The problematic line is:
hsize_t compound_dtype_size = sizeof(compound_dtype);
The documentation states:
[in] type_size The size in bytes of the structure associated with the table; This value is obtained with
sizeof().
Notice that it says “… the structure associated with the table,” which you said you don’t have.
Clearly, sizeof(compound_dtype) == sizeof(hsize_t) == 8 < 28, which is the problem.
sizeof() can work only with a predefined struct. The documentation should be clearer on this.
What would work is hsize_t compound_dtype_size = H5Tget_size(compound_dtype);
OK?
G.