I have a problem with python and c++ data type conversion

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I try to create an ndarray(whose size is 5, and dtype is float) in c++ interface as the return value, which will be passed to a python function as output.
I tried this ↓

and this ↓

But all the methods turns out that the python function output data only retains one digit after the decimal point，
which does not match the precision of float.
For example:
the return_data[0]=0.0025783
but the arr[0]=0.0

May I ask where did I make a mistake?
Anyone gets any ideas??