Johan, the only valid way to compare the underlying types of two datatype handles (identifiers) is H5Tequal (or H5T.equal in HDF.PInvoke)
https://support.hdfgroup.org/HDF5/doc/RM/RM_H5T.html#Datatype-Equal Most likely, you will narrow down the type by first establishing the datatype’s “class” via H5Tget_class (H5T.get_class), and then refine your test from there. The HDF5 API handles, including datatype IDs, are opaque and transient, and don’t mean anything as integer values. G. From: Hdf-forum [mailto:[email protected]] On Behalf Of Johan Lindberg Sent: Monday, May 22, 2017 4:23 AM To: [email protected] Subject: [Hdf-forum] Getting native type of HDF5 attribute Hi, I am using Visual Studio (C#) and HDF5 P/Invoke. I have made an HDF5 file with groups and datasets with attributes of different datatypes (in this case, let's say it is an integer, saved as H5T.NATIVE_INT32, but I have the same problem for other datatypes). Now I am making a code to read data from the HDF5 file. To read the attribute value, I first need to determine the data type of the attribute value. I have tried the following: attributeId = H5A.open(groupId, attributeName, H5P.DEFAULT); hid_t attributeSpace = H5A.get_space(attributeId); H5S.class_t extentType = H5S.get_simple_extent_type(attributeSpace); hid_t typeId = H5A.get_type(attributeId); attributeClass = H5T.get_class(typeId); type = H5T.get_native_type(typeId, H5T.direction_t.DEFAULT); H5T.close(typeId); However, the resulting variable type does not match with the H5T.NATIVE_INTEGER type, or any other H5T type I can think of. In fact, even H5T.get_native_type(H5T.NATIVE_INT, H5T.direction_t.DEFAULT) == H5T.NATIVE_INT returns false, so it appears as if H5T.get_native_type() does not return a type, but perhaps a copy or a pointer of it, which is not identical to the type itself. Is this expected behaviour or a bug? How do I correctly figure out the type of an attribute value? Best regards, Johan Lindberg
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