# Reading transformed data from virtual file hdf5

**URL:** <https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070>\
**Category:** C++ Users' Group\
**Created:** [March 11, 2024, 6:47pm UTC](https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070 "2024-03-11T18:47:32Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![anri1085](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/a/aca169/32.png) [@anri1085](https://forum.hdfgroup.org/u/anri1085)\
**Post date:** [March 11, 2024, 6:47pm UTC](https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070/1 "2024-03-11T18:47:32Z")

</div>

I need to create a virutalized hdf5 file using api c/c++ and get its contents in binary format.

There is a code where I write an array to hdf5 dataset:

```auto
    std::vector<int> vec = {7, 1 -2, 0, 8, 6}; // array to write to dataset

    H5FD_CORE;

    //create a virtual file in memory:
    hid_t faplist_id = H5Pcreate(H5P_FILE_ACCESS);
    H5Pset_fapl_core(faplist_id, 1, false);
    hid_t file_id = H5Fopen("data.h5", H5F_ACC_CREAT | H5F_ACC_RDWR, faplist_id);

    //using api c++ create a group and dataset with data
    H5::H5File file(file_id);
    H5::Group group = file.createGroup("/Data");

    hsize_t dims[1];
    dims[0] = vec.size();

    H5::DataSpace dataspace(1, dims);

    H5::DataSet dataset = file.createDataSet("/Data/IntArray", H5::PredType::NATIVE_INT, dataspace);
    dataset.write(vec.data(), H5::PredType::NATIVE_INT);

    // here it is necessary to output a set of bytes contained in the file data.h5 into a standard stream

    file.close();

```

Is there any way to get a binary representation of the transformed HDF5 data?

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<div class="post-metadata">

**Author:** ![bmribler](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/b/a6a055/32.png) [@bmribler](https://forum.hdfgroup.org/u/bmribler)\
**Post date:** [March 12, 2024, 7:26pm UTC](https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070/2 "2024-03-12T19:26:21Z")

</div>

Do you want to output just the dataset or do you want the file image?

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<div class="post-metadata">

**Author:** ![anri1085](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/a/aca169/32.png) [@anri1085](https://forum.hdfgroup.org/u/anri1085)\
**Post date:** [March 16, 2024, 10:02am UTC](https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070/3 "2024-03-16T10:02:15Z")

</div>

i want to output the file image

---

<div class="post-metadata">

**Author:** ![bmribler](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/b/a6a055/32.png) [@bmribler](https://forum.hdfgroup.org/u/bmribler)\
**Post date:** [March 18, 2024, 2:38pm UTC](https://forum.hdfgroup.org/t/reading-transformed-data-from-virtual-file-hdf5/12070/4 "2024-03-18T14:38:37Z")

</div>

Please take a look at these documents:

> **[HDF5FileImageOperations.pdf](https://docs.hdfgroup.org/hdf5/rfc/HDF5FileImageOperations.pdf)**
>
> 1276.50 KB

[https://docs.hdfgroup.org/hdf5/develop/group\_\_\_h5\_i\_m.html](https://docs.hdfgroup.org/hdf5/develop/group___h5_i_m.html)