My Project 1.10.8
compound.cpp
This example shows how to create a compound datatype, write an array which has the compound datatype to the file, and read back fields' subsets.
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://www.hdfgroup.org/licenses. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example shows how to create a compound datatype,
* write an array which has the compound datatype to the file,
* and read back fields' subsets.
*/
#include <iostream>
using std::cout;
using std::endl;
#include <string>
#include "H5Cpp.h"
using namespace H5;
const H5std_string FILE_NAME("SDScompound.h5");
const H5std_string DATASET_NAME("ArrayOfStructures");
const H5std_string MEMBER1("a_name");
const H5std_string MEMBER2("b_name");
const H5std_string MEMBER3("c_name");
const int LENGTH = 10;
const int RANK = 1;
int
main(void)
{
/* First structure and dataset*/
typedef struct s1_t {
int a;
float b;
double c;
} s1_t;
/* Second structure (subset of s1_t) and dataset*/
typedef struct s2_t {
double c;
int a;
} s2_t;
// Try block to detect exceptions raised by any of the calls inside it
try {
/*
* Initialize the data
*/
int i;
s1_t s1[LENGTH];
for (i = 0; i < LENGTH; i++) {
s1[i].a = i;
s1[i].b = i * i;
s1[i].c = 1. / (i + 1);
}
/*
* Turn off the auto-printing when failure occurs so that we can
* handle the errors appropriately
*/
Exception::dontPrint();
/*
* Create the data space.
*/
hsize_t dim[] = {LENGTH}; /* Dataspace dimensions */
DataSpace space(RANK, dim);
/*
* Create the file.
*/
H5File *file = new H5File(FILE_NAME, H5F_ACC_TRUNC);
/*
* Create the memory datatype.
*/
CompType mtype1(sizeof(s1_t));
mtype1.insertMember(MEMBER1, HOFFSET(s1_t, a), PredType::NATIVE_INT);
mtype1.insertMember(MEMBER3, HOFFSET(s1_t, c), PredType::NATIVE_DOUBLE);
mtype1.insertMember(MEMBER2, HOFFSET(s1_t, b), PredType::NATIVE_FLOAT);
/*
* Create the dataset.
*/
DataSet *dataset;
dataset = new DataSet(file->createDataSet(DATASET_NAME, mtype1, space));
/*
* Write data to the dataset;
*/
dataset->write(s1, mtype1);
/*
* Release resources
*/
delete dataset;
delete file;
/*
* Open the file and the dataset.
*/
file = new H5File(FILE_NAME, H5F_ACC_RDONLY);
dataset = new DataSet(file->openDataSet(DATASET_NAME));
/*
* Create a datatype for s2
*/
CompType mtype2(sizeof(s2_t));
mtype2.insertMember(MEMBER3, HOFFSET(s2_t, c), PredType::NATIVE_DOUBLE);
mtype2.insertMember(MEMBER1, HOFFSET(s2_t, a), PredType::NATIVE_INT);
/*
* Read two fields c and a from s1 dataset. Fields in the file
* are found by their names "c_name" and "a_name".
*/
s2_t s2[LENGTH];
dataset->read(s2, mtype2);
/*
* Display the fields
*/
cout << endl << "Field c : " << endl;
for (i = 0; i < LENGTH; i++)
cout << s2[i].c << " ";
cout << endl;
cout << endl << "Field a : " << endl;
for (i = 0; i < LENGTH; i++)
cout << s2[i].a << " ";
cout << endl;
/*
* Create a datatype for s3.
*/
CompType mtype3(sizeof(float));
mtype3.insertMember(MEMBER2, 0, PredType::NATIVE_FLOAT);
/*
* Read field b from s1 dataset. Field in the file is found by its name.
*/
float s3[LENGTH]; // Third "structure" - used to read float field of s1
dataset->read(s3, mtype3);
/*
* Display the field
*/
cout << endl << "Field b : " << endl;
for (i = 0; i < LENGTH; i++)
cout << s3[i] << " ";
cout << endl;
/*
* Release resources
*/
delete dataset;
delete file;
} // end of try block
// catch failure caused by the H5File operations
catch (FileIException error) {
error.printErrorStack();
return -1;
}
// catch failure caused by the DataSet operations
catch (DataSetIException error) {
error.printErrorStack();
return -1;
}
// catch failure caused by the DataSpace operations
catch (DataSpaceIException error) {
error.printErrorStack();
return -1;
}
// catch failure caused by the DataSpace operations
catch (DataTypeIException error) {
error.printErrorStack();
return -1;
}
return 0;
}
CompType is a derivative of a DataType and operates on HDF5 compound datatypes.
Definition: H5CompType.h:25
Class DataSet operates on HDF5 datasets.
Definition: H5DataSet.h:28
void write(const void *buf, const DataType &mem_type, const DataSpace &mem_space=DataSpace::ALL, const DataSpace &file_space=DataSpace::ALL, const DSetMemXferPropList &xfer_plist=DSetMemXferPropList::DEFAULT) const
Writes raw data from an application buffer to a dataset.
Definition: H5DataSet.cpp:492
void read(void *buf, const DataType &mem_type, const DataSpace &mem_space=DataSpace::ALL, const DataSpace &file_space=DataSpace::ALL, const DSetMemXferPropList &xfer_plist=DSetMemXferPropList::DEFAULT) const
Reads raw data from the specified dataset.
Definition: H5DataSet.cpp:417
Definition: H5Exception.h:131
Class DataSpace inherits from IdComponent and provides wrappers for the HDF5's dataspaces.
Definition: H5DataSpace.h:25
Definition: H5Exception.h:103
Definition: H5Exception.h:110
static void printErrorStack(FILE *stream=stderr, hid_t err_stack=H5E_DEFAULT)
Prints the error stack in a default manner.
Definition: H5Exception.cpp:315
Definition: H5Exception.h:89
Class H5File represents an HDF5 file and inherits from class Group as file is a root group.
Definition: H5File.h:25
DataSet openDataSet(const char *name, const DSetAccPropList &dapl=DSetAccPropList::DEFAULT) const
Opens an existing dataset at this location.
Definition: H5Location.cpp:1006
DataSet createDataSet(const char *name, const DataType &data_type, const DataSpace &data_space, const DSetCreatPropList &create_plist=DSetCreatPropList::DEFAULT, const DSetAccPropList &dapl=DSetAccPropList::DEFAULT, const LinkCreatPropList &lcpl=LinkCreatPropList::DEFAULT) const
Creates a new dataset at this location.
Definition: H5Location.cpp:950
Definition: H5AbstractDs.cpp:34


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