import sys a = [1,2,3] print(hex(id(a))) '''# a is passing into a function, so a counter become 2, can't use normal python to check ''' print(sys.getrefcount(a)) ''' # python internal get refer count but a is double count, due to passing the argumenet into a function write a function with c code, we pass the address of the variable instead of variable name ''' import ctypes def ref_count(address: int): return ctypes.c_long.from_address(address).value print(ref_count(id(a))) b = a print(hex(id(b))) print(ref_count(id(a))) # id(a) is done then pass into ref_count # b = None print(id(b)) '''keep the id of a and see what happen after a is pointing to other value ''' a_id = id(a) a = None print(ref_count(a_id)) # check the address c = 10 d=11 print(ref_count(a_id))