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/************************************************************
This example shows how to read and write opaque datatypes
to a dataset. The program first writes opaque data to a
dataset with a dataspace of DIM0, then closes the file.
Next, it reopens the file, reads back the data, and
outputs it to the screen.
************************************************************/
#include "hdf5.h"
#include <stdio.h>
#include <stdlib.h>
#define FILE "h5ex_t_opaque.h5"
#define DATASET "DS1"
#define DIM0 4
#define LEN 7
int
main(void)
{
hid_t file, space, dtype, dset; /* Handles */
herr_t status;
hsize_t dims[1] = {DIM0};
size_t len;
char wdata[DIM0 * LEN], /* Write buffer */
*rdata, /* Read buffer */
str[LEN] = "OPAQUE", *tag;
int ndims;
hsize_t i, j;
/*
* Initialize data.
*/
for (i = 0; i < DIM0; i++) {
for (j = 0; j < LEN - 1; j++)
wdata[j + i * LEN] = str[j];
wdata[LEN - 1 + i * LEN] = (char)i + '0';
}
/*
* Create a new file using the default properties.
*/
file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create opaque datatype and set the tag to something appropriate.
* For this example we will write and view the data as a character
* array.
*/
dtype = H5Tcreate(H5T_OPAQUE, LEN);
status = H5Tset_tag(dtype, "Character array");
/*
* Create dataspace. Setting maximum size to NULL sets the maximum
* size to be the current size.
*/
space = H5Screate_simple(1, dims, NULL);
/*
* Create the dataset and write the opaque data to it.
*/
dset = H5Dcreate(file, DATASET, dtype, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
status = H5Dwrite(dset, dtype, H5S_ALL, H5S_ALL, H5P_DEFAULT, wdata);
/*
* Close and release resources.
*/
status = H5Dclose(dset);
status = H5Sclose(space);
status = H5Tclose(dtype);
status = H5Fclose(file);
/*
* Now we begin the read section of this example. Here we assume
* the dataset has the same name and rank, but can have any size.
* Therefore we must allocate a new array to read in data using
* malloc().
*/
/*
* Open file and dataset.
*/
file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
dset = H5Dopen(file, DATASET, H5P_DEFAULT);
/*
* Get datatype and properties for the datatype. Note that H5Tget_tag
* allocates space for the string in tag, so we must remember to release it
* later.
*/
dtype = H5Dget_type(dset);
len = H5Tget_size(dtype);
tag = H5Tget_tag(dtype);
/*
* Get dataspace and allocate memory for read buffer.
*/
space = H5Dget_space(dset);
ndims = H5Sget_simple_extent_dims(space, dims, NULL);
rdata = (char *)malloc(dims[0] * len);
/*
* Read the data.
*/
status = H5Dread(dset, dtype, H5S_ALL, H5S_ALL, H5P_DEFAULT, rdata);
/*
* Output the data to the screen.
*/
printf("Datatype tag for %s is: \"%s\"\n", DATASET, tag);
for (i = 0; i < dims[0]; i++) {
printf("%s[%u]: ", DATASET, i);
for (j = 0; j < len; j++)
printf("%c", rdata[j + i * len]);
printf("\n");
}
/*
* Close and release resources.
*/
free(rdata);
#if H5_VERSION_GE(1, 10, 0) && !defined(H5_USE_18_API) && !defined(H5_USE_16_API)
H5free_memory(tag);
#else
free(tag);
#endif
status = H5Dclose(dset);
status = H5Sclose(space);
status = H5Tclose(dtype);
status = H5Fclose(file);
return 0;
}
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