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/************************************************************
This example shows how to read and write compound
datatypes to an attribute. The program first writes
compound structures to an attribute 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_cmpdatt.h5"
#define DATASET "DS1"
#define ATTRIBUTE "A1"
#define DIM0 4
typedef struct {
int serial_no;
char *location;
double temperature;
double pressure;
} sensor_t; /* Compound type */
int
main(void)
{
hid_t file, filetype, memtype, strtype, space, dset, attr;
/* Handles */
herr_t status;
hsize_t dims[1] = {DIM0};
sensor_t wdata[DIM0], /* Write buffer */
*rdata; /* Read buffer */
int ndims;
hsize_t i;
/*
* Initialize data.
*/
wdata[0].serial_no = 1153;
wdata[0].location = "Exterior (static)";
wdata[0].temperature = 53.23;
wdata[0].pressure = 24.57;
wdata[1].serial_no = 1184;
wdata[1].location = "Intake";
wdata[1].temperature = 55.12;
wdata[1].pressure = 22.95;
wdata[2].serial_no = 1027;
wdata[2].location = "Intake manifold";
wdata[2].temperature = 103.55;
wdata[2].pressure = 31.23;
wdata[3].serial_no = 1313;
wdata[3].location = "Exhaust manifold";
wdata[3].temperature = 1252.89;
wdata[3].pressure = 84.11;
/*
* Create a new file using the default properties.
*/
file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
/*
* Create variable-length string datatype.
*/
strtype = H5Tcopy(H5T_C_S1);
status = H5Tset_size(strtype, H5T_VARIABLE);
/*
* Create the compound datatype for memory.
*/
memtype = H5Tcreate(H5T_COMPOUND, sizeof(sensor_t));
status = H5Tinsert(memtype, "Serial number", HOFFSET(sensor_t, serial_no), H5T_NATIVE_INT);
status = H5Tinsert(memtype, "Location", HOFFSET(sensor_t, location), strtype);
status = H5Tinsert(memtype, "Temperature (F)", HOFFSET(sensor_t, temperature), H5T_NATIVE_DOUBLE);
status = H5Tinsert(memtype, "Pressure (inHg)", HOFFSET(sensor_t, pressure), H5T_NATIVE_DOUBLE);
/*
* Create the compound datatype for the file. Because the standard
* types we are using for the file may have different sizes than
* the corresponding native types, we must manually calculate the
* offset of each member.
*/
filetype = H5Tcreate(H5T_COMPOUND, 8 + sizeof(hvl_t) + 8 + 8);
status = H5Tinsert(filetype, "Serial number", 0, H5T_STD_I64BE);
status = H5Tinsert(filetype, "Location", 8, strtype);
status = H5Tinsert(filetype, "Temperature (F)", 8 + sizeof(hvl_t), H5T_IEEE_F64BE);
status = H5Tinsert(filetype, "Pressure (inHg)", 8 + sizeof(hvl_t) + 8, H5T_IEEE_F64BE);
/*
* Create dataset with a null dataspace.
*/
space = H5Screate(H5S_NULL);
dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
status = H5Sclose(space);
/*
* Create dataspace. Setting maximum size to NULL sets the maximum
* size to be the current size.
*/
space = H5Screate_simple(1, dims, NULL);
/*
* Create the attribute and write the compound data to it.
*/
attr = H5Acreate(dset, ATTRIBUTE, filetype, space, H5P_DEFAULT, H5P_DEFAULT);
status = H5Awrite(attr, memtype, wdata);
/*
* Close and release resources.
*/
status = H5Aclose(attr);
status = H5Dclose(dset);
status = H5Sclose(space);
status = H5Tclose(filetype);
status = H5Fclose(file);
/*
* Now we begin the read section of this example. Here we assume
* the attribute has the same name and rank, but can have any size.
* Therefore we must allocate a new array to read in data using
* malloc(). For simplicity, we do not rebuild memtype.
*/
/*
* Open file, dataset, and attribute.
*/
file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
dset = H5Dopen(file, DATASET, H5P_DEFAULT);
attr = H5Aopen(dset, ATTRIBUTE, H5P_DEFAULT);
/*
* Get dataspace and allocate memory for read buffer.
*/
space = H5Aget_space(attr);
ndims = H5Sget_simple_extent_dims(space, dims, NULL);
rdata = (sensor_t *)malloc(dims[0] * sizeof(sensor_t));
/*
* Read the data.
*/
status = H5Aread(attr, memtype, rdata);
/*
* Output the data to the screen.
*/
for (i = 0; i < dims[0]; i++) {
printf("%s[%llu]:\n", ATTRIBUTE, i);
printf("Serial number : %d\n", rdata[i].serial_no);
printf("Location : %s\n", rdata[i].location);
printf("Temperature (F) : %f\n", rdata[i].temperature);
printf("Pressure (inHg) : %f\n\n", rdata[i].pressure);
}
/*
* Close and release resources. H5Dvlen_reclaim will automatically
* traverse the structure and free any vlen data (strings in this
* case).
*/
status = H5Dvlen_reclaim(memtype, space, H5P_DEFAULT, rdata);
free(rdata);
status = H5Aclose(attr);
status = H5Dclose(dset);
status = H5Sclose(space);
status = H5Tclose(memtype);
status = H5Tclose(strtype);
status = H5Fclose(file);
return 0;
}
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