extended part of the dataset */
:
:
/* #define fields "d,s2.c" */
/* get the size of the dataset's data type for the selected fields */
type_size = H5LDget_dset_type_size(did, fields);
:
:
/* allocate buffer for storing selected data elements from the dataset */
/* calculate # of selected elements from dims & new_dims */
/* buffer size = type_size * number of selected elements */
:
:
/* read the selected elements from the dataset into buf */
H5LD_get_dset_elmts(did, dims, new_dims, fields, buf);
:
:
H5Dclose(did);
H5Fclose(fid);

The output buffer will contain data for `d` and `s2.c` selected from `DSET2` as follows:

Data for element (5): integer value for "d", 4 integer values for array "s2.c"
Data for element (6): integer value for "d", 4 integer values for array "s2.c"

Since
  1.10.0

## ◆ H5LDget_dset_type_size()

H5HL_DLL size_t H5LDget_dset_type_size | ( | hid_t | did,
|  | const char * | fields )

Returns the size in bytes of the dataset's datatype.

Parameters

  [in] | did | The dataset identifier
  [in] | fields | The pointer to a comma-separated list of fields for a compound datatype

Returns
  If successful, returns the size in bytes of the dataset's datatype. Otherwise, returns 0.

H5LDget_dset_type_size() allows the user to find out the datatype size for the dataset associated with `did`. If the parameter `fields` is NULL, this routine just returns the size of the dataset's datatype. If the dataset has a compound datatype and `fields` is non-NULL, this routine returns the size of the datatype(s) for the selected fields specified in `fields`. Note that ’,’ is the separator for the fields of a compound datatype while ’.’ (dot) is the separator for a nested field. Use a backslash ( \ ) to escape characters in field names that conflict with these two separators.

Note
  See Also:
  Dataset Watch functions (used with h5watch):
  - H5LDget_dset_dims()
  - H5LDget_dset_elmts()
  - H5LDget_dset_type_size()

Example:
  See the example code in H5LDget_dset_elmts() for usage of this routine.

Since
  1.10.0

## ◆ H5LTdtype_to_text()

H5HL_DLL herr_t H5LTdtype_to_text | ( | hid_t | dtype,
|  | char * | str,
|  | H5LT_lang_t | lang_type,
|  | size_t * | len )

Creates a text description of an HDF5 datatype.

Parameters

  [in] | dtype | Identifier of the datatype to be converted
  [out] | str | Buffer for the text description of the datatype
  [in] | lang_type | The language used to describe the datatype. The currently supported language is H5LT_DDL.
  [out] | len | The size of buffer needed to store the text description

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

Given an HDF5 datatype identifier, this function creates a description of this datatype in `lang_type` language format. A preliminary H5LTdtype_to_text() call can be made to determine the size of the buffer needed with a NULL passed in for `str`. This value is returned as `len`. That value can then be assigned to len for a second H5Ttype_to_text() call, which will retrieve the actual text description for the datatype.

If `len` is not big enough for the description, the text description will be truncated to fit in the buffer.

Currently only DDL (H5LT_DDL) is supported for `lang_type`. The complete DDL definition of HDF5 data types can be found in the Specifications chapter of the HDF5 User's Guide.

Example
  An example of DDL definition of `enum` type is shown as follows.
  “H5T_ENUM
  {
  H5T_NATIVE_INT;
  “Bob” 0;
  “Elena” 1;
  “Quincey” 2;
  “Frank” 3;
  }
  ”

## ◆ H5LTfind_attribute()

H5HL_DLL herr_t H5LTfind_attribute | ( | hid_t | loc_id,
|  | const char * | name )

Determines whether an attribute exists.

Parameters

  [in] | loc_id | Identifier of the object to which the attribute is expected to be attached
  [in] | name | Attribute name

Returns
  Returns zero (false), a positive (true) or a negative (failure) value.

H5LTfind_attribute() determines whether an attribute named `name` exists attached to the object specified by `loc_id`.

`loc_id` must be an object identifier and `name` must specify an attribute that is expected to be attached to that object.

## ◆ H5LTfind_dataset()

H5HL_DLL herr_t H5LTfind_dataset | ( | hid_t | loc_id,
|  | const char * | name )

Determines whether a dataset exists.

Parameters

  [in] | loc_id | Identifier of the group containing the dataset
  [in] | name | Dataset name

Returns
  Returns zero (false), a positive (true) or a negative (failure) value.

H5LTfind_dataset() determines whether a dataset named `name` exists in the group specified by `loc_id`.

`loc_id` must be a group identifier and `name` must specify a dataset that is a member of that group.

## ◆ H5LTget_attribute()

H5HL_DLL herr_t H5LTget_attribute | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | hid_t | mem_type_id,
|  | void * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [in] | mem_type_id | Identifier of the memory datatype
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute() reads an attribute named `attr_name` with the memory type `mem_type_id`.

## ◆ H5LTget_attribute_char()

H5HL_DLL herr_t H5LTget_attribute_char | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | char * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_char() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The datatype of the attribute is H5T_NATIVE_CHAR.

## ◆ H5LTget_attribute_double()

H5HL_DLL herr_t H5LTget_attribute_double | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | double * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_double() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_DOUBLE.

## ◆ H5LTget_attribute_float()

H5HL_DLL herr_t H5LTget_attribute_float | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | float * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_float() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_FLOAT.

## ◆ H5LTget_attribute_info()

H5HL_DLL herr_t H5LTget_attribute_info | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | hsize_t * | dims,
|  | H5T_class_t * | type_class,
|  | size_t * | type_size )

Gets information about an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | dims | The dimensions of the attribute
  [out] | type_class | The class identifier. H5T_class_t is defined in H5Tpublic.h. For a list of valid class types see: H5Tget_class().
  [out] | type_size | The size of the datatype in bytes

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_info() gets information about an attribute named `attr_name` attached to the object specified by the name `obj_name`.

Example
  H5T_class_t type_class;
  size_t type_size;
  hsize_t dims[0];
  ... status = H5LTget_attribute_info(file_id, "/", STRNAME, dims, &type_class, &type_size);
  if (type_class == H5T_STRING) {
  printf("Attribute is a string.\n");
  printf("String size: %i\n", type_size);

## ◆ H5LTget_attribute_int()

H5HL_DLL herr_t H5LTget_attribute_int | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | int * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_int() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_INT.

## ◆ H5LTget_attribute_long()

H5HL_DLL herr_t H5LTget_attribute_long | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | long * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_long() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_LONG.

## ◆ H5LTget_attribute_long_long()

H5HL_DLL herr_t H5LTget_attribute_long_long | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | long long * | data )

Reads a long long attribute.

Parameters

  [in] | loc_id | Location of the object to which the attribute is attached
  [in] | obj_name | That object's name
  [in] | attr_name | Attribute name
  [out] | data | Attribute value

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_long_long() reads the attribute specified by `loc_id` and `obj_name`.

## ◆ H5LTget_attribute_ndims()

H5HL_DLL herr_t H5LTget_attribute_ndims | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | int * | rank )

Gets the dimensionality of an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | rank | The dimensionality of the attribute

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_ndims() gets the dimensionality of an attribute named `attr_name` that is attached to the object specified by the name `obj_name`.

## ◆ H5LTget_attribute_short()

H5HL_DLL herr_t H5LTget_attribute_short | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | short * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_short() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_SHORT

## ◆ H5LTget_attribute_string()

H5HL_DLL herr_t H5LTget_attribute_string | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | char * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_string() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The datatype is a string.

Version
  1.8.9 The content of the buffer returned by the Fortran subroutine has changed in this release:
  If the returned buffer requires padding, h5ltget_attribute_string_f() now employs space padding; this buffer was previously returned with a C NULL terminator.

## ◆ H5LTget_attribute_uchar()

H5HL_DLL herr_t H5LTget_attribute_uchar | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | unsigned char * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_uchar() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_UCHAR

## ◆ H5LTget_attribute_uint()

H5HL_DLL herr_t H5LTget_attribute_uint | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | unsigned int * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_uint() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_INT.

## ◆ H5LTget_attribute_ullong()

H5HL_DLL herr_t H5LTget_attribute_ullong | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | unsigned long long * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_ullong() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_ULLONG.

## ◆ H5LTget_attribute_ulong()

H5HL_DLL herr_t H5LTget_attribute_ulong | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | unsigned long * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_ulong() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_ULONG.

## ◆ H5LTget_attribute_ushort()

H5HL_DLL herr_t H5LTget_attribute_ushort | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | unsigned short * | data )

Reads an attribute from disk.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to read the attribute from
  [in] | obj_name | The name of the object that the attribute is attached to
  [in] | attr_name | The attribute name
  [out] | data | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_attribute_ushort() reads an attribute named `attr_name` that is attached to the object specified by the name `obj_name`. The HDF5 datatype of the attribute is H5T_NATIVE_USHORT.

## ◆ H5LTget_dataset_info()

H5HL_DLL herr_t H5LTget_dataset_info | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | hsize_t * | dims,
|  | H5T_class_t * | type_class,
|  | size_t * | type_size )

Retrieves information about a dataset.

Parameters

  [in] | loc_id | Identifier of the object to locate the dataset within
  [in] | dset_name | The dataset name
  [out] | dims | The dimensions of the dataset
  [out] | type_class | The class identifier. H5T_class_t is defined in H5Tpublic.h. See H5Tget_class() for a list of class types.
  [out] | type_size | The size of the datatype in bytes

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_dataset_info() retrieves information about a dataset named `dset_name` attached to the object `loc_id`.

## ◆ H5LTget_dataset_ndims()

H5HL_DLL herr_t H5LTget_dataset_ndims | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int * | rank )

Gets the dimensionality of a dataset.

Parameters

  [in] | loc_id | Identifier of the object to locate the dataset within
  [in] | dset_name | The dataset name
  [out] | rank | The dimensionality of the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTget_dataset_ndims() gets the dimensionality of a dataset named `dset_name` exists attached to the object `loc_id`.

## ◆ H5LTmake_dataset()

H5HL_DLL herr_t H5LTmake_dataset | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | hid_t | type_id,
|  | const void * | buffer )

Creates and writes a dataset of a type `type_id`.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | type_id | Identifier of the datatype to use when creating the dataset
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The parameter `type_id` can be any valid HDF5 Prdefined Native Datatypes; For example, setting `type_id` to H5T_NATIVE_INT will result in a dataset of signed integer datatype.

Version
  1.10.0 Fortran 2003 subroutine added to accept a C address of the data buffer.
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTmake_dataset_char()

H5HL_DLL herr_t H5LTmake_dataset_char | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const char * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_char() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be character, H5T_NATIVE_CHAR.

## ◆ H5LTmake_dataset_double()

H5HL_DLL herr_t H5LTmake_dataset_double | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const double * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_double() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be native floating-point double, H5T_NATIVE_DOUBLE.

Version
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTmake_dataset_float()

H5HL_DLL herr_t H5LTmake_dataset_float | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const float * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_float() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be native floating point, H5T_NATIVE_FLOAT.

Version
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTmake_dataset_int()

H5HL_DLL herr_t H5LTmake_dataset_int | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const int * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_int() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be native signed integer, H5T_NATIVE_INT.

Version
  Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTmake_dataset_long()

H5HL_DLL herr_t H5LTmake_dataset_long | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const long * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_long() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be long signed integer, H5T_NATIVE_LONG.

## ◆ H5LTmake_dataset_short()

H5HL_DLL herr_t H5LTmake_dataset_short | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int | rank,
|  | const hsize_t * | dims,
|  | const short * | buffer )

Creates and writes a dataset.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The Name of the dataset to create
  [in] | rank | Number of dimensions of dataspace
  [in] | dims | An array of the size of each dimension
  [in] | buffer | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_short() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be short signed integer, H5T_NATIVE_SHORT.

## ◆ H5LTmake_dataset_string()

H5HL_DLL herr_t H5LTmake_dataset_string | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | const char * | buf )

Creates and writes a dataset with string datatype.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to create
  [in] | buf | Buffer with data to be written to the dataset

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTmake_dataset_string() creates and writes a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

The dataset's datatype will be C string, H5T_C_S1.

## ◆ H5LTopen_file_image()

H5HL_DLL hid_t H5LTopen_file_image | ( | void * | buf_ptr,
|  | size_t | buf_size,
|  | unsigned | flags )

Opens an HDF5 file image in memory.

Parameters

  [in] | buf_ptr | A pointer to the supplied initial image
  [in] | buf_size | Size of the supplied buffer
  [in] | flags | Flags specifying whether to open the image read-only or read/write, whether HDF5 is to take control of the buffer, and instruction regarding releasing the buffer.

Returns
  Returns a file identifier if successful; otherwise returns a negative value.

Warning
  Failure Modes:
  H5LTopen_file_image() will fail if either `buf_ptr` is NULL or `buf_size` equals 0 (zero).

H5LTopen_file_image() opens the HDF5 file image that is located in system memory at the address indicated by `buf_ptr` of size `buf_size`. H5LTopen_file_image() opens a file image with the Core driver, H5FD_CORE.

A value of NULL for `buf_ptr` is invalid and will cause the function to fail.

A value of 0 for `buf_size` is invalid and will cause the function to fail.

The flags passed in `flags` specify whether to open the image read-only or read/write, whether HDF5 is to take control of the buffer, and instruction regarding releasing the buffer. Valid values are:

- H5LT_FILE_IMAGE_OPEN_RW
  - Specifies opening the file image in read/write mode.
  - Default without this flag: File image will be opened read-only.
- H5LT_FILE_IMAGE_DONT_COPY
  - Specifies to not copy the provided file image buffer; the buffer will be used directly. HDF5 will release the file image when finished.
  - Default without this flag: Copy the file image buffer and open the copied file image.
- H5LT_FILE_IMAGE_DONT_RELEASE
  - Specifies that HDF5 is not to release the buffer when the file opened with H5LTopen_file_image() is closed; releasing the buffer will be left to the application.
  - Default without this flag: HDF5 will automatically release the file image buffer after the file image is closed. This flag is valid only when used with H5LT_FILE_IMAGE_DONT_COPY.

Note
  Motivation:
  H5LTopen_file_image() and other elements of HDF5 are used to load an image of an HDF5 file into system memory and open that image as a regular HDF5 file. An application can then use the file without the overhead of disk I/O.
  Recommended Reading:
  This function is part of the file image operations feature set. It is highly recommended to study the guide HDF5 File Image before using this feature set.
  See the “See Also” section below for links to other elements of HDF5 file image operations.

Todo
  There is no "See Also" section???

Since
  1.8.9

## ◆ H5LTpath_valid()

H5HL_DLL htri_t H5LTpath_valid | ( | hid_t | loc_id,
|  | const char * | path,
|  | bool | check_object_valid )

Determines whether an HDF5 path is valid and, optionally, whether the path resolves to an HDF5 object.

Parameters

  [in] | loc_id | Identifier of an object in the file
  [in] | path | The path to the object to check; links in `path` may be of any type.
  [in] | check_object_valid | If TRUE, determine whether the final component of `path` resolves to an object; if FALSE, do not check.

Returns
  Upon success:
  If `check_object_valid` is set to `FALSE:`
  Returns `TRUE` if the path is valid; otherwise returns `FALSE`.
  If `check_object_valid` is set to `TRUE:`
  Returns `TRUE` if the path is valid and resolves to an HDF5 object; otherwise returns `FALSE`.
  Upon error, returns a negative value.

H5LTpath_valid() checks the validity of `path` relative to the identifier of an object, `loc_id`. Optionally, `check_object_valid` can be set to determine whether the final component of `path` resolves to an HDF5 object; if not, the final component is a dangling link.

The meaning of the function's return value depends on the value of `check_object_valid:`

If `check_object_valid` is set to `FALSE`, H5LTpath_valid() will check all links in `path` to verify that they exist. If all the links in `path` exist, the function will return `TRUE`; otherwise the function will return `FALSE`.

If `check_object_valid` is set to `TRUE`, H5LTpath_valid() will first check the links in `path`, as described above. If all the links exist, `check_object_valid` will then determine whether the final component of `path` resolves to an actual HDF5 object. H5LTpath_valid() will return `TRUE` if all the links in `path` exist and the final component resolves to an actual object; otherwise, it will return `FALSE`.

`path` can be any one of the following:

- An absolute path, which starts with a slash (`/`) indicating the file's root group, followed by the members
- A relative path with respect to `loc_id`
- A dot (``.), if `loc_id` is the object identifier for the object itself.

If `path` is an absolute path, then `loc_id` can be an identifier for any object in the file as it is used only to identify the file. If `path` is a relative path, then `loc_id` must be a file or a group identifier.

Note
  Note on Behavior Change: The behavior of H5LTpath_valid() was changed in the 1.10.0 release in the case where the root group, “/”, is the value of path. This change is described below:
  - Let `loc_id` denote a valid HDF5 file identifier, and let `check_object_valid` be set to true or false. A call to H5LTpath_valid() with arguments `loc_id`, “/”, and `check_object_valid` returns a positive value; in other words, H5LTpath_valid(loc_id, "/", check_object_valid) returns a positive value. In HDF5 version 1.8.16, this function returns 0.
  - Let ‘root’ denote a valid HDF5 group identifier that refers to the root group of an HDF5 file, and let `check_object_valid` be set to true or false. A call to H5LTpath_valid() with arguments ‘root’, “/”, and `check_object_valid` returns a positive value; in other words, H5LTpath_valid(root, "/", check_object_valid) returns a positive value. In HDF5 version 1.8.16, this function returns 0.

Version
  1.10.0 Function behavior changed in this release. See the “Note on Behavior Change” section above.

## ◆ H5LTread_dataset()

H5HL_DLL herr_t H5LTread_dataset | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | hid_t | type_id,
|  | void * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [in] | type_id | Identifier of the datatype to use when reading the dataset
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`.

Version
  1.10.0 Fortran 2003 subroutine added to accept a C address of the data buffer.
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTread_dataset_char()

H5HL_DLL herr_t H5LTread_dataset_char | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | char * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_char() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_CHAR.

## ◆ H5LTread_dataset_double()

H5HL_DLL herr_t H5LTread_dataset_double | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | double * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_double() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_DOUBLE.

Version
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTread_dataset_float()

H5HL_DLL herr_t H5LTread_dataset_float | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | float * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_float() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_FLOAT.

Version
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTread_dataset_int()

H5HL_DLL herr_t H5LTread_dataset_int | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | int * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_int() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_INT.

Version
  1.8.7 Fortran subroutine modified in this release to accommodate arrays with more than three dimensions.

## ◆ H5LTread_dataset_long()

H5HL_DLL herr_t H5LTread_dataset_long | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | long * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_long() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_LONG.

## ◆ H5LTread_dataset_short()

H5HL_DLL herr_t H5LTread_dataset_short | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | short * | buffer )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buffer | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_short() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_NATIVE_SHORT.

## ◆ H5LTread_dataset_string()

H5HL_DLL herr_t H5LTread_dataset_string | ( | hid_t | loc_id,
|  | const char * | dset_name,
|  | char * | buf )

Reads a dataset from disk.

Parameters

  [in] | loc_id | Location identifier. The identifier may be that of a file or group.
  [in] | dset_name | The name of the dataset to read
  [out] | buf | Buffer with data

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTread_dataset_string() reads a dataset named `dset_name` attached to the object specified by the identifier `loc_id`. The HDF5 datatype is H5T_C_S1.

## ◆ H5LTset_attribute_char()

H5HL_DLL herr_t H5LTset_attribute_char | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const char * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_char() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_CHAR.

## ◆ H5LTset_attribute_double()

H5HL_DLL herr_t H5LTset_attribute_double | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const double * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_double() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_DOUBLE.

## ◆ H5LTset_attribute_float()

H5HL_DLL herr_t H5LTset_attribute_float | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const float * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_float() creates and writes a numerical floating point attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_FLOAT.

## ◆ H5LTset_attribute_int()

H5HL_DLL herr_t H5LTset_attribute_int | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const int * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_int() creates and writes a numerical integer attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_INT.

## ◆ H5LTset_attribute_long()

H5HL_DLL herr_t H5LTset_attribute_long | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const long * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_long() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_LONG.

## ◆ H5LTset_attribute_long_long()

H5HL_DLL herr_t H5LTset_attribute_long_long | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const long long * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Location of the object to which the attribute is to be attached
  [in] | obj_name | That object's name
  [in] | attr_name | Attribute name
  [in] | buffer | Attribute value
  [in] | size | Attribute size

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_long_long() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`.

The attribute has a dimensionality of 1 and its HDF5 datatype is H5T_NATIVE_LLONG.

## ◆ H5LTset_attribute_short()

H5HL_DLL herr_t H5LTset_attribute_short | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const short * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_short() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_SHORT.

## ◆ H5LTset_attribute_string()

H5HL_DLL herr_t H5LTset_attribute_string | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const char * | attr_data )

Creates and writes a string attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | attr_data | Buffer with data to be written to the attribute

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_string() creates and writes a string attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. If the attribute already exists, it is overwritten.

## ◆ H5LTset_attribute_uchar()

H5HL_DLL herr_t H5LTset_attribute_uchar | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const unsigned char * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_uchar() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_UCHAR.

## ◆ H5LTset_attribute_uint()

H5HL_DLL herr_t H5LTset_attribute_uint | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const unsigned int * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_uint() creates and writes a numerical integer attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_UINT.

## ◆ H5LTset_attribute_ullong()

H5HL_DLL herr_t H5LTset_attribute_ullong | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const unsigned long long * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Location of the object to which the attribute is to be attached
  [in] | obj_name | That object's name
  [in] | attr_name | Attribute name
  [in] | buffer | Attribute value
  [in] | size | Attribute size

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_ullong() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`.

The attribute has a dimensionality of 1 and its HDF5 datatype is H5T_NATIVE_ULLONG.

## ◆ H5LTset_attribute_ulong()

H5HL_DLL herr_t H5LTset_attribute_ulong | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const unsigned long * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_ulong() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_ULONG.

## ◆ H5LTset_attribute_ushort()

H5HL_DLL herr_t H5LTset_attribute_ushort | ( | hid_t | loc_id,
|  | const char * | obj_name,
|  | const char * | attr_name,
|  | const unsigned short * | buffer,
|  | size_t | size )

Creates and writes an attribute.

Parameters

  [in] | loc_id | Identifier of the object (dataset or group) to create the attribute within
  [in] | obj_name | The name of the object to attach the attribute
  [in] | attr_name | The attribute name
  [in] | buffer | Buffer with data to be written to the attribute
  [in] | size | The size of the 1D array (one in the case of a scalar attribute). This value is used by H5Screate_simple() to create the dataspace.

Returns
  Returns a non-negative value if successful; otherwise, returns a negative value.

H5LTset_attribute_ushort() creates and writes a numerical attribute named `attr_name` and attaches it to the object specified by the name `obj_name`. The attribute has a dimensionality of 1. The HDF5 datatype of the attribute is H5T_NATIVE_USHORT.

## ◆ H5LTtext_to_dtype()

H5HL_DLL hid_t H5LTtext_to_dtype | ( | const char * | text,
|  | H5LT_lang_t | lang_type )

Creates an HDF5 datatype given a text description.

Parameters

  [in] | text | A character string containing a DDL definition of the datatype to be created
  [in] | lang_type | The language used to describe the datatype. The only currently supported language is H5LT_DDL.

Returns
  Returns the datatype identifier(non-negative) if successful; otherwise returns a negative value.

Given a text description of a datatype, this function creates an HDF5 datatype and returns the datatype identifier. The text description of the datatype has to comply with the `lang_type` definition of HDF5 datatypes. Currently, only the DDL(H5LT_DDL) is supported. The complete DDL definition of HDF5 datatypes can be found in the Specifications chapter of the HDF5 User's Guide.

Example
  An example of DDL definition of `enum` type is shown as follows.
  “H5T_ENUM
  {
  H5T_NATIVE_INT;
  “Bob” 0;
  “Elena” 1;
  “Quincey” 2;
  “Frank” 3;
  }
  ”