String attribute with HDF5 Lite

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1

Hello,

I know how to manipulate attribute with the standard HDF5 API and now I am
learning the Lite API to reduce the lines of code in my projects.

I write the result of H5LTdtype_to_text to an already existing dataset with
the function H5LTset_attribute_string, this works as intended. When I try
to read the string using H5LTget_attribute_string I can't find a way to
know the string length for the buffer allocation.
If I use H5LTget_attribute_info(file_id, "/dset", "attr", &str_size,
&type_class, &byte_size) the function do not fail but the variable str_size
is left untouched.

What is the correct way to get the string size?

Thanks,
Mario

2

If you are reading a variable length string with H5LTget_attribute_string (H5T_VARIABLE) then you don’t need to allocate the string, just pass in a pointer and the library will handle the allocations. If you are reading a fixed length string then you need to allocate a string that is “large enough”. Due to an oversight on our part you can not find the length of the string using the high-level routines, you will need to use the low-level routines to find the length.

Scot

···

On Jun 23, 2015, at 8:12 AM, Mario Pezzoni <pezzoni.mario@gmail.com> wrote:

Hello,

I know how to manipulate attribute with the standard HDF5 API and now I am learning the Lite API to reduce the lines of code in my projects.

I write the result of H5LTdtype_to_text to an already existing dataset with the function H5LTset_attribute_string, this works as intended. When I try to read the string using H5LTget_attribute_string I can't find a way to know the string length for the buffer allocation.
If I use H5LTget_attribute_info(file_id, "/dset", "attr", &str_size, &type_class, &byte_size) the function do not fail but the variable str_size is left untouched.

What is the correct way to get the string size?

Thanks,
Mario
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